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TRANSCRIPT
PASSIVE COOLING STRATEGIES FOR BUILDINGS IN UTAH
by
Alexis Suggs
A Senior Honors Thesis Submitted to the Faculty of The University of Utah
In Partial Fulfillment of the Requirements for the
Honors Degree in Bachelor of Science
In
Architectural Studies
Approved: ______________________________ Jörg Rügemer Thesis Faculty Supervisor
_____________________________ Mira Locher Chair, Department of Architecture
_______________________________ Mira Locher Honors Faculty Advisor
_____________________________ Sylvia D. Torti, PhD Dean, Honors College
May 2016 Copyright © 2016
All Rights Reserved
ii
ABSTRACT
This thesis explores techniques and strategies that can be used to passively cool buildings
in Utah. The first portion contains a brief explanation of what passive cooling is, why
Utah was chosen as the focus, a short history of air conditioning, and why passive
cooling is important. The second part of this thesis goes into more depth by presenting
and analyzing three case studies. The first case study is the Zion Canyon Visitor Center in
Springdale, Utah and is a great example of a whole system approach to passive cooling.
The second case study is the NREL RSF (National Renewable Energy Laboratory
Research Support Facility) in Golden, Colorado which demonstrates a multitude of
techniques regarding the rejection of heat and the treatment of windows in relation to
passive cooling. The third case study is the Boroujerdi House in Kashan, Iran which
demonstrates how buildings were designed to combat heat prior to modern day air
conditioning, as well as showing how the layout of a building can contribute to passive
cooling. Following this section is a presentation of a hypothetical winery. This winery
takes the techniques that were presented in the case studies, selects the ones that are the
most relevant to the site in Park City, Utah, and brings them together to form a building
that can be used as a reference for designing a passively cooled building in the Salt Lake
Valley. The final part of this thesis seeks to reiterate the importance of passive cooling
for buildings in Utah and why architects should care. Ultimately, the goal of this thesis is
that architects, builders, those seeking to commission a building, those purchasing a
building, and the general public as a whole, would see the value in passive cooling and
turn away from a mindset of endless consumption and toward a mindset of sustainability.
iii
TABLE OF CONTENTS
ABSTRACT ii
INTRODUCTION 1
UTAH 2
PASSIVE COOLING 5
AIR CONDITIONING 5
WHY PASSIVE COOLING MATTERS 7
Environmental Stewardship 7
Cost and the Power Grid 9
HOW TO IMPLEMENT PASSIVE COOLING 15
CASE STUDIES 17
ZION CANYON VISITOR CENTER 19
Passive Systems 22
Building Orientation and Window Placement 22
Window Overhangs 27
Natural Ventilation 29
Night Flushing 30
Cold Roof Design 31
Thermal Massing 32
Building Massing 32
Evaporative Cooling Towers 34
Effectiveness 36
iv
Implications 38
Conclusion 39
NREL RSF 41
Passive Systems 42
Orientation and Windows 42
Natural Ventilation 45
Night Flushing 47
Effectiveness 47
Implications 49
BOROUJERDI HOUSE 52
Passive Systems 55
Orientation, Window, and Seasonal Living 55
Thermal Mass 59
Courtyard 61
Wind Towers and Natural Ventilation 62
Implications 65
SALT LAKE VALLEY 68
PARK CITY WINERY 70
Passive Systems 71
Thermal Mass 71
Orientation and Windows 76
Vegetation 78
Natural Ventilation 79
v
Performance 80
Implications 82
CONCLUSION 83
Architects 83
Tools for Passive Cooling 84
Passive Cooling for Utah 85
ACKNOWLEDGMENTS 87
REFERENCES 88
CANDIDATE INFORMATION 94
INTRODUCTION
Designing and constructing buildings that can cool themselves entirely, or almost
entirely, through passive means is a very real possibility, and one that needs to be
considered more frequently in Utah. Many architects think that it is their job is to just
design the building, and that the means through which the building is heated and cooled
are for an engineer to figure out. In that type of scenario the architect is giving up a lot of
the design responsibilities to someone else, and is missing out on the opportunity to do so
much more for the building and for the building’s occupants, as well as for the
environment. There is potential to gain financially, aesthetically, and environmentally, as
well as having the potential to gain in other indirect ways such as lowering the
summertime strain on the grid and setting a positive example for developing countries.
This thesis aims to show why passive cooling is important for Utah, as well as for
any climate that has cooling needs. It explains a variety of methods and how passive
cooling can be achieved. An explanation of passive cooling is given, followed by general
methods of implementation. Subsequently, a brief history of air conditioning and passive
cooling is given to provide the reader with the necessary context. Following that is a
discussion of why passive cooling matters in terms of the environment, global warming,
finances, and several other factors. Thereafter, three different passively cooled buildings
are analyzed as case studies. This is to show how passive cooling has been implemented
in a variety of different types of buildings, as well as in different locations with climates
similar to Utah. After the case studies have been analyzed, the main ideas and techniques
used in them are extracted and are applied to a hypothetical building in Utah. This
hypothetical building is a winery and serves as an example of how the various passive
cooling techniques can come together for a building in Utah’s specific climate zone.
Ultimately, the goal of this thesis is that at the end the reader will want to incorporate
passive design into their future buildings, be it in designing a building, purchasing a
building, or commissioning the design of a building.
UTAH
The way in which passive cooling is implemented in a building depends a lot on
where the building is located as not every technique will work in every climate. Hot and
dry climates can benefit from the addition of humidity to the air because it can cool the
air through evaporation. In hot and humid climates however adding more humidity to the
air will make the conditions worse and will not cool the building. Because passive
cooling is very site specific the focal point of this thesis is Utah, and in particular Salt
Lake City and the surrounding valley. Utah was chosen as the focus location and climate
of this thesis so that the discussion and techniques presented aren’t universal, but rather
are specific and can be applicable. Many of the techniques shown will be labeled as Utah
specific, climate specific, and general because the information presented here can also be
applied to other locations.
Additionally, Utah was chosen as the focus location because of the high cooling
loads that its buildings have in the summer. The climate of Salt Lake City, Utah, in the
warm months of the year, is hot and dry with a lot of sunshine. From 1948 to 2012 it had
an average of 1083.87 cooling degree days (using 65°F as the base) with an average
standard deviation of 201.79 cooling degree days (CDD).1 This means that there is
potential for some years to have upwards of 1285 CDD, but the last five years have been
reaching above this average with 2011 having 1135 CDD, 2012 having 1548 CDD, 2013
having 1769 CDD, 2014 having 1242 CDD, and 2015 having 1444 CDD.2 Norbert
Lechner in his book “Heating, Cooling, Lighting: Sustainable Design Methods For
Architects” states that “Areas with more than 1500 CDD per year are characterized by
long, hot summers and substantial cooling requirements.”3 While Salt Lake City’s
averages from 1948-2012 put it below this 1500+ CDD category, the last few years have
been substantially warmer. This rise in CDD along with global warming indicates that the
rise of Salt Lake City’s CDD is apt to be continuously high, thus putting Salt Lake City in
the general region of the 1500 CDD category. The large amount of CDD is a direct result
of Utah having approximately six months of the year where the average high is at or
above 65°F. These months are May through October with the average high in May being
71°F, June being 82°F, July being 90°F, August being 89°F, September being 78°F, and
October being 65°F4.
On top of the high temperatures, Utah buildings are exposed to large amounts of
sunlight that can cause high heat gains to buildings. For example, Salt Lake City gets an
average of 3059 annual hours of sun5, making it one of the sunniest cities in the United
States. For comparison San Francisco, California gets an average of 2950 hours of sun
1 "SALT LAKE CITY INTL AP, UTAH: Monthly Total Cooling Degree Days," table, WRCC, April 4, 2013, accessed January 1, 2016, http://www.wrcc.dri.edu/cgi-bin/cliMONtcdd.pl?ut7598. 2 "Monthly Degree Day Comparison (Station: UT08)," table, Weather Data Depot, 2015, accessed January 1, 2016, http://www.weatherdatadepot.com/. 3 Norbert Lechner, Heating, Cooling, Lighting: Sustainable Design For Architects, 4th ed. (Hoboken, NJ: Wiley, 2014), 92. 4 "Climate Utah - Salt Lake City," US Climate Data, last modified 2015, accessed December 31, 2015, http://www.usclimatedata.com/climate/utah/united-states/3214-SLC. 5 Ibid
per year6, Honolulu, Hawaii get 3041 hours of sun per year,7 and Detroit, Michigan gets
2375 hours per year8. These 3059 hours of sun per year equal out to 8.38 hours of sun per
day if evenly distributed. This means that there are very few days in Salt Lake City when
the sun is not shinning and in which a building is not going to have some level of sun
exposure to account for.
In addition to the heat and near constant sun, Salt Lake City is also very dry, as it
only receives 18.58 inches of rain per year. On average these 18.58 inches are distributed
over 88 days each year, with only 34 of them being during the six warm months.9 In
comparison San Francisco gets on average 23.64 inches of rain per year spread over 68
days,10 Honolulu gets 17.13 inches over 154 days,11 and Detroit gets 30.97 inches over
133 days.12 Given these numbers Salt Lake City isn’t the driest of American cities, but it
certainly doesn’t get a lot of rain over the course of the year. These three factors
combined; a high number of CDD and annual hours of sun, along with a low amount of
precipitation make Salt Lake City a prime location for passive cooling to be used.
6 "San Francisco Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/san-francisco/california/united-states/usca0987. 7 "Honolulu Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/honolulu/hawaii/united-states/ushi0026. 8 "Detroit Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/detroit/michigan/united-states/usmi0229. 9 "Climate Utah - Salt Lake City," US Climate Data, last modified 2015, accessed December 31, 2015, http://www.usclimatedata.com/climate/utah/united-states/3214-SLC. 10 "San Francisco Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/san-francisco/california/united-states/usca0987. 11 "Honolulu Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/honolulu/hawaii/united-states/ushi0026. 12 "Detroit Weather Averages," table, US Climate Data, 2015, accessed January 1, 2016, http://www.usclimatedata.com/climate/detroit/michigan/united-states/usmi0229.
PASSIVE COOLING
Passive cooling is a term used to encompass the wide range of design techniques
that can be employed in a building to cool it without the use of mechanical systems.
Some of these systems function on their own after they are installed and do not need any
further input from the occupants of the building other than the occasional maintenance.
Other passive systems do need occupant interaction, such as the opening and closing of a
window. Passive systems do not need to be completely free of mechanical systems, so
long as the systems used are minimal; using a computer system and a small motor to open
and close windows during the day would be considered passive. This is because the
window is cooling the building on its own for the majority of the time, it just needs the
help of the motor to open and close when needed. It is also considered passive because of
the small amount of energy used in the operation of the motor. When compared to the
operational costs and the energy consumed in a traditional air conditioning system, the
few watts that it takes a motor to open a window is so minimal that it barely registers, and
thus it can be considered passive in the long run.
AIR CONDITIONING
While it may feel like passive cooling is a new strategy, it is not. People have
known how to design passively cooled buildings for thousands of years out of necessity.
It is only within the last one hundred years that design and building professionals seem to
have forgotten how to use passive design strategies because of the invention of air
conditioning. Air conditioning was invented in 1902 when Willis Carrier designed the
first modern cooling unit. However, it wasn’t until 1904 that the public first experienced
comfort cooling as it was called back then, and it wasn’t until 1929 that room cooling
systems hit the market. By 1947 low-cost air conditioners were widely available and
people started installing them in their homes at a higher rate.13 What also happened at this
time that made the building industry temporarily forget about passive cooling was the rise
of the international style. The rise of international style began in the 1920s and went into
the 1970s14, coinciding with the rise of air conditioning. Air conditioning allowed
architects that practiced international style to create buildings that can exist anywhere and
which don’t reference the surrounding climate, culture, or location; they have the ability
to be transplanted anywhere. Among other things, international style buildings tended to
use a lot of glass, steel, and concrete in their construction. While this isn’t necessarily a
bad thing, the way in which glass, steel, and concrete were used was negative in terms of
passive systems versus mechanical systems. With the large expanses of glass and an
emphasis on buildings that are placeless, or international, the resulting buildings tended
to rely heavily on mechanical systems to heat and cool them. As a whole, international
style brought this mentality that architects could design whatever they want and not have
to take into account the heating and cooling of the building because mechanical systems
would take care of it. They could design a glass box, which is very impractical from an
energy standpoint due to the massive amounts of heat lost in the winter and the massive
amounts of heat gained in the summer. They could design these types of buildings
because mechanical systems would take care of it, and prior to the energy crisis of the
13 Paul Lester, "History of Air Conditioning," US Department of Energy, last modified July 20, 2015, accessed January 2, 2016, http://energy.gov/articles/history-air-conditioning. 14 "International Style," in Britannica (2014), last modified August 8, 2014, accessed January 2, 2016, http://www.britannica.com/art/International-Style-architecture.
1970s, the amount of energy used wasn’t a concern. This type of thinking continued even
through the energy crisis and continues on today. The main difference though is that now
people are more concerned with energy. However, the new approach to energy
conservation tends to be through more efficient mechanical systems, rather than trying to
use passive systems incorporated in the building’s design, as a method for reducing
energy consumption. This is the reason that people have temporarily forgotten about
passive heating and cooling. However, air conditioning and international style type
thinking is only 100 years old, while passive cooling is thousands of years old. If
architects and builders open their eyes and realize that passive cooling is relevant and
important, then the techniques and methods needed to design with passive cooling in
mind are not that far back in history and can be easily reincorporated into buildings in the
future.
WHY PASSIVE COOLING MATTERS
Environmental Stewardship
Passive cooling is not only a way to cool buildings; it is also a way of being
environmentally conscience. Global warming is a very real thing that needs to be
addressed in a serious manner if major consequences are to be avoided, or at least curbed.
In order to address global warming and the environment as a whole many people have
chosen to target industry and transportation. While these are areas that certainly have a
large impact on the environment, with transportation accounting for 27 percent of all the
energy consumed in the United States each year and industry accounting for 25 percent,
neither of them come close individually to the impact that buildings have on the
environment because buildings alone are accountable for up to 48 percent of all the
energy consumed in the United States each year.15 If there is any one area to work on to
best reduce the United States’ energy consumption it is buildings more than industry or
transportation.
The energy used by buildings in the United States is so large that it is measured in
quadrillions of Btu. The energy use by the residential sector in 2009 was 10.18
quadrillion Btu16 and the energy use by the commercial sector in 2014 was 29.82
quadrillion Btu, totaling 40 quadrillion Btu annually.17 The use of such a large amount of
energy has negative effects on the environment because the large majority of that energy
comes from non-renewable energy sources such as fossil fuels. With modern technology
and passive techniques this 40 quadrillion Btu of energy can be reduced significantly.
If the energy use of buildings can be reduced then not only will the environment
benefit, but the United States would be setting a better example for developing countries.
Because the United States is a world leader many developing countries look to it as an
example of how to shape their own countries. Countries, like China, see the United States
consuming energy at an endless and unrestricted manner and think that they can too. The
earth can only support so much depletion of its resources before it reaches a tipping point
and more permanent damage is done. This would lower the quality of life for future
15 Norbert Lechner, Heating, Cooling, Lighting: Sustainable Design For Architects, 4th ed. (Hoboken, NJ: Wiley, 2014), 2. 16 "Heating and cooling no longer majority of U.S. home energy use," US Energy Information Administration, last modified March 7, 2013, accessed January 4, 2016, http://www.eia.gov/todayinenergy/detail.cfm?id=10271&src=%E2%80%B9%20Consumption%20%20%20%20%20%20Residential%20Energy%20Consumption%20Survey%20(RECS)-f1. 17 "How much energy is consumed in residential and commercial buildings in the United States?," United States Energy Information Administration, last modified April 3, 2015, accessed January 7, 2016, http://www.eia.gov/tools/faqs/faq.cfm?id=86&t=1.
generations. If more countries consume energy like the United States does then the
tipping point will be reached much sooner and far more damage will be done. Instead,
what the United States needs to do is set a good example by using passive cooling to
lower overall energy needs, and then use high efficiency mechanical systems to take care
of what is left. If that is done then other countries will follow suit and more energy
outside of the United States will be saved.
Cost and the Power Grid
Not only should passive cooling be considered for environmental reasons, it
should also be considered for financial reasons. In the United States the cost of residential
electricity ranges from 8.64 cents per kWh to 36.90 cents per kWh. In Utah the cost of
residential electricity is 10.71 cents per kWh,18 commercial is 8.01-9.0 cents per kWh,19
and industrial is less than 6.0 cents per kWh.20 These prices are low in comparison to the
rest of the United States, especially states such as New York where residential prices are
19.96 cents per kWh.21 However, the cost of energy in the summer increases in Utah due
to the high number of people running their air conditioners and creating a high demand.
18 "Total Average Residential Rates Per State," map, United States Energy Information Administration, June 2014, accessed January 7, 2016, https://www.rockymountainpower.net/about/rar/rpc.html. 19 "Total Average Commercial Rates Per State," map, United States Energy Information Administration, June 2014, accessed January 7, 2016, https://www.rockymountainpower.net/about/rar/cpc.html. 20 "Total Average Industrial Rates Per State," map, United States Energy Information Administration, June 2014, accessed January 7, 2016, https://www.rockymountainpower.net/about/rar/ipc.html. 21 "Total Average Residential Rates Per State," map, United States Energy Information Administration, June 2014, accessed January 7, 2016, https://www.rockymountainpower.net/about/rar/rpc.html.
Figure 1: Commercial, Industrial, and Residential Electricity Rates by State Source: Rocky Mountain Power 2014
Rocky Mountain Power is the main provider of electricity to Utah, and in
particular to the Salt Lake City valley. Their summer electricity rates run from May 1st
through September 30th and are based on a tiered pricing structure. If a residence uses up
to 400 kWh each month then they are charged 8.9 cents per kWh. Any additional kWh up
to 999 kWh costs 11.6 cents per kWh, and consuming more than 1,000 kWh in a month
makes the cost go up to 14.5 cents per kWh.22 This can get expensive very quickly
because a typical 6,000 Btu room air conditioner uses 540 kWh per month, a typical
9,000 Btu room air conditioner uses 756 Btu per month, and a typical 2.5 ton central air
22 "Summer Electric Rates," Rocky Mountain Power, accessed January 7, 2016, https://www.rockymountainpower.net/summerrates.
conditioner uses 1,000 kWh of electricity per month.23 By having all of these extra
charges during the peak times Rocky Mountain Power is discouraging people from
running their air conditioning when there is a lot of strain on the grid. If they didn’t
charge these types of rates then they might not be able to provide all of the electricity that
people demanded. In fact, Rocky Mountain Power has said that they are planning for new
power plants to be built to accommodate the increase in electricity demand. This may
seem like a positive action, and it is in terms of providing enough electricity, but it means
that the cost per kWh increases to cover the cost of the new construction.
This seemingly low cost of electricity becomes a lot more of a factor to consider
when applied to the amount of electricity that the United States consumes in a year. In
2009 the total energy consumption of homes was 10.18 quadrillion Btu with the average
US household consuming 11,320 kWh of electricity. This energy was used by space
heating, air conditioning, water heating, appliances, electronics, and lighting of which
41.5 percent was for space heating, 6.2 percent for air conditioning, 17.7 percent for
water heating, and 34.6 percent for appliances, electronics, and lighting.24 The average
residential energy expenditure per person per year in 2012 was $75025, which means that
each person spent $46.50 on air conditioning. In Utah in 2012 it cost each person $518
per year for these residential energy expenditures,26 which means that each person in
Utah spends and average of $32 per year on space cooling. While this may seem low, it
23 "Time of Day FAQ," Rocky Mountain Power, accessed January 7, 2016, https://www.rockymountainpower.net/ya/po/otou/utah/todf.html. 24 "Heating and cooling no longer majority of U.S. home energy use," US Energy Information Administration, last modified March 7, 2013, accessed January 4, 2016, http://www.eia.gov/todayinenergy/detail.cfm?id=10271&src=%E2%80%B9%20Consumption%20%20%20%20%20%20Residential%20Energy%20Consumption%20Survey%20(RECS)-f1. 25 "US Energy Expenditure Per Person," infographic, US Department of Energy, accessed January 4, 2016, http://energy.gov/maps/how-much-do-you-spend-energy. 26 Ibid
means that an average American family of six spends $279 per year on space cooling and
an average Utah family of six spends $192 per year, with the number growing to $11
billion per year when applied to the United States as a whole.27
Figure 2: United States Energy Expenditure per Person Source: EIA State Energy Data System
27 "Energy Saver 101: Everything You Need to Know About Home Cooling," infographic, US Department of Energy, June 13, 2014, accessed January 4, 2016, http://energy.gov/articles/energy-saver-101-infographic-home-cooling.
Figure 3: Utah Energy Expenditure per Person Source: EIA State Energy Data System
Given the high total cost of electricity for the whole nation in order to power
everything from appliances to air conditioning it would be logical for either efficiency to
rise or for use to decrease, or in the best case scenario for both to happen. Efficiency has
increased, but consumption has increased as well which has essentially cancelled out any
benefit that might have been gained by higher efficiency systems. From 1993 to 2009 the
total energy consumption of US homes has gone from 10.01 quadrillion Btu to 10.18
quadrillion Btu. In this time the energy spent on space heating and water heating has
decreased, but the energy spent on air conditioning and appliances, electronics, and
lighting has increased.28 This increase in energy spent on air conditioning comes from the
fact that nearly 90 percent of new homes are now built with central air conditioning.29 It
has become the standard way to cool a building and people now expect it in their homes.
28 "Heating and cooling no longer majority of U.S. home energy use," US Energy Information Administration, last modified March 7, 2013, accessed January 4, 2016, http://www.eia.gov/todayinenergy/detail.cfm?id=10271&src=%E2%80%B9%20Consumption%20%20%20%20%20%20Residential%20Energy%20Consumption%20Survey%20(RECS)-f1. 29 "Residential Energy Consumption Survey (RECS) 2009," EIA, last modified August 19, 2011, accessed January 5, 2016, http://www.eia.gov/consumption/residential/reports/2009/air-conditioning.cfm.
Figure 4: Energy Consumption in Homes by End Use Source: US Energy Information Administration
The cost of electricity doesn’t stay stagnant, nor does it go down. Since 1960, and
even earlier, the price of electricity has been increasing steadily with the price in 1960
being around two cents per kWh whereas in 2009 it was close to ten cents per kWh hour
as a national average.30 This means that beyond the initial savings of having a building
use passive cooling, over time it will add more and more value to the building as
electricity prices continue to climb.
30 Rocky Mountain Power, "Price of Electricity in Relation to Build Cycle," chart, January 2011, JPG.
Figure 5: Growing Electricity Use and Price Source: Rocky Mountain Power 2011
HOW TO IMPLEMENT PASSIVE COOLING
Contrary to popular belief, the best way to reduce the cooling loads and the
electricity needs of a building isn’t to make the mechanical systems more efficient. If the
mechanical systems are the starting point for making a more energy conscience building
then it is like starting at the top of the ladder and missing out on all of the opportunities
below. For passive cooling it is best to use the three tier approach: heat rejection, then
passive cooling strategies, then mechanical equipment. By using this method, which is
borrowed from Norbert Lechner’s book “Heating, Cooling, Lighting: Sustainable Design
Methods for Architects”, the architect can first reduce the overall building’s energy and
cooling needs, then work to make what cooling and energy needs are left efficient. By
using this method Lechner says that the energy consumption of buildings can be reduced
by as much as 80 percent. Although in some cases, such as smaller buildings and ones
very diligently designed, the cooling energy needed for the building can be zero.
The tiered method first starts with heat rejection. Heat rejection is key to passive
cooling because the passive design strategies implemented to lower the interior building
temperature can only go so far. Additionally, heat rejection is important because it means
that there is better occupant comfort near the areas where heat is entering the building
and it means that less passive cooling systems are needed and they don’t have to work
nearly as hard. As a whole, heat rejection is the most important part of passive cooling
because it sets the stage for how well the rest of the building can combat the heat that
does enter the building, and it also largely determines if mechanical systems will be
needed after the passive systems have done their job.
The second tier is the use of passive cooling systems. These systems are in charge
of taking care of the heat that has been able to enter the building, or the heat which has
been generated within the building. Among other things, these systems can dispel the
heat, add moisture where appropriate, move air when necessary, and bring in cool air to
the interior. This tier is important because as successful as heat rejection may be some
heat will still be either generated inside or will enter from outside.
After heat rejection and passive cooling systems have been integrated into the
building, mechanical systems can be considered- but not before. Mechanical systems
should be a last line of defense, not a given if at all possible. If they do need to be used
then the most efficient systems should be used so as to not negate the energy that the
passive strategies have saved. Using this approach to building the 40 quadrillion Btu of
energy spent on commercial and residential energy needs and the $11 billion spent on air
conditioning can be drastically reduced.
CASE STUDIES
There is no one size fits all approach to passive cooling. A building that is
designed perfectly for passive cooling cannot be replicated in a cookie cutter manner to
another location and be expected to function just as well as it did at the original site. This
is because passive cooling techniques are unique to the specific site, orientation, and
climate. Additionally, a building cannot just use one passive technique and be expected to
function well. A passively cooled building works best when multiple techniques work
together to create a cohesive whole. This means that an architect that wants to design
using passive cooling needs to know a wide variety of techniques that can then be
carefully selected based on the project. Rather than trying to list out all of the possible
techniques that can be used for passive cooling, the next chapter of this thesis will present
three different buildings that effectively use passive cooling as case studies. These case
studies can be used as references for how to approach different types of buildings, all of
which highlight different methods of approaching passive cooling.
The first building that will be discussed is the Zion Canyon Visitor Center in
Springdale, Utah. It is, as its name implies, a visitor center for Zion National Park in
southern Utah. It is the smallest of the three case study buildings and it is also very close
to being completely passively cooled. The Zion Canyon Visitor Center was chosen as a
case study because of the holistic approach to passive cooling that it used. It didn’t
concentrate on any one technique or any one type of technique; instead it utilized
overhangs, cooling towers, proper orientation, strategic space planning, etc. All of these
techniques are unique, but they all work together to make a cohesive whole.
The second building that will be discussed is the NREL RSF building. The NREL
RSF building is a very large commercial building that utilizes both passive cooling and
high efficiency mechanical systems. Due to its size and the amount of heat generated
inside by computers and people, the designers and engineers were unable to completely
passively cool the building complex. It is however, an excellent example of how
important windows are in passive cooling in terms of heat rejection. The NREL RSF uses
some very unique techniques that utilize both older techniques and some very new
techniques.
The third building that will be analyzed is the Boroujerdi House in Kashan, Iran.
The Boroujerdi House is a house that predates modern mechanical cooling systems, and
thus didn’t have the option to deny passive cooling as a powerful strategy altogether. This
drove the house to have several bold systems of cooling, all of which shape the building
in terms of how it was used and in terms of aesthetics. Its main features are the wind
towers, the courtyard, and the shading methods.
Through the analysis of these three buildings a wide variety of passive cooling
methods will be extracted that will be applied to a hypothetical winery in Utah that can
serve as an additional reference and example of how to design a passively cooled
building in Utah. From there the techniques demonstrated can then be used by others in
the building industry, from architects to homeowners, to be applied to their next building.
ZION CANYON VISITOR CENTER
Figure 6: North Face of Zion Canyon Visitor Center Source: Author 2015
The Zion Canyon Visitor Center is a passively heated and cooled building in
Springdale, Utah that acts as an information center for Zion National Park as well as the
first stop visitors make while in the park. People go to the visitor center to learn more
about the park, get water, use the restrooms, get permits, and to shop at the gift store,
among other things. Many trails begin there and the park’s shuttle system passes
alongside it to take visitors up the canyon. All of these activities result in a high amount
of foot traffic coming through the center as the park receives approximately three million
visitors per year, and upwards of 400,000 visitors per month during the summer
months31. Because of the high amount of foot traffic through the Visitor Center, passively
cooling the building became important to the owner, the National Park Service (NPS), as
a way to demonstrate the park’s dedication to being environmentally friendly and to serve
31 "Zion National Park Visitation: 2005-2015," table, NPS, October 19, 2015, accessed October 21, 2015, http://www.nps.gov/zion/learn/management/upload/ZION-VISITATION-2005-2015-2-2.pdf.
as an example of passive cooling techniques for future building. Many techniques, such
as cooling towers, people haven’t heard about or seen before, but when they visit the
Visitor Center these technologies are on display, with plaques explaining specific
functions and strategies.
Figure 7: Adaptive Architecture Visitor Sign Source: Author 2015
The Zion Canyon Visitor Center is sited in southern Utah, which is located in
climate zone 4, according to ASHRAE 90.1- 2013. Climate Zone 4 is a semi-arid climate
that has cold, windy winters and hot, dry summers32. The humidity is very low and in the
summer temperatures frequently exceed 90°F, with the 85°F being the average high in
May, 96°F in June, 101°F in July, 98°F in August, and 91°F in September.33 Because of
the low humidity there are large diurnal swings typically of 20-30°F from day to night,
32 Norbert Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable Design Methods for Architects, 4th ed. (Hoboken, NJ: John Wiley & Sons, Inc., 2015), [102-103]. 33 "Climate Data for Zion National Park," US Climate Data, last modified 2015, accessed October 22, 2015, http://www.usclimatedata.com/climate/hurricane/utah/united-states/usut0343/2015/1.
such as in June when the average high is 96°F and the low is 62°F. Additionally, the
annual precipitation is low with the region typically receiving about 15 in. per year.34 All
of these elements combined form a very hot and dry climate that has 1200-1500 cooling
degree days per year, which result in substantial cooling requirements that passive
cooling building strategies have to account for.35
Given the substantial cooling requirements of buildings in southern Utah, the fact
that the Zion Canyon Visitor Center has successfully mitigated the heat almost entirely
using passive systems is impressive and makes it worth analyzing. Additionally, the fact
that the building does not rely on a tight envelope to keep it cool, but rather that its
systems are powerful enough to compensate for the large influx of people each day that
are constantly opening and closing the doors, exposing the cool interior to the hot outdoor
air, lends to its success. This gives it credibility and draws attention because this means
that the building is fully capable of cooling itself without the perfect scenario, which in
turn makes the strategies used more flexible for application on other buildings.
In looking at the Visitor Center there are a wide variety of “common” and
“uncommon” solutions used such as: building orientation and window placement for
common solutions, and evaporative cooling towers as an uncommon solution. In having
both common and uncommon solutions in the same building the Visitor Center provides
a rich source to draw from when looking for ways to build passively in Utah. All of these
factors together make it an ideal case study and example of the way buildings could, and
should, be designed in Utah and beyond.
34 Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable, [102-103] 35 "Monthly Degree Day Comparison (Station UT4737)," table, 2015, accessed October 22, 2015, http://www.weatherdatadepot.com/.
Passive Systems
Building Orientation and Window Placement
One of the simplest and most straightforward ways to passively design is through
building orientation. For buildings north of the equator the south face of a building will
receive the most constant sun throughout the day. It is also where the most heat gain will
occur if there are windows on this building face. In contrast, the north face of a building
will receive the least amount of sun and is ideal for letting in diffuse or ambient daylight
without too much heat gain. The east face of a building is also good for letting in light
because, while it does get direct sun and could result in some heat gain, it is receiving
that direct sun in the morning when the outside air is typically cooler and the heat gain is
less prone to being negative. However, the same cannot be said for the west face of a
building. In the evening when the sun is setting any windows on the west face will
receive direct sun. Where east direct sun isn’t usually bad due to the cooler morning
temperatures, west sun is penetrating the building when the air is has already been well
heated during the hot daytime hours. The compounding of the two, hot outdoor air and
direct sun, can cause more discomfort and heat gain to the building.
Because the Zion Canyon Visitor Center is an envelope dominated building, using
the principles of building orientation to its advantage is very important to minimize solar
heat gain in the summer, maximize it in the winter, and to capture natural light. While not
every project has the luxury of being able to orient their building however they like, the
Visitor Center was able to be oriented to get the full benefit of the site. The Visitor Center
is broken up into two buildings: the main building with a gift shop, information desk,
offices, and a wilderness permit area, and the support building with restrooms. Both
buildings are oriented similarly because both are trying to accomplish the same goal;
minimization of heat gain.
The main building’s front façade faces north and is covered in more than 50%
glass, with the entrance doors being made of glass, as well as the walls that they are in.
The façade is covered in this large amount of glass because it allows daylight in, reducing
the need for indoor lighting, and because it also invites people in and makes it easily
identifiable as the entrance. On other faces, this amount of glass might not have been
conducive to minimizing solar heat gain, but because it is oriented northward, the large
glass façade is able to allow in light without additional heat gain. Not only does the
northward orientation of the glass help reduce its heat gain, but also its composition as it
is made from 1” thick insulated glass36 that has an R-value of 30 and features suspended
low-e films37. These features together in combination with the orientation help reduce
heat gain from the glass. The support building though has no glass on the north side
because it houses bathrooms.
Figure 8: Main Building North and West Façade, and Restrooms North Façade, Respectively Source: Author 2015
36 James Crockett, Zion Construction Drawings, illustration, PDF 37 Alex Wilson, "Zion National Park Visitor Center," Solar Today, May 2002, pg.34, PDF
The east side of the bathrooms is devoid of any openings due to privacy, while the
main building’s east side has several openings on its walls. One set of openings that exist
on the east side of the main building are clerestory windows. These are small windows
oriented horizontally in a ribbon along the top edge of the building just below the
roofline. The purpose of these windows will be discussed later, but in terms of orientation
and solar heat gain they don’t pose a problem because they are well shaded in the
summer by the overhang of the roof. The second set of east facing openings are the
windows for two offices. Normally these openings wouldn’t be a problem, but in the case
of the Visitor Center they tend to cause the offices to overheat due to how direct the sun
is when it shines in them. This is an example of having too much direct sun, even if it is
in the morning and isn’t typically a problem.
The treatment of the west side of the main building, insofar as windows and
opening are concerned, is quite varied. The front of the building has a zig-zag form where
it first faces north, then west, then north, then north-west, then north, then west. As
previously mentioned, the north faces are primarily glass and mullions, and this large
amount of glass continues along the front façade to the west and north-west faces as well.
West faces don’t usually do well having a lot of glass because they get direct sunlight in
the evening when the air outside and inside has already been heated. This problem is
addressed in two ways: One is an overhang and second is a special glass quality. Just like
the north facing glass, the remaining glass in the building is 1” thick insulated glass38
with suspended low-e films and a variety of R ratings depending on the needs and
38 James Crockett, Zion Construction Drawings, illustration, PDF
direction of the glass39. This, along with the overhangs, ensure that the glass areas do not
cause the building to gain much heat in the summer while still maintaining a continuous
glass façade.
In contrast, the set of windows on the west side of the building that run along the
gift shop are treated very differently from the glass along the north façade. There are
three windows that look out from the gift shop which aren’t that large and also have the
same insulated glass quality as applied elsewhere in the building. However, they do take
on a significant amount of heat gain in the space between the glass panels. This might be
seen negatively, but in fact the heating of the display space was intentional. The display
space is meant to heat up, forcing the air to rise up the cavity and out an opening at the
top. Because the air is flowing up and out of the display window it pulls with it the warm
air in the bookstore, which in turn draws cool air in from outside, creating a cycle of
induced ventilation. This cycle of induced ventilation creates a pleasant flow of air in the
building and keeps its interior cool. There are also shrubs and deciduous trees that are
planted right outside the windows to provide shade to the windows, thus the heat gain is
not excessive. During the summer months the plants’ leaves shade the windows; in the
winter they drop their leaves and allow the sun to enter the building and provide passive
solar heat gain at a time when it is cold outside. The support building does not have any
windows to the west dues to a need for privacy.
39 Alex Wilson, "Zion National Park Visitor Center," Solar Today, May 2002, pg.34, PDF
Figure 9: Main Building West Windows Source: Author 2015
The final face of both the main building and the support building is the south face.
The south walls for both buildings are addressed the same with respect to their openings.
Both buildings have trombe walls where the glass is blackened for solar heat gain in the
winter. To mitigate unwanted heat gain during the summer, overhangs provide the shade
necessary at a time of the year when the sun is high up in the sky, thus direct solar heat
gain is being cut out by the shading devices. Additionally, there are many different
deciduous plants ranging in height, which are planted directly in front of the trombe wall
to provide shade in the summer, or to let the sun in the winter. Not only are there trombe
walls on the south walls, but there are also clerestory windows, which are designed to
block significant amounts of heat due to the fact that they are small and also shaded by an
overhang that blocks the high sun in the summer and allows for solar heat gain during the
winter months.
Figure 10: South Side of the Main Building and Restrooms, Respectively Source: James Crockett 2000
In analyzing the Zion Canyon Visitor Center’s approach to building orientation
and window placement, architects of future buildings in Utah can learn the following
strategies: first, when orienting a building in this specific location and climate zone, it is
best to have the majority of windows and openings facing north because by doing so a
building captures the natural light without additional heat gain. Second, light and heat
gain on windows on the south or west facades can be controlled by natural vegetation,
external shading, and well insulated glass - all powerful strategies to ensure that the
building doesn’t overheat.
Window Overhangs
External window shading is the most effective technique that can be applied when
windows are needed for views, light, and ventilation. There are two different
implementations of overhangs at the Visitor Center, both providing a good case study for
overhangs. On one of the north walls there are two small windows that people can walk
up to, to receive wilderness permits. The roof above these windows extends and is
supported by two columns to create a small 12’x23’ shaded area just in front of the
building40. While not technically an overhang, it acts as an extension of an overhang and
shades the windows. This same technique is used on the north-west glass wall to keep it
fully in shade and to draw attention to it as the central entrance since there are a number
of doors you can enter the building through.
Figure 11: Overhangs Source: Author 2015
A general overhang of approximately 3’ runs around the perimeter of the
building, giving shade to all of the windows during the summer time. Finally, there is a 2’
overhang over the clerestory windows to ensure that they also get shaded properly41.
None of the overhangs look like they were tacked on later nor are they obtrusive. The
architects managed to integrate the overhangs well into the architecture; much like Frank
Lloyd Wright did with his buildings, so that in the end, when it comes to possible value
engineering, the overhangs will not fall victim to such as they are an integral part of the
design.
40 James Crockett, Zion Construction Drawings, illustration, PDF 41 Ibid
Natural Ventilation
Apart from heating and cooling, a major function of mechanical systems is
ventilation. Buildings need to be well ventilated and provided with fresh air for the
environment of its occupants to be healthy, as per the standards sets forth by ASHRAE.
ASHRAE defines acceptable indoor air quality as “air in which there are no known
contaminants at harmful concentrations as determined by cognizant authorities and with
which a substantial majority (80% or more) of the people exposed do not express
dissatisfaction.”42 In order to provide acceptable indoor air quality three different systems
were used: clerestory windows, fans, and a minimal ventilation system. These systems all
work in tandem to provide good ventilation, but clerestory windows are by far the most
beneficial in the hot summer months as they play double duty by also aiding in the
passive cooling of the building.
The clerestory windows are used in conjunction with lower windows, and a
computer operated system to open and close them based on the building’s needs. The
computer system installed is called Delta43, and it communicates with a weather station in
Cedar City, using Zion National Park data, and NREL data44 to know when to open, and
when to close each set of windows for the maximum benefit. This system works well
because cool air is brought into the building when the lower windows are open, and is
allowed to escape through the clerestory windows on the south end of the building when
it heats up. This process is aided by the angling of the ceiling which goes from 9 feet to
20 feet, from north to south. This style of ceiling works well with natural ventilation
42 "Definitions," in ANSI/ASHRAE Standard 62.1-2013: Ventilation for Acceptable Indoor Air Quality, 62.1- 2013 ed. (Atlanta, GA: ASHRAE, 2013), 3, digital file. 43 Earl Cox, interview by the author, October 21, 2015 44 James Crockett, e-mail interview by the author, October 27, 2015
because the cool interior air eventually heats up and rises. When it rises it hits the ceiling
and is directed by the slope of the ceiling upward to the clerestory windows on the south
end of the building. With the ceilings so high on the south end the hot air is well above
the visitors below and if the clerestory windows are open the air can continue up and out
the windows. This cycle of bringing in cool air from the lower windows and directing it
out through the clerestory windows when it heats up creates a gentle flow of air that
naturally ventilates the building, gives a cooling feeling to visitors, and lowers the overall
temperature in the building. This system doesn’t fully ventilate the building, especially on
the days when the windows need to be shut to retain either hot air in the winter or cool air
in the summer. In this case the ventilation system brings in fresh air from outside, the 13
fans inside circulate it through the building, and then the ventilation system can push the
stale air back outside45.
Night Flushing
On days when the outdoor air temperature is higher than the desired indoor air
temperature the lower windows might stay closed because the air they would bring in
heats the building instead of cooling it. When this happens the large diurnal swings of the
arid climate are utilized through a technique called active night flushing. Night flushing
works by opening windows when the sun has set and the outside temperature starts to
drop. Since the Zion Canyon Visitor Center is located in an arid climate zone diurnal
swings can be between 20-30°F, with the 30°F swings most common in the summer. This
45 Earl Cox, interview by the author, October 21, 2015
places the outside air temperature as low as 62°F during the summer nights.46 Given this
large swing in temperature the Visitor Center’s computer system opens the windows and
starts to cool down the building’s thermal mass that has been charged with heat energy
during the daytime. Once the mass has been cooled down, the cool outside air can be
trapped inside by closing the windows, so that when the temperatures start to rise outside
the air inside is still cool.
Cold Roof Design
One part of a building that often receives little attention in reducing cooling loads
is the roof. Currently, a very popular way to cover a roof is with black asphalt shingles,
which isn’t a very environmentally conscious choice because it causes the roof to gain a
lot of heat which then radiates back into the interior of the building through the ceiling.
To combat this effect and to be consistent with the surrounding park architecture the roof
was clad in brown wood shingles that over time have faded to a grey color, which better
reflects the sun instead of absorbing it. To further repel the roof from gaining heat it is
made from structural insulated panels (SIPs) that have a ventilated air space between the
SIPs and the roof sheathing that allows warm air to escape instead of radiating back to the
interior.47
46 Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable, [102-103] 47 James Crockett, e-mail interview by the author, October 27, 2015
Thermal Massing
When the building is cooled by night flushing not only is the air cooled, but the
materials within the building also lose heat and become cooler. Some materials, such as
wood, are very susceptible to temperature changes and gain and lose heat rapidly. This
doesn’t do much in the way of aiding in the cooling of the building; however other
materials such as concrete and masonry have a dense mass and are slower to absorb and
release heat or cold, which can have a desirable effect on the heating and cooling of any
building. These materials are described as thermal mass. Often, thermal massing is used
on the walls of buildings, but in the case of the Zion Canyon Visitor Center it is used on
the floors as well. This thermal mass works in two ways- it supports cooling in the
summer and heating during the winter. The thermal mass used for cooling in the summer
are the building’s polished concrete floors which, through night flushing and being in
contact with the earth, become quite cool. Additionally, there is stone on some walls that
can also absorb heat from the air just like the concrete floor causing it to be a heat sink
during the day48. This helps cool the building in a small way, but it certainly adds up in
the grand scheme of the building.
Building Massing
In an effort to reduce construction costs and to lower the overall need for cooling
energy the Visitor Center was broken up into two buildings, the comfort station
(bathrooms) at 2,756 square feet and the main building at 8,475 square feet. The square
48 Alex Wilson, "Zion National Park Visitor Center," Solar Today, May 2002, pg.34, PDF
footage of the two buildings together is about 7,500 square feet less than the original plan
for the Visitor Center because the majority of the exhibit and circulation space was
moved outdoors. The climate in Zion National Park is very dry with the area receiving
an average of 15 in. of precipitation per year. Moving the display exhibits outside works
well for the Visitor Center because for the majority of the peak visitor season there is
little worry of bad weather that would impede visitors from using the outdoor space. Each
of the ten exhibit spaces is shaded by a pergola, and many are surrounded by some sort of
vegetation that can provide a measure of shade. There is also a small historic irrigation
ditch that looks like a small creek that runs in-between the two buildings and creates a
cooler micro-climate due to the evaporative cooling effect it creates, and the addition of
humidity to the air. Moreover, by separating the bathrooms from the main building the
circulation space is now placed outside, further reducing the total square footage. This
means that there is significantly less space to heat and cool, and results in less passive
systems being needed and lower overall costs. Also the reduction in space meant a
serious reduction in embodied energy for additional construction materials, a lower CO2
footprint due to less material being hauled to the site, and more.
Figure 12: Site Plan and Pavilions Respectively Source: Author 2015
Evaporative Cooling Towers
While many strategies used in the building help with cooling, the largest and most
important strategy is the use of cooling towers. The cooling towers function like large,
naturally driven swamp coolers49 and stand 31 feet tall. The way they work is that on the
top of the towers there are vents on each of the four sides measuring approximately 5’ tall
by 6’ wide50. These vents are also controlled by the Delta computer system that opens
and closes the windows in the building. Using a nearby weather station and internal
building data, such as the interior temperature, the system knows when cooling is
required. When it is determined that cooling is needed the vents on the top are opened to
let in outside air, which is typically hot. There are no fans in the cooling towers to draw
in the air since the towers are tall enough to take advantage of the fact that air moves
faster the higher off the ground it is, due to less friction being present51. This results in a
substantial flow of air at 8000 cubic feet per minute52. Additionally, the Visitor Center is
situated in a canyon that experiences a lot of wind, and because the cooling towers have
vents on all four sides it can capture wind from any direction. Once the air is drawn in, it
is directed over a water soaked pad, which is provided with water by a small pump, the
only mechanical part in the otherwise all natural system. When the air flows over the
water soaked pad it cools down and becomes more humid. This causes the air to becomes
more dense and fall down the tower. When it gets to the bottom of the tower it can either
flow outside to the patio area or it can be directed into the building’s lobby. This is
controlled by a second set of vents at the bottom of the towers that are opened and closed
49 Earl Cox, interview by the author, October 21, 2015 50 James Crockett, Zion Construction Drawings, illustration, PDF 51 Earl Cox, interview by the author, October 21, 2015 52 Alex Wilson, "Zion National Park Visitor Center," Solar Today, May 2002, pg.34, PDF
by the computer system. The cooling towers work extremely well and are the largest
contributors to overall cooling in the building because of their ability to drop the air
temperature up to 30°F53.
Figure 13: Cooling Tower Exterior and Interior Source: James Crockett 2000
Not only are the cooling towers a key factor in regulating the building’s
temperature, but they are also key to the building’s overall aesthetic look. Overall, three
cooling towers define the aesthetics of the project- two on the main building, and one on
the support building. When visitors park before entering the Zion National Park they can
spot the Visitor Center pretty easily because of the cooling towers that can be seen in-
between the trees. The building as a whole would not read the same without them.
53 Kim Sorvig, "Renewing Zion," Landscape Architecture, February 2002, pg.72-90, PDF
Effectiveness
Even with an entire host of passive systems installed, and window sized and
oriented correctly, there is still the possibility that such a passive, yet complex system
might not fully function. This section will be discussing the degree to which the passive
systems work in the Zion Canyon Visitor Center.
As a whole, the Zion Canyon Visitor Center is not 100% passive. It is however
mostly passive, with exception of its cooling towers, which use a small pump to keep the
water pad wet, and the natural ventilation system, which uses small motors to open and
close the windows. However, using such a strict definition of passive is not a good way to
go about rating a system because each of those small motorized features uses only a small
amount of energy, which is negligible in comparison to a traditional mechanical system.
For example, the pump that runs water over the cooling pad runs on a 15 amp circuit in
comparison to a traditional air conditioning system that runs on a circuit of 100 amps or
more.54 Additionally, ASHRAE, the organization that sets the standards in the United
States for heating, cooling, and refrigeration defines mechanical ventilation as
“ventilation provided by mechanically powered equipment, such as motor-driven fans
and blowers, but not by devices such as wind-driven turbine ventilators and mechanically
operated windows.”55 By this given definition I would say that both the windows and the
cooling tower are not mechanical passive systems, but rather straight passive systems.
There is however one small part of the Visitor Center that is undeniably
mechanical, the offices. As a result of a last minute design change prior to construction,
54 Earl Cox, interview by the author, October 21, 2015 55 "Definitions" In ANSI/ASHRAE Standard 62.1-2013: Ventilation for Acceptable Indoor Air Quality, 2. 62.1- 2013 ed. Atlanta, GA: ASHRAE, 2013. Digital file.
two of the offices in the main building were moved against the trombe wall. The trombe
wall originally had a well sized buffer space between the wall and the offices, because of
the heat that it gives off- even during the summer months. The buffer space was supposed
to mitigate the extra heat that it gives off, with the passive systems supposed to take that
heat outside the building. However, due to the last minute change to have two offices
against the wall, the passive systems are not capable any more to properly cool the
offices- they overheat in the summer. This is due to the fact that the offices are entirely
enclosed and are located directly on a strong heat source. As a result, and despite the fact
that the client wanted to keep the building fully passive, the only solution was to install a
small air conditioning unit in each office56. This happened after construction and
occupation and was received as very unfortunate.
With regards to only the passive systems in the building, which account for the
majority of the two buildings, the systems work exceptionally well. In speaking to two
employees that have worked in the Visitor Center for multiple summers, their general
consensus is that the systems work great with the exception of a handful of days in the
summer. The first employee interviewed had worked at the Visitor Center for five years
and loved the way that the cooling towers worked. She said that it can get so cool that
she’ll put on a light jacket. When asked about the average temperature in the building she
said that it was typically in the mid to low 70s and that at the highest it only ever got to
the high 70s.
The second employee that was interviewed had worked at the Visitor Center for a
few years and also echoed the first employee in his satisfaction with the system; he had
56 Earl Cox, interview by the author, October 21, 2015
high praise for the overall comfort level of the building. When asked if the systems ever
failed he said that they did, but only a few days each summer when it rains. He said that
the cooling towers didn’t work well when the humidity outside rises, which was usually
during a storm.
Based on the interviews, visiting the site, speaking to the project architect James
Crockett, and speaking to Earl Cox, the HVAC systems manager for Zion National Park,
it can be concluded that the Zion Canyon Visitor Center has been very successful in its
attempt at being a passive building.
Implications
Aside from keeping the visitors and workers cool during the summer months,
there are a few additional implications and positive results of using passive systems. The
first result of having a passively heated and cooled building is a large cost savings. The
Visitors Center’s annual cost savings having it designed passively instead of utilizing
common mechanical systems is $14,000 per year,57 with the buildings using 26.9 kBtu
per square foot per year and having operating costs of $0.45 per square foot58. These cost
savings comes from a 64.4% reduction in heating, 95.6% reduction in cooling, 73.6%
reduction in lighting, 43% reduction in plug loads, and 91.7% reduction in fans, all of
which add up to a 74.4% total reduction in energy use.59 All of these savings happened
57 "Zion Canyon Visitor Center," National Park Service, accessed October 30, 2015, http://www.nps.gov/zion/learn/nature/zion-canyon-visitor-center.htm. 58 Paul Torcellini, Ron Judkoff, and Sheila Hayter, Zion National Park Visitor Center: Significant Energy Savings Achieved through a Whole-Building Design Process (n.p.: National Renewable Energy Laboratory, 2002), pg.8, accessed October 30, 2015, http://www.nrel.gov/docs/fy02osti/32157.pdf. 59 "Zion Canyon Visitor Center," National Park Service, accessed October 30, 2015
without any additional construction costs, in fact the building came in well under budget.
This lowering of construction costs came primarily from the fact that little to no
mechanical systems were needed, and thus the infrastructure typically needed from that
was eliminated along with the cost associated with that. Additionally, the building is
lower in cost because it is 7,500 square feet smaller than what it could have been due to
the moving of exhibitions and some circulation space outside.
The lowering of costs and achieving overall user comfort within the building are
great accomplishments, but it should not be forgotten that the building is also being
environmentally friendly. When a building’s design provides an opportunity to decrease
its overall footprint physically, also terms of energy consumption, it is doing a great
service to the environment.
Conclusion
The Zion Canyon Visitor Center is an excellent example of how buildings in Utah
can be designed to function passively. The use of common systems such as building
orientation, window placement, natural ventilation, operable windows, night flushing,
and overhangs are great examples that many buildings should, and can, easily integrate
into their design. These techniques are as simple as specifying that a window be operable
instead of fixed, and architects that don’t use these techniques are missing very simple
strategies to cool their building. Other less common systems that are a bit more building
and site specific are cooling towers, cold roof design, strategic use of deciduous
vegetation, thermal massing, and the reduction of the overall building footprint. These
techniques are innovative and can result in a large impact on the energy consumption of a
building. The two techniques that buildings in Utah should consider given Utah’s dry
climate are the use of cooling towers and active or passive night flushing. Cooling towers
don’t work well in humid climates, but because Utah has an annual dry climate, more
buildings should consider using them as they have the ability to cool down air up to 30°F.
Night flushing can be applied both as a user initiated technique and/or as a design
element. It can be a design element by specifying that windows be operable so that night
flushing can occur with user participation, or it can be fully integrated in the design by
doing what the Visitor Center did and having the opening and closing of windows be
automated. Either way, night flushing is great for Utah because of the large diurnal
swings from day to night. Given its excellent passive systems and outstanding
performance compared to the code-standard building, future buildings in Utah should
look to the Zion Canyon Visitor Center as a case study and reference building.
Continuing to design buildings that ignore the climate and site and regional context will
waste the limited resources that are available to us on a regional, national and global
level. Furthermore, the savings of building passively are so great that there is no good
reason to not use at least one technique presented by the Zion Canyon Visitor Center.
NREL RSF
Figure 14: NREL RSF Rendering Source: RNL Design 2010
The NREL RSF (National Renewable Energy Laboratory Research Support
Facility) is a large research support facility with 360,000 square feet of interior space60
that was designed to demonstrate a variety of innovative passive and active systems to
heat and cool the building. This was important to the design of the building because
NREL is a federal laboratory that partners with private industries, federal agencies, state
and local governments, and international groups and is dedicated to the research,
development, commercialization, and deployment of renewable energy and energy
efficiency technologies.61 It would be contradictory to NREL’s mission of researching
and developing renewable energy if their own building was harmful to the environment
and didn’t seek to actively reduce the building’s energy loads. The dedication to first
reducing the building’s energy needs passively and then addressing the remaining energy
needs with renewable energy instead of exclusively using renewable energy is
commendable. Additionally, the success that it has had with its goal of making the
building net zero makes it a great case study for passive cooling techniques.
60 "Research Support Facility," NREL, last modified January 9, 2014, accessed November 28, 2015, http://www.nrel.gov/sustainable_nrel/rsf.html. 61 "Mission and Programs," NREL, accessed November 5, 2015, http://www.nrel.gov/about/mission-programs.html.
The NREL RSF building is located in Golden, Colorado, 15 miles west of
Denver, Colorado. The local climate in Golden is a cold semi-arid steppe climate.62 This
means that a large majority of the year is cold, however it still gets hot in the summer,
although not nearly as hot as it gets in southern Utah. This also means that it is fairly dry,
especially in July when three out of four days the relative humidity is below 27%. The
warm season lasts from mid-June to mid-September when the average daily high is
around 80°F.63 These factors make the climate in Golden slightly cooler, but comparable
to Utah’s climate.
Not only was the NREL RSF building built in a semi-arid climate that is similar
to Utah’s, it also has similar cooling needs that a large scale commercial building in Utah
would have. These cooling needs are primarily dealt with by keeping the building from
gaining heat in the first place. The large majority of these techniques are employed
through the strategic design of the windows.
Passive Systems
Orientation and Windows
In order to keep the NREL RSF building from gaining heat a combination two
main techniques was used; thoughtful orientation and massing, and the strategic design
and placement of windows. To start with, the building was built as three long 60’ wide
bars that are oriented along the east-west axis so that the majority of the windows are
62 "Average Weather For Denver, Colorado, USA," Weather Spark, accessed November 6, 2015, https://weatherspark.com/averages/30040/Denver-Colorado-United-States. 63 Ibid
facing either north or south.64 The windows that do face east and west are off conference
rooms and are utilized as examples of advanced window technology. The east window is
thermochromic and the west window is electrochromic. Only the east window with its
thermochromic treatment would be considered a passive strategy as electrochromic
technology uses electricity to tint the window. Thermochromic windows are made to
resist to heat transfer more than standard glass to reduce heat gain65 and the balconies
that are in front of them are recessed which provides shade to the windows.66
Figure 15: Recessed Balconies Source: Dennis Schroeder 2011
Like the east-west windows the north-south windows are specially treated to
minimize heat gain through a number of methods. The first method is simply making sure
that the window-to-wall ratio is not too high. If the intent is to reduce heat gain or heat
loss then a lower window-to-wall ratio is an effective way of doing this due to the
64 US Department of Energy NREL. Research Support Facility—A Model of Super Efficiency. 2010. PDF 65 Bill Glover, The Road to Net Zero (NREL, 2011), 23, PDF 66 The Design-Build Process for the Research Support Facility (NREL, 2012), 9, PDF.
generally lower R-values of glass and its conductivity to heat gain in the summer and
heat loss in the winter. Due to this quality of glass it was decided that the window-to-wall
ratio for the north and south walls would be approximately 25%.67 The window-to-wall
ratio of the two walls isn’t exactly 25%, as the north wall has slightly larger windows,
however it can be approximated to 25%. This 25% ratio still allowed for good views,
good daylighting, and natural ventilation to be integrated into the building.
Figure 16: Window to Wall Ratio Source: John De La Rosa 2015
Even though the window-to-wall ratio is low there are still quite a few windows
on the north and south faces of the building because of the large amount of exterior wall
space that the building has. As such, there is still a substantial amount of heat gain that
the windows, if not properly treated, could bring to the building. To ensure that this does
not happen all of the south windows are triple glazed, have thermally broken frames,
have individual overhangs to shade them, and are smaller than the north facing windows.
The windows are divided into two parts with the top part of the window called the
daylighting glass and the lower portion is called the vision glass. The lower vision glass
is the part that has the individual U-shaped shade surrounding it to protect both from
67 The Design-Build Process for the Research Support Facility (NREL, 2012), 8, PDF.
glare and heat gain. The upper daylighting glass is fitted with highly reflective horizontal
louvres that deflect direct sunlight to the ceiling which then diffuses the light to the
interior workspace, keeping it both well-lit, at the same time keeping the heat out. The
north facing windows are also triple glazed and have thermally broken frames, but they
are larger in size and are not shaded by either louvres or individual overhangs due to the
fact that north light is more diffuse and less prone to contributing to heat gain.68
Figure 17: Windows and Louvres Respectively Source: Dennis Schroeder 2010
Natural Ventilation
In addition to reducing heat gain, the windows also contribute to the cooling of
the building through natural ventilation. On both the north and south windows the lower
portion of the windows can be manually and automatically opened, and on the north
windows the upper portion can be automatically opened. When the weather is mild
enough the workstation based task manager notifies occupants that the weather is optimal
68 The Design-Build Process for the Research Support Facility (NREL, 2012), 12, PDF.
for natural ventilation and suggests that they open the windows. This provides an
opportunity for the occupants to be involved and aware of the passive cooling that is
going on in the building. In the event that the occupants do not manually open the
windows when the weather permits natural ventilation, the computer system will
automatically open the windows.69 Either way, the building and the occupants benefit
from the effects of natural ventilation.
Figure 18: High and Low Windows Source: Dennis Schroeder 2011
Another way that the building is optimized for natural ventilation is through its
shape. Buildings that are too wide may not be able to have effective cross ventilation, but
with the NREL RSF building’s depth of 60’, which was determined to be the optimal
69 The Design-Build Process for the Research Support Facility (NREL, 2012), 12, PDF.
depth for allowing and encouraging cross ventilation, the building can take advantage of
this passive strategy during specific times of the year.70
Night Flushing
Not only is natural ventilation good during the day, it is also great at night.
Golden, Colorado, like Utah, experiences diurnal swings of 20-30°F from day to night.71
The top portion of the automated windows on the north and south walls open when the
weather conditions are optimal for night flushing.72 Night flushing allows the hot air to
escape the building when the air outside is cooler than the air inside. It also allows the
thermal mass inside the building to cool down so that it can absorb heat during the day
instead of the interior air heating up. Successful night flushing cools the building at night,
without mechanical systems, and allows the occupants to enter a cool building in the
morning.
Effectiveness
Prior to the construction and occupation of the NREL RSF numerous models were
made to predict the energy needs of the building and how the passive and renewable
active systems would work together to heat, cool, and power the building. It was
predicted that with the data center, a large consumer of energy, the building would
70 The Design-Build Process for the Research Support Facility (NREL, 2012), 9, PDF. 71 "Climate Golden- Colorado," US Climate Data, accessed November 9, 2015, http://www.usclimatedata.com/climate/golden/colorado/united-states/usco0553 72 The Design-Build Process for the Research Support Facility (NREL, 2012), 8, PDF.
consume 35.1 kBtu/ft²/yr. To date the building uses 35.4 kBtu/ft²/yr, which is slightly
higher than the predicted value due to the building having higher heating needs than
expected.73 Overall this is an 81% reduction in power requirements over other buildings
of comparable size, occupancy, and use.74 By offering operable windows, excessive heat
gain is avoided, as it also encourages natural ventilation and allows for night flushing,
which is just one of many passive systems used throughout the building to cool and
reduce power requirements. While there are no numbers specifically for the effect that the
windows have on lowering the need for cooling power it is very telling that the building
only uses 0.85 kBtu/ft²/yr on space cooling.75 To set this number into context, the NREL
RSF uses 35.1 kBtu/ft²/yr on general energy consumption, of which 2.5%- 0.85
kBtu/ft²/yr- is used for space cooling. A typical commercial building of similar size and
location that has an Energy Star rating of 90, such as the EPA Region 8 office in Denver,
Colorado, uses approximately 65 kBtu/ft²/yr.76 On average a commercial building uses
14% of its total energy use on space cooling, which would mean that the average energy
conscience commercial building might use 9.1 kBtu/ft²/yr. However, a more typical large
office building that is not as concerned with energy consumption, and has an Energy Star
rating of 50, would have an energy consumption of 115 kBtu/ft²/yr.77 This means that the
energy spent on space cooling would be 16.1 kBtu/ft²/yr. Given a typical cooling energy
load of a large office building, the NREL RSF sets a high bar for what can be achieved in
future commercial buildings.
73 NREL’s Research Support Facility: An Energy Performance Update (NREL, 2011), 2, PDF 74 Bill Glover, The Road to Net Zero (NREL, 2011), 32, PDF 75 NREL’s Research Support Facility: An Energy Performance Update (NREL, 2011), 6, PDF 76 Ibid 77 Ibid
An unexpected effect that the windows have on the cooling and comfort of the
indoor environment is in mitigating humidity. One of the other passive systems used in
the building is evaporative cooling, which is effective for the majority of the hot months.
However, the occupants are bothered by the increase in humidity, even though the
humidity levels meet the ASHRAE Standard 55, because they are used to a much drier
climate in Colorado. This is solved by lowering the humidity levels of the evaporative
coolers and by the use of the operable windows to get rid of the unwanted humidity.78
This is an unexpected side-benefit of operable windows that many people might not
realize; the ability to help balance occupants’ comfort in the indoor environment when it
is too dissimilar from the outdoor environment. It may not seem like a passive cooling
strategy by itself, but the ability to help balance out other passive systems by individual
needs and initiatives makes the operable windows very useful and aids in the overall
cooling of the building.
Implications
While there are many other passive cooling systems used in the NREL RSF
building the windows are of particular interest because of their widespread applicability
for Utah buildings, and many other buildings beyond. Nearly every building has windows
on one or more of its walls, and depending on how they are designed they can either
support or impede a cooling strategy of the building. This is especially true of recent
construction where the new trend is toward having more than 30% glass on one or more
walls to promote a variety of things such as transparency and aesthetics. While this may
78 The Design-Build Process for the Research Support Facility (NREL, 2012), 52, PDF.
look great, it really shouldn’t be happening on any building that seeks to be
environmentally friendly and that has hot summers or cold winters because of the
massive heat gain that glass has in the summer and the heat loss in the winter. In Utah in
particular buildings will incur large heat gains if windows aren’t designed correctly.
There shouldn’t be large unshaded south and west facing windows on buildings that want
to use passive cooling, or on any other in general. Buildings in hot climates should either
include exterior shading strategies or avoid large window-to-wall ratios on all east, west,
and south facing facades.
In addition to not overloading a building with glass there are many different
window techniques that can be implemented from the NREL RSF into many other
buildings. The first is highly insulated glass or specially treated glass such as
thermochromic glass. Both the Zion Canyon Visitor Center and the NREL RSF use thick,
insulated glass because single pane glass is a major conductor of heat, thus a leak in any
building’s walls and need to be a thing of the past. The more insulated the glass, the less
of a liability the glass will become. The second technique is to shade the windows. If a
window is well shaded on its outside then it significantly reduces heat gain and an overly
bright interior. A window can be shaded a number of different ways such as roof
overhangs, vertical louvres, and horizontal louvres. The next technique is to allow the
windows to aid in natural ventilation and night flushing by making them operable. As
long as the nighttime temperatures drop below the interior temperature of the building
then a building has the potential to benefit from night flushing. Even if the nighttime
temperatures outside don’t drop below the interior temperatures, many buildings can
benefit from having fresh air moving through the building. Each of these window
techniques can be implemented in a wide variety of other buildings to create an overall
cooler building. They won’t fully cool the building on their own unless the climate is
very mild, but they will go a long way towards reducing the initial cooling load that the
building has as well as aiding other systems of passive cooling by contributing natural
ventilation.
BOROUJERDI HOUSE
Figure 19: Boroujerdi House Courtyard Source: Ramin Hejrat 2009
The Boroujerdi House is located in Kashan, Iran and is a traditional Persian four-
season house that was built in 1876 by architect Ostad Ali Maryam Kashani. The house is
very large with the lot being 18,300 square feet because the owner Haj Seyed Hassan
Natanzi, was a wealthy merchant and the house was made for a large family to live in.
The house was designed as a semi-detached courtyard style home, which was the typical
style of the surrounding houses.79
79 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185.
Thirty years ago the house was renovated to include electricity and it is now used
as the cultural heritage office of Kashan80 and serves as a public museum81. Back in 1876
when it was originally constructed it did not have any mechanical systems, as they had
not yet been invented. The only energy that was used in the house was wood and charcoal
for heating, and lanterns for lighting.82 Because the building predates modern mechanical
heating and cooling systems it was climatically designed in accordance with the region so
that it could mitigate the harsh desert climate to keep its occupants comfortable. This
comfort is achieved by modulating the conditions through the use of carefully planned
spatial organizations and passive ventilation systems. These systems and spatial
organizations are expressed through its courtyard design and through the inclusion of
three wind towers, along with a dome that acts like a fourth wind tower. Due to this
unique approach to passive cooling the Boroujerdi House will act as the third case study
for passive cooling for this paper.
The Boroujerdi House is located in Kashan, Iran at 34° N latitude and 3100 feet
above sea level. Kashan has a hot and arid climate83, with annual precipitation typically
being around 5 inches84. During the hot months (June-September)85 there is
approximately 0.05” of precipitation86, and the average daily high is 93°F, with the
80 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 81 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html 82 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 83 Ibid 84 "Climate: Kashan- Climate Table," table, Climate-Data, accessed November 17, 2015, http://en.climate-data.org/location/715146/. 85 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran. 86 "Climate: Kashan- Climate Table," table, Climate-Data, accessed November 17, 2015, http://en.climate-data.org/location/715146/.
highest average daily high being 105°F, which occurs in mid-July87. During the warm
months (March-May, October-November) the average daily high is above 65°F88 and the
area receives an average of 2.86” of precipitation89. The rest of the year is cold
(December-February) and average temperature falls below 65°F, but it seldom gets below
30°F on average90. This leaves the large majority of the year (March-November) cooling
dominated. Due to the low amount of humidity in the air Kashan experiences moderate to
large diurnal swings. The diurnal swings aren’t as large as Utah’s diurnal swings, which
tend to be 20°F-30°F91, but rather they are on average 20°F. In May the highs average
93°F and the lows average 69°F. In July the highs average 105°F and the lows average
81°F. In September the highs average 93°F and the lows average 67°F.92 These swings
aren’t as extreme as the ones in Utah, and don’t get below the cooling degree threshold of
65°F, but they are still significant enough to be harnessed for passive cooling techniques.
As previously stated, the amount of precipitation that the area receives is very
low, with the average annual amount being 5 inches and the amount during the hot
months being only 0.05”.93 Additionally, during the warm season there is a 2% average
chance that precipitation will occur at some point during any given day. As far as
87 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran. 88 Ibid 89 "Climate: Kashan- Climate Table," table, Climate-Data, accessed November 17, 2015, http://en.climate-data.org/location/715146/. 90 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran. 91 Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable, [102-103] 92 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran. 93 "Climate: Kashan- Climate Table," table, Climate-Data, accessed November 17, 2015, http://en.climate-data.org/location/715146/.
humidity goes, the amount can fluctuate, but in general it is fairly low as seen in mid-July
when three out of four days the humidity is below 15%.94
Kashan receives some wind, however, it is not typically very strong or from any
predominant direction. Over the course of the year typical wind speeds vary from 0 mph
to 12 mph (calm to moderate breeze), and seldom exceeds 20 mph (fresh breeze) insofar
as averages go.95 Kashan being a desert city there are times that large gusts of wind blow
in from the desert and dust storms occur.96
In comparison to Utah, Kashan is more cooling dominated and has a longer and
drier warm season with diurnal swings that are about 10°F less Utah’s. These differences
make Kashan an ideal case study climate because it is a further exaggeration of the
climate in Utah. This exaggeration means that the passive systems used have to be even
more efficient and have to work for a larger portion of the year. The systems developed
in this region arguably have the potential to work even better in Utah’s climate because it
is less extreme, if only marginally.
Passive Systems
Orientation, Windows, and Seasonal Living
Like the NREL RSF building the Boroujerdi House first seeks to reduce its heat
gain, then implements systems and design techniques to address the remaining cooling
94 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran. 95 Ibid 96 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185.
load. This design approach places a lot of emphasis on the building orientation and
windows, as windows are one of the largest sources of heat gain if done wrong. To
generally lower heat gain from windows, the optimal building orientation is east-west,
with the windows facing north and south. The Boroujerdi House, however, was
constructed as a long rectangle with the long axis running roughly north to south.97
Figure 20: Ground Floor Plan, Site Plan, and 3D View of Boroujerdi House Source: Studio Integrate 2014
Normally this would not be a positive action, but the way that the building’s
windows are positioned, and the way that the house as a whole is laid out makes the
north-south orientation actually optimal. The reason that a north-south orientation is
typically negative is because the building is extroverted with the windows facing
outwards, and thus catching east and west sun. The Boroujerdi House however, is
introverted98 with no exterior windows. All of the windows are facing inward toward the
97 Michael Hensel et al., "Towards an Architectural History of Performance: Auxiliarity, Performance and Provision in Historical Persian Architectures," Architectural Design 82, no. 3 (May/June 2012): 36, accessed November 24, 2015, doi:10.1002/ad.1402. 98 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html.
central courtyard.99 The central courtyard is a large rectangular shaped outdoor space
with a pool in the center and is surrounded by trees and flowerbeds.100
Figure 21: Central Courtyard Source: Arian Zwegers 1999
Nearly all of the rooms in the house are facing the courtyard and they are all
connected to each other.101 This is to get light into each room through their window
facing the courtyard, and to take advantage of the cooler microclimate that is generated
there. The light that many rooms receive is diffused and indirect so that they can be well
99 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 100 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html. 101 Michael Hensel et al., "Towards an Architectural History of Performance: Auxiliarity, Performance and Provision in Historical Persian Architectures," Architectural Design 82, no. 3 (May/June 2012): 36, accessed November 24, 2015, doi:10.1002/ad.1402.
lit, but not excessively gain heat.102 This is accomplished by a covered arcade that
surrounds the courtyard and serves as an intermediary space between the courtyard and
the rooms. The arcade provides shade, encourages natural ventilation, and provides a
shaded place to walk.103 The original residents of the house occupied the house in a
seasonal manner, which means that the entirety of the house was not occupied year
round. The southern part of the house was the summer residence and the northern part of
the house was the winter residence.104 The southern part of the house, as previously
stated, doesn’t have any exterior windows and thus doesn’t get southern sun. The
windows on the northern part of the residences and are shaded by the deep covered
arcade, resulting in diffused natural light and no direct light. This is one of the elements
that keep the southern part of the house cool in the summer. The winter residences in the
northern part of the house also have no exterior windows, and their only windows face
south into the courtyard. There is no covered arcade in front of those windows so that in
the winter the sun is allowed to penetrate the rooms and warm them.105 The east and west
facing windows do, however, have covered arcades in front of them because they could
incur a large amount of heat gain if not properly shaded.106 There are covered arcades
shading the windows on three out of four sides because the goal of the house is to have
the majority of it kept cool due to the fact that nine months out of the year need cooling
instead of heating.107 This method of seasonal living does make portions of the house
102 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html. 103 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html. 104 Ibid 105 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html. 106 Ibid 107 "Average Weather For Kashan, Iran," Weatherspark, accessed November 17, 2015, https://weatherspark.com/averages/32804/Kashan-Esfahan-Iran.
unusable for parts of the year, such as the northern part in the summer, but it does create a
portion of the house that is cool and comfortable in the summer.
Thermal Mass
In order to keep the heat out of the house during the day the Boroujerdi House
was built with thermal mass. This thermal mass is seen in nearly every part of the house:
from the walls, to the floors, to the roof, which are all primarily built out of brick, adobe,
and stone.108 The walls, vaults and domes in particular demonstrate just how much
thermal mass the building has. They are all load bearing, and the walls in particular are
nearly two feet thick.109 The house’s thermal mass creates a time lag which allows the
walls to absorb and store the solar energy during the day, and release it at night. This
allowed the residents to comfortably occupy and use the house during the day. At night
though, the thermal mass was radiating the heat that it had stored during the day back into
the house, making it too hot to sleep in. Because Kashan has a very dry climate where it
seldom rains in the summer110, the family would sleep outside during the warm and hot
months of the year.111 At night it would be cool enough outside that it would be
comfortable to sleep and the courtyard provided a safe and protected place in which to
sleep. When the family would wake up in the morning the thermal mass would be ready
to be recharged, and the interior would be cool. The idea of not having the entire house
108 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html. 109 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 110 "Climate: Kashan- Climate Table," table, Climate-Data, accessed November 17, 2015, http://en.climate-data.org/location/715146/. 111 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185.
cool at all times is in direct contrast to how most people today expect buildings to
operate. People expect both occupied and unoccupied spaces to be cool in the event that
they might want to use a part of the building. This can be seen in the amount of thermal
zones within the building. Today, many residences have only one or two thermal control
zones while the Boroujerdi House had several, which allowed for a wider variety of
temperatures to occur and made certain parts of the house unusable for parts of the day or
parts of the year. This is a realistic attitude towards cooling buildings because there are
times of the day when a building doesn’t need to be cooled, such as a house when its
occupants aren’t home. If this attitude of not having a building cooled all day every day
were to be adopted today then cost savings and energy use savings would be greatly
increased.
Another way that the house utilized thermal mass was in the construction of a
basement.112 Basements are great ways of creating a cooler environment without
mechanical heating or cooling, because having a room surrounded by earth lowers the
room’s temperature to be within a few degrees of the earth’s temperature, which usually
undulated around 50°F. Such lowering of the room’s temperature can be significant
because the temperature of the earth tends to be far lower than the outside air temperature
due to its large amount of mass. This makes it a strong strategy to locate floors below
grade to cool them.
112 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185.
Courtyard
Another strategic use of space, in terms of cooling, was the creation of an internal
courtyard. The courtyard in the building is the center of the house through which
circulation, ventilation, daylight, and views are all realized.113 In terms of size, its
footprint is nearly as large as the building’s. The courtyard is open to the air and cuts
through both the first and second floor of the building. It is a critical design method
through which the house is kept cool due to the pool and plants inside, and the role that it
plays in the natural ventilation of the house. The interior of the courtyard has a shallow
pool along with trees and flowerbeds.114 The pool is used for passive cooling by way of
evaporative cooling which helps to create a microclimate inside the courtyard that is
several degrees cooler and more humid than the air outside the building. The plants also
contribute to the creation of the microclimate through shading, transpiration, and
evapotranspiration. The trees and plants shade some of the walls that line the courtyard,
thus reducing the thermal gain on those walls.115 This reduction in thermal gain goes a
long way towards aiding the building in keeping a cool interior. The second contributor
toward the courtyard microclimate is the fact that plants transpire. Transpiration causes
the plants to give off water vapor through pores in their leaves. This combined with the
moisture in the soil creates evapotranspiration which raises the courtyard’s humidity, and
thus makes it more comfortable in Kashan’s dry climate. When the evapotranspiration
from the vegetation and the evaporative cooling from the pool isn’t enough the cooling
113 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 114 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html. 115 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html.
effects can be sped up by turning on sprinklers over the pool. These are fed by an
underground cistern that collects rainwater for both drinking and for the sprinklers.116
Through the combined effect of the vegetation, the pool, and the sprinklers the courtyard
maintains a fairly cool microclimate during the warm and hot months of the year.
Wind Towers and Natural Ventilation
In addition to the courtyard, another defining feature of the house are the wind
towers. The wind towers were designed to capture the wind above the house and channel
it into the house to provide natural ventilation and cooling. The wind towers capture this
wind through their height and their shape. Because air moves faster higher off the ground
the wind towers are each 131 feet tall.117 This ensures that the wind towers have a good
chance at capturing wind, given that it is blowing that day. If the wind is blowing that day
then it has the possibility of coming from virtually any direction, as Kashan doesn’t have
a dominant wind from any direction.118 Because of this, two of the three wind towers are
eight sided, and one is four sided.119 This is means that no matter the wind’s direction it
can be captured.
116 Richard Hyde, ed., Bioclimatic Housing: Innovative Designs for Warm Climates (Sterling, VA: Earthscan, 2008), 182-185. 117 "Boroujerdi House," Historical Iranian, last modified November 12, 2010, accessed November 18, 2015, http://historicaliran.blogspot.com/2010/11/boroujerdi-house.html. 118 "Average Weather For Kashan, Iran," Weatherspark 119 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html.
Figure 22: Wind Towers and Roof Openings Source: Studio Integrate 2014
When the wind is captured and flows into the house it moves from south to
north120, the summer residence to the winter residence. It typically begins in the summer
residence because there are two wind towers and a dome, which also has openings on it,
which means that the summer residence has a higher capacity for bringing in cool air than
the southern part of the house. Once it enters the summer residence, it is channeled to the
courtyard where it passes over the pool and cools further. After passing over the pool it
flows into the northern part of the house to cool it.121
120 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html. 121 Ibid
Figure 23: Wind Flow Source: Studio Integrate 2014
The wind towers also have a secondary function apart from channeling air into the
house, which is to act as a chimney when there is no wind. The high ceilings and tall
towers, together create a natural stack effect where the hot air rises and exits through the
towers. In parts of the house that need cooling, but are further from the wind towers,
there are carefully oriented openings in the roof that allow the hot air to leave the room.
When the hot air is evacuated through the various openings in the roof, cooler air
from the ground level is brought in through the lower openings in the walls. This cycle of
convection creates a breeze through the house that lowers the internal temperature.122 The
towers and openings act as chimneys during the day, as well as at night, at which time
this process becomes night flushing due to the house’s thermal mass. Because of the
reversible nature of the wind towers the house has the capacity, in the warm months, to
always have air movement.
122 Studio Integrate, "Boroujerdi House," Studio Integrate Research, last modified 2014, accessed November 24, 2015, http://www.studiointegrate.com/brujerdiha_house.html.
Implications
The Boroujerdi House is an excellent example of designing a purely passive
house that utilizes a wide variety of methods which are climate and site specific. For the
most part the systems and methods used to cool the house are successful. The only
weaknesses in it are in the transferability of some of the techniques. The techniques that
are being referred to are the seasonal living and the outdoor sleeping. Many people in
western culture would object to not being able to use their building for parts of the year,
and to sleeping outside. However, this idea can be transferred in a different manner.
Today, when a building is not in use it is still being cooled. This is an incredible waste of
power because a house doesn’t need to be cooled if no one is home. This same attitude
can be applied to other buildings by dividing them into more thermal control zones and
not cooling parts of the building that are not in use. One of the strengths of the
Boroujerdi House is the courtyard. Courtyards are a great passive cooling technique
because they aid in natural ventilation. If a building includes a courtyard it becomes
much easier to get more parts of the building fresh air and to cool it because of its
conductivity to natural ventilation. Courtyards can also shade windows if arcades or other
similar structures are integrated. This eliminates having to size individual overhangs for
windows because the overhang, the arcade, shades the entire wall. This also provides a
cool and shaded place to walk and adds to the aesthetic appeal of the building. If the
interior of the courtyard is designed right it can create a microclimate that is cooler than
the surrounding macroclimate. This can be done by using a pool, a fountain, or any water
feature. A water feature brings in additional humidity which can increase the comfort of a
space that is situated in a hot and dry climate. Vegetation can also be a key element in
creating a microclimate. Many architects try to solve architecture problems with more
architecture when that may not be the best answer. Planting trees can be a cheaper and
simpler option in shading a wall or a window. Not only do trees and other vegetation
shade they also raise the overall humidity of a space because of evapotranspiration.
Strategically located water features and/or vegetation can create a cool microclimate that
shouldn’t be overlooked, because it can have a large impact on a building’s overall
comfort. The cool air can be brought into the building, or it can simply provide a cool
layer around some walls that aid them in lowering their heat gain. These benefits have
been widely used in many different buildings and should particularly by considered in
buildings in arid climates as that is where they have the highest potential for passive
cooling. In addition to the passive cooling benefits of courtyards they provide a great
opportunity for shaping the aesthetic of a building, bring in natural light, provide
additional circulation space, and can provide an opportunity to connect the building to
nature if they are landscaped.
The other great take-away from the Boroujerdi House is its use of wind towers.
Wind towers are geared more toward climates that have more wind and in which
additional air movement in the building would be beneficial, such as dry climates. This
means that they won’t work everywhere, however, where they are a viable strategy they
can make a perceptible impact on the interior temperature. The movement of air through
a space moves hot and stale air out of a space and, if designed correctly, can bring in
fresh, cooler air. Additionally, wind towers are valuable because they work in two
directions, with wind coming down them and air rising out of them through the stack
effect. Just like courtyards wind towers are visually powerful and can lend a lot to the
aesthetic of a building if desired. Both the technique of wind towers and courtyards
should be considered in Utah buildings, as well as other buildings in arid climates,
because they both provide great ways to circulate cool air through a building without help
from fans, pumps, or anything that uses electricity.
SALT LAKE VALLEY
The three case studies that have been analyzed showcase very well what can be
done for a building in terms of passive cooling, and they serve as great examples of what
has been done in climates similar to Utah. However, the Boroujerdi House and the NREL
RSF are located outside of Utah, which means that the techniques used can’t be copy and
pasted from them to a building in Utah. Passive cooling techniques in general can’t be
applied in a cookie-cutter manner because of their highly site specific nature, but the
closer the reference building is to the intended site of the building being designed the
better the techniques will translate. This can be seen in the use of wind and cooling
towers. These towers work best when they are located where wind will be consistently
present and where there is low humidity. The majority of Utah qualifies for the low
humidity criteria, but not all of Utah qualifies for the wind criteria. This is why when
referencing passively cooled buildings, like the NREL RSF and the Boroujerdi House, it
is important to also reference a building close to its intended site.
If a passively cooled building is to be built in Southern Utah then the Zion
Canyon Visitor Center is a very useful building to reference. If a passively cooled
building is to be built in the Salt Lake Valley and the surrounding areas, then it would be
desirable to have another building to reference that is closer than the Zion Canyon Visitor
Center. This is because while the conditions are similar between the Salt Lake Valley and
Southern Utah, there is still a noticeable difference, namely the latitude and the climate
zone. Salt Lake City and the surrounding area is located at 40.7°N123 and is categorized
123 "Coordinates For Salt Lake City, Utah," City Latitude Longitude, accessed April 10, 2016, http://citylatitudelongitude.com/UT/Salt_Lake_City.htm.
as climate zone 5 and climate zone 6.124 Springdale, the city that the Zion Canyon Visitor
Center is located in, is located at 37.2°N125 and is in climate zone 4.126 On a very basic
level this means that the sun angles in the two areas are different. On a deeper level this
means that the two parts of Utah experience heating and cooling differently. Southern
Utah has longer and hotter summers and a very mild winter because of its lower latitude
and different climate zone. The Salt Lake Valley, however, falls into the category of
climate zone 5. Climate zone 5 has slightly cooler summers than climate zone 4 does, and
its winters are colder. Some of the adjoining areas surrounding Salt Lake City are located
in climate zone 6, which has even cooler summers than climate zone 5, and its winters are
colder still. Areas in climate zone 6 still need cooling, but the time frame in which they
need it is much shorter. All of these climate zones qualify as areas that are hot and dry,
but it important to know that they experience this general climate type in different ways.
124 Norbert Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable Design Methods for Architects, 4th ed. (Hoboken, NJ: John Wiley & Sons, Inc., 2015), [102-103]. 125 "Coordinates For Springdale, Utah," City Latitude Longitude, accessed April 10, 2016, http://citylatitudelongitude.com/UT/Springdale.htm. 126 Norbert Lechner, "Chapter 5: Climate," in Heating, Cooling, Lighting: Sustainable Design Methods for Architects, 4th ed. (Hoboken, NJ: John Wiley & Sons, Inc., 2015), [102-103].
PARK CITY WINERY
Figure 24: Exterior Rendering of the Park City Winery Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
Figure 25: Site Plan for Park City Winery Source: Christian Bueno, Alexis Suggs, Jelaire Fluit
In order to provide a reference for the future integration of passive cooling in
buildings in the Salt Lake Valley, a hypothetical building will be presented and analyzed.
It is beneficial to use a hypothetical building because the ideas and techniques that have
been previously shown with the Zion Canyon Visitor Center, NRSL RSF, and the
Boroujerdi House can be synthesized into one building, which is located where the
majority of Utah’s population is located, in the Salt Lake Valley. The building that was
designed to synthesize these techniques is a medium sized winery with 32,511 square feet
of indoor space. It’s designed to be a commercial building that has a dual functionality of
producing wine and of serving as a social gathering space. It is located in Park City, Utah
which is a 30 minute drive west of Salt Lake City. Park City, located at roughly a 7,000
feet elevation, is categorized into climate zone 6, which means that it only requires
moderate cooling for four months of the year. While this is a fairly short amount of time,
the temperatures are still high with June having an average high of 75°F, July being 83°F,
August being 81°F, and September being 73°F. Additionally the month of May has both
heating and cooling needs as the average temperature is 65°F127, placing it at the balance
point between a heating month and a cooling month. The lower temperatures that Park
City experiences are a result of its higher altitude of 6,980 feet, whereas Salt Lake City’s
altitude is 2,715 feet lower at 4,265 feet. All of these factors come together to form a hot
and dry climate that is fairly mild in terms of cooling needs.
Passive Systems
Thermal Mass
One of the most prevalent trends in the design of wineries across the world, which
is also rooted in the traditional design of wineries throughout history, is the use of
127 "Climate Park City- Utah," table, US Climate Data, accessed April 11, 2016, http://www.usclimatedata.com/climate/park-city/utah/united-states/usut0390.
thermal mass for cooling parts of the winery, particularly the barrel caves. This approach
was adopted in the design of the Park City Winery because of its simplicity and
practicality. However, it was not uniformly implemented due to the nature of the
building. The building was designed to be a beacon in the middle of the city that would
attract locals and visitors to the bar, the event space, and to the building as a whole for
tours. This meant that the building needed to be above ground to a certain extent so as to
visually stand out. However, parts of the building could be sunk into the ground to
benefit from the thermal mass of the earth, since the building is located on a hilltop. This
elevated location allows for the building to be more visible, but it also means that it
cannot benefit from the possible shading of other buildings since the hilltop has no other
construction on it.
The building is composed of three floors stacked on each other vertically, each
housing a different type of social space and step of the production process. The first floor
contains the barrel showroom, barrel storage room, a private tasting room, a chiller, an
elevator, a grand staircase, restrooms, and emergency staircases. This floor in particular
needed to be kept between 50°F and 65°F at all times because it contains the barrels of
wine, which are sensitive to temperature and have higher rates of evaporation with higher
temperatures.128 The exterior walls are made of 12” thick concrete and they are
uninsulated because the whole space is underground and the cool temperatures of the
earth will condition it.
128 "Wine Barrel Humidification," chart, Miatech, accessed April 16, 2016, http://winery.miatech.org/cms.page.php?CPID=22.
Figure 26: Floorplan of Level 1 Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
The second floor contains entrances to the building, the lobby, a fermentation
room, two grand staircases, a bar, offices, a lab, a conference room, restrooms, and other
auxiliary spaces such as storage. The floorplan of this space is shaped like an “L” with
the lobby, fermentation tanks, and grand staircases in the longer north-south portion, and
the social spaces such as the bar along with the administrative spaces in the east-west
portion. Given that this floor is more social it was decided that it wouldn’t be completely
buried in the earth so that natural light could be utilized and views could be captured.
This resulted in completely burying the east side of the north-south segment and partially
burying the west side of the segment. This allows for the earth to insulate the space from
large fluctuations in temperature. The north, south, a small portion of the east and west
facades are left open to the site so that people can enter and exit the building as well as
have access to views, light, and natural ventilation. Additionally, this floor has 12” thick
exterior concrete walls, although it does not make up one hundred percent of the exterior
wall space.
Figure 27: Floorplan of Level 2 Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
Unlike the lower two floors the third floor does not utilize thermal mass very
much as it is intended to act like a light pavilion perched on top of a building that is
inserted into the hill. This is because the primary activities that happen on this floor are
event based and the idea of embracing the views more fully, allowing for natural
ventilation, and bringing in natural light to fill the space are very important. However, the
thermal mass that does exist is seen in the fact that all of the interior and exterior walls
that are solid are made from 12” thick concrete with the exception of the bathroom walls
which are 6” thick. This floor is not buried in the ground at all, but rather sits on top of
the hill so that it can act as a beacon.
Figure 28: Floorplan of Level 3 Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
Orientation and Windows
The Park City Winery has an incremental approach to glazing on its exterior
surfaces that begins with zero glass on the first floor and ends with more than 50% glass
coverage on the third floor. In terms of passive cooling, a 25% window-to-wall ratio is
highly desirable, and anything over that amount must be given a lot of attention in terms
of proper orientation and careful detailing to ensure that heat is rejected and that occupant
comfort is maintained. It is not suggested that buildings should have more than a 25%
window-to-wall ratio, rather it is discouraged, but in contemporary design many clients
want large amounts of glass for various of reasons. The Park City Winery has a lot of
glazing and will serve as an example of how to deal with varying amounts of glass should
the client or the program call for it.
On the Park City Winery most of the glazing faces south, and smaller amounts
face east and west. It was decided that the majority of the glazing would face south
because of the ease with which it could be shaded. On the second floor the glazing is seen
in the form of floor-to-ceiling curtain walls that frame the bar on the south, and west,
sides of the building. This glazing is designed to be shaded by the floorplate of the third
floor, which supports part of the event space above, as well as a balcony. The solar angles
were found for both the coldest part of the winter (26.3°N on January 1st) and the hottest
part of summer (72.3°N on July 1st)129 to determine what length of overhang would result
in the glazing being shaded in the summer, but admitted in the winter when the building
can benefit from passive heating. These calculations resulted in an overhang of 20 feet,
129 "Sunrise, Sunset, and Moon Times," Time and Date, accessed April 12, 2016, http://www.timeanddate.com/astronomy/usa/salt-lake-city.
which also shades the secondary entrance located on the south side of the building next to
the offices. Another set of glazing can be seen on the east side of the building in the form
of six windows that admit light into the three offices. It was decided that these windows
wouldn’t receive shading via an overhang because they don’t account for more than 25%
of the wall space and they would only contribute to heat gain in the early morning when
the sun’s heat has less of an impact. However, the windows were still given interior
shades to mitigate the little heat gain that they would incur.
Figure 29: Sectional Diagram of Overhangs and Sun Angles Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
The third floor of the building contains the highest amount of glazing with well
over 50% of exterior wall space being floor-to-ceiling glass curtain walls. The way that
this was addressed was through extending the flat roof to shade the glazing. The
overhang on the south side is sized at 29 feet past the main glass façade and 9 feet past
the lounge’s glass façade. The 9 foot overhang allows direct sun to enter in mid-
September, while the 29 foot overhang doesn’t allow direct sun into the event space until
early October. On the west and east side the overhang is 20 feet, which provides a small
amount of shading.
The crush pad, which also functions as a social space, has a lot of glazing on the
east and the west sides. Normally this would be an issue, but the space is designed to
function more as an enclosed pavilion than a sealed space. What this means is that the
glass walls are meant to be opened when the weather is warm, resulting in the heat
passing through the space rather than being trapped in it. If the weather isn’t pleasant
enough, the space isn’t used for events. The same mentality is used for the main event
space’s west face, which is also a curtain wall. This wall is meant to open up for natural
ventilation, but it would also be shaded by trees.
Even though the glazing is treated with extensive overhangs, the glass itself
couldn’t be ignored. If a window is not properly detailed then whatever was gained in
shading, could be lost through a poorly constructed window. In order retain what was
gained with strategic shading, all glass used meets the Passive House standard of being
triple pane and having a U-value of 0.14. The south facing windows on the second and
third floor would have a higher Solar Heat Gain Coefficient (SHGC) of 0.5 or better in
order to utilize winter solar heat gain, so that they are functional in both the summer and
winter.
Vegetation
It was decided that trees and shrubs would be used to shade the west windows
because they have the ability to grow tall enough to shade the third floor glazing, and
shrubs could be short enough to contribute to the shading of the second floor glazing. The
trees planted would be deciduous so they would shade in the summer, yet allow the sun
to enter the spaces and heat them in the winter. Not only would the vegetation shade the
glazing, it would also create a microclimate surrounding the west walls and add to the
cooling of the nearby space. Vegetation, rather than architectural elements such as fins,
was chosen to shade the west walls because they are cheaper than architectural elements,
they are naturally responsive to changing conditions, and they don’t have an impact on
the building’s aesthetics.
Figure 30: South Elevation Source: Christian Bueno, Alexis Suggs, Jelaire Fluit 2016
Natural Ventilation
One of the advantages of having such large amounts of glazing is that it opens up
the opportunity for extensive natural ventilation. The glazing is largely seen on the south-
west corner of the building, which is where the wind for this location predominantly
comes from. The wind in Park City technically comes from every direction, but the
strongest wind comes from the south-west and west directions and blows north-east and
east, respectively. By allowing for the glazing surrounding the second floor bar, third
floor event space, and third floor crush pad to be drawn back like a curtain it allows the
prevailing wind to come into the space and cool it. This would allow for the elimination
of additional mechanical summer cooling during the daytime because the combination of
thermal mass and night purging will keep the building below 78°F for the upper two
floors.
Performance
The Park City Winery was designed as a hypothetical building that could serve as
an example of how to design a passively cooled building in the Salt Lake Valley. It was
also given a hypothetical program and type of client. The client serves to embody the
contemporary trends of today’s market, namely the draw towards glass as an aesthetic
choice and as a way to capture views. The program was based on the idea of designing
for commercial and production needs, which in this case was a winery.
From an energy standpoint the Park City Winery is considered successful. This
can be seen in the fact that when the building was modeled with the software Sefaira, it
was shown to perform better than the 2030 Challenge. The 2030 Challenge, in short,
endeavors that “All new buildings, developments, and major renovations shall be carbon
neutral by 2030.”130 What this means is that “All new buildings, developments and major
renovations shall be designed to meet a fossil fuel, GHG-emitting, energy consumption
performance standard of 70% below the regional (or country) average/median for that
building type.”131 This would then be extended to 80% in 2020, 90% in 2025, and carbon
neutral by 2030. In order for the Park City Winery to meet that standard it would have to
have an annual energy usage of 24 kBtu/ft²/yr.132 However, when modeled with Sefaira it
130 "The 2030 Challenge," The 2030 Challenge, accessed April 13, 2016, http://architecture2030.org/2030_challenges/2030-challenge/. 131 Ibid 132 Ibid
was determined that the building would consume only 19 kBtu/ft²/yr. This puts it at 5
kBtu/ft²/yr better than the 2030 Challenge, and 61 kBtu/ft²/yr better than the national
average for commercial buildings, which is 80 kBtu/ft²/yr.133 While this doesn’t
determine if the building is successful in terms of passive cooling, it certainly indicates
that the building is doing something right in terms of energy as a whole.
Figure 31: Energy Use Per Square Foot and Percentages Source: EIA 2016
In focusing on just the energy needed to cool the building, it was determined that
the building would consume 79,946 kBtu/yr, which translates to $1,991.55 per year for
the entire building. The national average is 80 kBtu/ft²/yr for a commercial building, of
which 9% is the average amount spent on space cooling.134 This means that an average
commercial building with the same interior square footage of 32,511 square feet would
consume 234,079 kBtu/yr and would spend $5,831.17 per year on space cooling. This is a
77% reduction in energy consumption based on the average commercial building. The
benefits of such a reduction are major for the environment, as well as financially.
133 "Total Energy Used Per Square Foot In Commercial Buildings," chart, EIA, March 18, 2016, accessed April 13, 2016, https://www.eia.gov/consumption/commercial/reports/2012/energyusage/. 134 "Space Heating Demanded The Most Overall Energy Use In Commercial Buildings In 2012," chart, EIA, March 18, 2016, accessed April 13, 2016, https://www.eia.gov/consumption/commercial/reports/2012/energyusage/.
Additionally, there is a possibility of a further reduction in the cooling energy used
because Sefaira doesn’t account for the trees that would shade the west windows and the
earth tubes that would be used to precool the air used for the mechanical cooling systems.
Implications
The Park City Winery demonstrates that future buildings have the ability to
drastically reduce their cooling energy consumption, and their overall energy
consumption if they are designed thoughtfully. The Park City Winery doesn’t do
anything drastic in terms of building design which could impact the aesthetic of the
building in a negative way. It accommodates the program well and it works with its site
to provide a building that has significantly lower cooling energy needs. If architects look
at the techniques used in the Park City Winery then they can implement these strategies
in future building designs, resulting in buildings that reduce their impact on the
environment, have lower annual cooling costs, have good occupant comfort, respect their
site, and are aesthetically pleasing.
CONCLUSION
Architects
Passive cooling is a building technique that needs to be reclaimed by architects. It
gives the architect a deeper level of control over the design of the building by asking
them to get involved in how the building is cooled. Additionally, it forces them to think
more about the site and where the building is located; an architect cannot design a
building for passive cooling and not have a well-rounded understanding of the site and
the local climate. Passive cooling also forces the architect to think more about the people
who will be occupying the building because the occupants’ interaction with the building
can either enhance or detract from the success of the passive cooling systems, as is the
case with operable windows.
By becoming more involved in the overall design of the building, from the
aesthetics to the cooling systems, architects understand the building more fully and have
the ability to create a better design. If an architect only designs the aesthetics and the
spatial layout of a building then they don’t know the building intimately and they can’t
integrate everything as seamlessly. A sense of seamless integration where everything in
the building works harmoniously only happens when all of the systems are designed
together instead of by separate trades who hand off portions to each other without being
involved. The more seamless a building is the more successful it will be.
Not only does designing a building’s cooling systems in a passive manner bring a
greater sense of seamlessness to the building, it also is an opportunity to give more to the
client and to those who use and interact with the building over the course of its lifetime.
This is mainly done through operation costs and elevated design. When a design is
elevated because the architect has a better understanding of the building as a whole then
the client benefits. When the cost of cooling is lowered the client benefits.
Architects also have a social and ethic responsibility to the public and the
environment to create something that will enhance the world, not harm the world.
Buildings that ignore their context and consume energy as if there isn’t a price to pay for
it are parasites. Buildings that consider everything from how users interact and
experience the space to how it consumes energy and cools itself efficiently improve the
world. Endless consumption of energy is no longer an option if global warming is to be
slowed or stopped and if the destruction of the earth is to be stopped.
Tools for Passive Cooling
Architects have access to enormous amounts of information and reference sources
for all sorts of design challenges. With this ease of information access comes the ability
to see what other buildings have done in terms of passive cooling. Referencing other
buildings is one of the best tools that an architect has for beginning to integrate passive
cooling into their designs. This is why over the course of this paper three case studies and
one hypothetical building were presented. These buildings were analyzed so that
architects have more sources to draw from and can see that passive cooling is happening
and it is successful.
In conjunction with references architects also have another powerful tool that they
can utilize when they decide to design for passive cooling, energy modeling. A glimpse
of what energy modeling can help achieve was given in the section on the Park City
Winery. Energy modeling allows architects to see how their design decisions affect the
performance of the building before it is built. It also allows for architects to experiment
and test out different passive cooling techniques with no consequences since it is just a
digital model. When a good design solution has been discovered for a building energy
modeling allows the architect to show the client the implications that it has for energy
consumption and cost. This allows the architect to show with reliable information that
adding a feature such as overhangs is not just an aesthetic addition that costs the client
money, but rather that it is a passive cooling strategy that saves them money in
operational costs.
Passive Cooling for Utah
This paper has been focused largely on passive cooling strategies for Utah, and
other hot and dry climates, because of the large amounts of energy that buildings in these
climates consume via air conditioners. Hot climates in general, as opposed to more
moderate climates, have the most to gain from implementing passive cooling techniques.
If Utah were to adopt these practices, and architects that operate in the Salt Lake Valley
were to champion passive cooling then the energy reduction in the warm months would
be tremendous. Rocky Mountain Power, the main provider of energy to the Salt Lake
Valley, would feel less strain on their grid during the summer months, and there would be
less of a need to build any new power plants. A new power plant would help fulfill the
demand for cooling energy in the summer, but it would increase the cost of energy and it
would harm the environment. The cost of electricity is not declining but has been steadily
increasing over the years. This means that if a building is passively cooled than the cost
incurred every year would stay a lot more steady, especially if the building can achieve
100% passive cooling.
While 100% passive cooling for a building is desirable in terms of finances and
the environment, having all new construction and major renovations attempt to
incorporate passive cooling into their designs is the ultimate goal. This integration
doesn’t have to be complicated if it is implemented on a basic level. The hypothetical
Park City Winery doesn’t try to do anything fancy or complicated with its passive cooling
and it was able to meet, and exceed, the 2030 Challenge. This demonstrates that passive
cooling is very practical for Utah and for other hot and dry climates. Even simple things
like retrofitting buildings with operable windows and properly shading them would do
wonders for Utah’s energy consumption.
Having passive cooling integrated in more buildings would help to change the
mentality of endless consumption and would help shift people’s focus away from
ignoring a building’s context and toward seeing the impact that the building has.
Ultimately it’s the mentality towards consumption that needs to shift, then passive
cooling can begin to be the default designing mentality again with mechanical systems
being secondary as they should be.
AKNOWLEDGEMENTS
I would like to thank my parents for supporting me in writing this thesis and Jörg
Rügemer for mentoring me through this process.
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Name of Candidate: Alexis Suggs
Birth date: March 2, 1994
Birth place: Clinton Township, Michigan
Address: 765 E 400 S Salt Lake City, UT 84102