passive design strategies in composite & warm-humid climates
TRANSCRIPT
PASSIVE SOLAR DESIGN FOR MUD HUTS IN
JHARKHAND, CONSIDERING
MICROCLIMATIC PARAMETERS FOR
COMFORT
JANMEJOY GUPTA
PHD/ARCH/1053/2011
DEPTT. OF ARCHITECTURE
GUIDE: DR MANJARI CHAKRABORTY
IMPACT OF CLIMATE ON DESIGN OF RURAL
DWELLINGS IN COMPOSITE CLIMATE &
WARM HUMID TYPE CLIMATE.
RURAL SETTLEMENTS IN RESPONSE TO THE
NATURAL ENVIRONMENT
Major natural features, such as mountains, rivers, lakes, forests, and grasslands, influenced both the location and organization of rural communities.
Climate, influenced the siting of buildings, construction materials, and the location of clusters of dwelling units.
Early settlements frequently depended upon available natural resources, such as water for transportation, irrigation.
Mineral or soil deposits, likewise, determined the suitability of a region for particular activities.
Locally available materials, such as stone or mud, commonly influenced the construction of houses.
Source: http://www.nps.gov/nr/publications/bulletins
IMPACT OF CLIMATE ON BUILT FORM : CONCEPT OF
BIOCLIMATIC ARCHITECTURE
Bioclimatic Architecture relates to the study of climate when
applied to Architecture, in order to improve the conditions of
thermal comfort of the occupants through the use of
appropriate building strategies, which differs from place to
place based on the prevailing climate of that place.
Source:
http://www.cres.gr/kape/energeia_politis/energeia_politis_bioclimatic_eng.htm
Centre for renewable energy sources and saving
PROCESS OF BUILDING CLIMATE-BALANCED
DWELLING UNIT
CLIMATIC DATA : TEMPERATURE,RELATIVE HUMIDITY,
RADIATION, WIND EFFECTS…
BIOLOGICAL EVALUATION: PLOTTING CLIMATIC DATA IN THE
BIOCLIMATIC CHART.
TECHNOLOGICAL SOLUTIONS
ARCHITECTURAL APPLICATION
CLIMATE DATA NEEDED FOR PASSIVE SOLAR
DESIGN
Climatic data collected in meteorological stations, and published in
summary form usually consists of:
Temperature: dry-bulb temperature.
Humidity: expressed as relative humidity or absolute humidity. Wet-bulb or dew-point temperatures may be stated, from which the relative humidity can be determined.
Air movement: wind speed and direction.
Precipitation: The total amount of rain, hail, snow or dew, in mm per unit time (day , month, year)
Cloud Cover: based on visual observation and expressed as a fraction of the sky hemisphere (tenths, or ‘octas’= eights) covered by clouds.
Sunshine duration: The period of clear sunshine (when a sharp shadow is cast), measured by a sunshine recorder which burns a trace on a paper strip, expressed as hours per day or month.
Solar radiation: measured by a pyranometer, on an unobstructed horizontal surface, usually recorded as the continuously varying irradiance (W/sq.meter)
THE FOUR ENVIRONMENTAL VARIABLES DIRECTLY
AFFECTING THERMAL COMFORT
The four environmental variables directly affecting thermal comfort are temperature, humidity, solar radiation and air movement.
The following data is of interest :
Temperature:
Monthly mean of daily maxima (degree Celsius)
Monthly mean of daily minima (degree Celsius)
Humidity:
Minimum Mean Relative Humidity (early morning) (in %)
Maximum Mean Relative Humidity (early afternoon) (in %)
Solar Radiation:
Monthly mean daily total (in MJ/sq meter or Wh/sq meter)
Sunshine: (percentage)
Wind: (prevailing wind speed in m/sec and direction)
Rainfall: (monthly total in mm)
AS PER NATIONAL BUILDING CODE, 2005
THE CLIMATIC ZONES IN INDIA IS-
1.HOT-DRY
2.WARM-HUMID
3.COMPOSITE
4.TEMPERATE
5.COLD
As can be seen from map the whole of
Jharkhand, except a small portion of it to the south,
falls within the composite zone of climate. Study-
Area Ranchi district falls entirely in composite zone.
Hot and dry summer,
followed by a humid
season with monsoon
rains. With the departure
of the monsoon it
gradually becomes
comfortable in autumn,
followed by a relatively
short winter (3 months)
with the cloudy and wet
as well as sunny periods.
Before the summer returns
there is a comfortable but
short spring season.
Source: www.mapsofindia.com
MAXIMUM AVERAGE TEMPERATURE FROM 1986-2013: RANCHI
MINIMUM AVERAGE TEMPERATURE FROM 1986-2013: RANCHI
MAXIMUM AVERAGE HUMIDITY FROM 1986-2013: RANCHI
MINIMUM AVERAGE HUMIDITY FROM 1986-2013: RANCHI
MAX & MIN TEMP: JAMSHEDPUR
HUMIDITY: JAMSHEDPUR REGION…WARM HUMID ZONE
BIOLOGY: COMFORT ZONE INDICATED IN BIOCLIMATIC CHART
FOR MEN AT SEDENTARY WORK IN WARM CLIMATES –
ORIGINALLY BY V OLGYAY IN BRITISH UNITS
Olgyay’s Bio-climatic chart Source: Koenigsberger,Ingersoll,Mayhew,Szokolay. Manual of tropical housing and building. Orient Longman. 1997.
OLGYAY’S BIOCLIMATIC CHART DESCRIBES THE
HUMAN-CLIMATE RELATIONSHIP TO ENSURE
COMFORT
A problem with Olgyay’s chart is that it does not account for differences between low mass and high mass buildings.
It assumes that the outdoor conditions, plotted on the graph, would be very close to the indoor conditions and can thus be used as guidelines for building design.
According to Bharuch Givoni this is only close to the truth in naturally ventilated lightweight buildings in temperate climates.
Source: La Roche, Pablo Miguel, 2004. Passive cooling strategies for
buildings in hot climates with specific application to Venezuela. Pro Quest Dissertations and Theses: The Sciences and Engineering Collection.
BUILDING BIO-CLIMATIC CHART (BBCC)
Givony (1969) developed the Building Bio-Climatic Chart (BBCC) to address the problems associated with Olgyay’s charts.
This chart is based on the temperatures inside buildings (expected on the basis of experience or calculations) instead of the outdoor temperatures. Givoni used the psychrometric chart to graphically represent the interrelation of air temperature and moisture content and is a basic design tool for building engineers and designers.
The BBCC suggests boundaries of the outdoor climatic conditions within which various building design strategies, as well as passive and low-energy cooling or heating systems can provide indoor comfort. (Givoni, 1994).
Source: La Roche, Pablo Miguel. Passive cooling strategies for buildings in hot climates
with specific application to Venezuela.
ProQuest Dissertations and Theses; 2004.
Revised Building Bio-Climatic Chart (BBCC) showing how building design strategies
causes adjustments in comfort zone. (generated in Climate Consultant Software).
Comfort zone in Ranchi’s Climate as indicated through Ecotect Simulation.
Comfort zone in Jamshedpur’s Climate as indicated through Ecotect
Simulation.
3. IMPACT OF CLIMATE ON RURAL BUILDING DESIGN :
TECHNOLOGICAL ASPECTS
SITE SELECTION
ORIENTATION
SHADING CALCULATIONS
HOUSING FORMS & BUILDING SHAPES
SIZE AND POSITION OF OPENINGS: WIND FLOW, DAYLIGHT AND SHADING
INDOOR TEMPERATURE BALANCE : CAREFUL USE OF MATERIALS FOR IMPROVED INDOOR CONDITIONS.
SETTLEMENT PATTERNS & SITE PLANNING
SUMMER OVERHEATED PERIOD & WINTER UNDER-
HEATED PERIOD
RADIATION GAIN IN COLD MONTHS &
AVOIDING RADIATION IN HOT
MONTHS: THE DIRECTIONS
PROBABLE ORIENTATION
Source: Victor Olgyay, Design with Climate: Bioclimatic Approach to Architectural
Regionalism, Van Nostrand Reinhold.
PREVAILING WINDS: SUMMER & WINTER
LESS HEAT GAIN IN SUMMER & MORE HEAT
GAIN IN WINTER-OPTIMUM :ORIENTATION
Optimum orientation
for least heat gain in
summer & maximum
heat gain in winter in
composite type of
climate prevalent in
Ranchi.
ADAPTING THE OPTIMUM ORIENTATION FOR
CAPTURING SUMMER TIME EARLY MORNING &
EVENING-BREEZE
TEMPERATURES INSIDE DWELLING UNIT IN
HOTTEST PERIOD OF YEAR..OPTIMUM
ORIENTATION..IN RANCHI DISTRICT
0 2 4 6 8 10 12 14 16 18 20 22
W/ m2C
-10 0.0k
0 0.4k
10 0.8k
20 1.2k
30 1.6k
40 2.0k
Outside Temp. Beam Solar Diffuse Solar Wind Speed Zone Temp. Selected Zone
NOTE: Values shown are environment temperatures, not air temperatures.
HOURLY TEMPERATURES - Zone 1 Tuesday 29th May (149) - Ranchi Jh IND, WMO#=ISHRAE
TEMPERATURES INSIDE DWELLING UNIT ON
HOTTEST DAY..OPTIMUM ORIENTATION..IN
EAST SINGHBHUM DISTRICT HOURLY TEMPERATURES - Tuesday 5th June
Zone: Zone 1
Avg. Temperature: 33.1 C (Ground 26.2 C)
HOUR INSIDE OUTSIDE TEMP.DIF
(C) (C) (C)
----- ------- -------- ---------
00 33.7 29.0 4.7
01 33.4 28.8 4.6
02 33.2 28.0 5.2
03 33.0 28.2 4.8
04 32.8 29.2 3.6
05 32.9 30.6 2.3
06 33.0 31.6 1.4
07 33.2 33.5 -0.3
08 33.3 34.5 -1.2
09 33.7 36.4 -2.7
10 33.8 37.8 -4.0
11 34.3 40.0 -5.7
12 34.4 40.9 -6.5
13 34.7 41.2 -6.5
14 34.6 39.3 -4.7
15 34.0 37.3 -3.3
16 33.3 34.6 -1.3
17 33.2 33.5 -0.3
18 33.3 32.4 0.9
19 33.5 32.5 1.0
20 33.6 31.7 1.9
21 33.7 31.5 2.2
22 33.9 30.4 3.5
23 33.8 30.3 3.5
POSSIBLE SHADING DEVICES
Fins
Chajjahs/sun-shades
Horizontal shading
devices
SHADING DEVICES
Krishan et al in ‘Shelter or Form’ in the compilation titled ‘Climate Responsive Architecture’-‘A Design Handbook for Energy Efficient Buildings’, states that in case of a composite climate, one would need to design shades that cut off the sun in summer but allow the sun in the under-heated period. Further, the window section should enhance air velocity while still acting as a shade. This could be achieved either by introducing a planter at the window sill or else by adding smaller shades at the glazing.
Source: Krishan, A., Jain,K. and Rajgopalan,M.,2001. Shelter or Form. In A.Krishan, N.Baker, S. Yannas & S. V. Szokolay (Eds.), Climate
responsive architecture: A design handbook for energy efficient buildings. New Delhi: Tata McGraw-Hill Publishing
Company Limited.
SHADING CALCULATIONS-STUDIED HOUSE
02
04
06
08
10
12
14
16
18
20
22
Hr
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Watts
600
480
360
240
120
0
-120
-240
-360
-480
-600
Indirect Solar Gains - Qs - Zone 1 Ranchi Jh IND, WMO#=ISHRAE
Indirect solar Gain:
South Zone
The above suggests that some form of temporary summer-time shading on the east side is
required, but something that doesn't adversely affect morning winter gains. Indirect solar gains
can be controlled by shading the east and west walls, or by using a white colour external finish on
facade.
02
04
06
08
10
12
14
16
18
20
22
Hr
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Watts
110
88
66
44
22
0
-22
-44
-66
-88
-110
Direct Solar Gains - Qg - Zone 1 Ranchi Jh IND, WMO#=ISHRAE
Direct solar Gain: South Zone
Probable ‘removable in winter’ shading options on east wall.
No shading on Southern walls needed. Only
shading of south void with sun shade is
required for protection during summer. South
wall void is contributing to winter time
heating.
HOUSING FORMS & BUILDING SHAPES
Source: The Energy and Resource Institute (TERI) guidelines, Solar Passive
Design for buildings, Page 7.
Of all geometrical shapes, the lowest surface-volume ratio is
that in case of a circular building.
The circular form of the building also enhances natural
ventilation inside the building.
The lesser the Surface-Volume Ratio of a dwelling unit lesser
is the heat gained by the building.
But since functionally, circular shape is not ideal, alternative
similar alternatives can be hexagonal or octagonal shaped
dwelling units.
PERIMETER TO AREA RATIO AND HEAT GAIN
Krishan et al (2001) in ‘Shelter or Form’ in the compilation titled ‘Climate Responsive Architecture’- ‘A Design Handbook for Energy Efficient Buildings’, states that in case of radiative gains or losses, the perimeter is a crucial factor. Greater the Perimeter to Area ratio (P/A), greater the radiative heat gain during the day and the greater the heat loss at night. Similarly, smaller the P/A ratio, the lesser will the heat gain be during the day and the lesser the loss at night. In hot climates the P/A ratio should be kept to a minimum to cause minimum heat gain.
HOUSING FORMS & BUILDING SHAPES
Cylindrical forms as seen in ‘Namboothiri House’ by Laurie Baker can be considered preferable solution in comparison to conventional forms.
Source: Induja, Chani PS, October 2013. Passive Strategies for Indoor Thermal Comfort in Warm and Humid Climate. Sustainable Architecture: Journal of The Indian Institute of Architects. Volume 78. Issue 10, Pgs 43-48.
www.lauriebaker.net
HOUSING FORMS & BUILDING SHAPES
Huts with roof openings for ventilation
A Traditional Courtyard House of the Coastal Area Made from Mudbricks (Barka, Al-Batinah)
Source: Abdul Majid, N.H., Shuichi,H. and Takagi, N., 2012. Vernacular wisdom: the basis of formulating compatible living environment in Oman, in: Proceedings of the ASIA Pacific International Conference on Environment-Behaviour Studies, Procedia-Social and Behavioral Sciences 68 (2012),Elsevier Science Direct, p. 637-648.
AIR MOVEMENTS: SIZE & POSITION OF OPENINGS
Well sealed windows and doors with maximum opening area
allow maximum exposure to cooling breezes and exclude hot,
dry and dusty winds.
An air speed of 0.5m per second equates to a 3 degree drop
in temperature at relative humidity of 50 per cent.
Night-time flushing out of heat is required for night time
cooling.
•Thermal currents are common in flatter, inland areas like Ranchi
created by diurnal heating and cooling. They are often of short
duration in early morning and evening but can yield worthwhile
cooling benefits with good design.
SIZE & POSITION OF OPENINGS:
VENTILATION
• Use of windows designed to deflect breezes from varying
angles. Locating windows on walls with best exposure to
common cooling breezes and design for effective cross flow of
air through the building.
• Directing airflow at levels suitable for the activity proposed
for the room.
Design to maximize beneficial cooling breezes by providing
multiple flow paths and minimizing potential barriers.
• Elevated structures can increase exposure to breezes.
• Include evaporative cooling and water features.
CONVECTIVE AIR MOVEMENT
Convective air movement relies on hot air rising and exiting at the highest point, drawing in cool air from shaded external areas over ponds or cool earth.
Convection produces air movement capable of cooling a building but has insufficient air speed to cool the occupants.
Solar chimneys can also be used to ensure effective convective air movement.
Clerestory windows, roof ventilators, and vented ridges, eaves and ceilings will allow heat to exit the building in nil breeze situations through convection.
COURTYARDS ARE SEEN IN MANY CONTEMPORARY HOUSES BUT THE SUCCESSFUL DEPLOYMENT OF
STACK EFFECT WHICH MADE THE TRADITIONAL COURTYARDS THERMALLY EFFICIENT IS ABSENT IN MOST
CASES. INSTEAD SOME SUCH COURTYARDS WITH POLYCARBONATE ROOFS ACT AS SMALL ISLANDS
TRAPPING SOLAR ENERGY AND INTENSIFYING THE HEAT INSIDE THE HOUSES. ATRIA OR LIGHT COURTS
PROVIDED IN CONTEMPORARY HOUSES TO INCREASE DAY LIGHTING CAN BE LINKED WITH A SYSTEM OF
EVAPORATIVE COOLING BY PROVIDING WATER SPRAYS AT THE TOP OR PROPER OPENINGS CAN BE
PROVIDED ON TOP TO EXPEL HOT AIR TO INITIATE STACK EFFECT.
Source: Fathy,H., Architecture for the Poor: An Experiment in Rural Egypt Chicago, 1973. Chicago. (The book was originally published in Cairo in 1969
under the title, Gourna: A Tale of Two Villages.)
Model rural house with pitched roof with vented monitor for
ventilation
Source: Typical Design of Rural Housing, Institute for Steel
development & Growth. August 2003, Page 20.
building is ventilated at night, its
structural mass is cooled by
convection from the inside,
bypassing the thermal resistance
of the envelope.
During the daytime the cooled
mass, can serve as a heat sink.
By radiation and natural
convection it can absorb the heat
penetrating into it.
Attainment of such performance
depends both on the – i. climatic
conditions and ii. on the design
details of the building.
Nocturnal ventilative cooling
INDOOR TEMPERATURE BALANCE: CAREFUL
USE OF MATERIALS
U: Thermal Transmittance : Is defined as the amount of heat in watts passing through 1 sq meter of a medium or a combination of media when a temperature difference of 1 Kelvin exists between the two sides.
Well-insulated parts of a building have a low thermal transmittance whereas poorly-insulated parts of a building have a high thermal transmittance.
The building material for the walls is mud and the roof material is Mangalore Tiles in a majority of huts. The U value for mud is 1.9 -2 .0 W/sq m K & the U value for Mangalore Tiles is 3.1 W/sq m K. (approx.)
Though U value of Mangalore/Clay Tiles and khapra used is not that high, the insulating property of thatch is much more, as its U value is even lesser. (0.35 W/sq m K) So in summer, it keeps the inside of the hut even cooler than clay tiles do. The disadvantages with thatch can be mitigated with modern day industrially improved hatch use.
Unit: Watt/Sq meter Kelvin.
HEAT CAPACITY
Heat capacity, or thermal capacity, is the measurable physical quantity of heat energy required to change the temperature of an object by a given amount. The SI unit of heat capacity is joule per kelvin. The term heat capacity of a wall or roof refers to the amount of heat required to elevate the temperature of a unit volume of the wall (volumetric heat capacity of material), or unit area of the surface (heat capacity of wall) by one degree.
INDOOR TEMPERATURE BALANCE: CAREFUL USE OF
MATERIALS
In the tropics the two important criteria for thermal design are the thermal resistance of a component and its thermal capacity.
Krishan et al (2001) suggests that in hot and cold climates the roof should have a low thermal transmittance value. Using insulation would minimize the heat stored by the roof. Further, in warm humid climates heat storage is undesirable. The roof should, therefore, be light, having low U-values and low heat capacities.
BETTER THERMAL PROPERTIES OF THATCHED ROOF AS
COMPARED TO CLAY TILED ROOF..BETTER THERMAL
COMFORT INSIDE. ACTUAL CASE. TOO HOT: 2700.0
TOO COLD : 1529.0
HOURS IN A YEAR (8760
HRS =365 DAYS)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hrs
00
160
160
320
320
480
480
640
640
Too Hot Too Cool
DISCOMFORT PERIOD - Circular Geometry Ranchi Jh IND, WMO#=ISHRAE
CLAY TILED HUT..SIMULATED CASE
TOO HOT: 3260.0
TOO COLD : 1307.0
HOURS IN A YEAR
(8760 HRS =365
DAYS)
Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
Hrs
00
160
160
320
320
480
480
640
640
Too Hot Too Cool
DISCOMFORT PERIOD - Circular Geometry Ranchi Jh IND, WMO#=ISHRAE
0 2 4 6 8 10 12 14 16 18 20 22
W/ m2C
-10 0.0k
0 0.4k
10 0.8k
20 1.2k
30 1.6k
40 2.0k
Outside Temp. Beam Solar Diffuse Solar Wind Speed Zone Temp. Selected Zone
NOTE: Values shown are environment temperatures, not air temperatures.
HOURLY TEMPERATURES - Circular Geometry Tuesday 29th May (149) - Ranchi Jh IND, WMO#=ISHRAE
INDOOR TEMPERATURE BALANCE: CAREFUL
USE OF MATERIALS
Modern day thatch treated and improved industrially can also be used for mass use in rural areas, being low cost and having very good thermal properties. Thatch is a natural reed and grass which, when properly cut, dried, and installed, forms a waterproof roof. The most durable thatching material is water reed which can last up to 60 years. A water reed thatched roof, 12 inches thick at a pitch angle of 45 degrees meets the most modern insulation standards. The U-value of a properly thatched roof is 0.35 W/sq m K, which is equivalent to 4 inches of fibreglass insulation between the joists. Only in the last decade have building codes begun to demand this level of roof insulation. Yet, thatch has been providing insulation since much longer.
Source: http://www.thatchco.com/thatchpg/
MODERN DAY THATCH TREATED AND IMPROVED
INDUSTRIALLY VERSUS TRADITIONAL THATCH
Source: http://www.thatchco.com/thatchpg/
Gautam Avinash. (2008). CLIMATE RESPONSIVE VERNACULAR ARCHITECTURE:
JHARKHAND, INDIA. Masters Level Thesis, Kansas State University.
DURABLE, FIRE RETARDANT THATCH ROOF
After prolonged research and development, studies and field trials, Central Building Research Institute (CBRI), Roorkee has developed a new method of making thatch roof fire retardant by manually pressing thatch panel and making it water repellent and durable by applying non-erodable mud plaster. The principal behind developing this new method and techniques of manually pressing lies that the basic cause of catching and spreading of fire is due to looseness of thatch grass in traditional type of roofing.
DURABLE, FIRE RETARDANT THATCH ROOF
Reduction of solar heat gain Composite Warm and Humid
Small surface-to-volume ratio Square plan, Low Wall Height Circular plan, Low Wall Height
Shading by neighbouring structures Clustering of houses, Courtyard
Shading by vegetation Deciduous trees
Shading by overhangs Overhanging roof
Openings Small openings
Reduction of heat transmission into
into interior
Thermal Insulation Insulating roof Insulating roof
Reduction of air infiltration/ventilation Moveable curtains/louvers/covers on
windows.
Increase of heat loss
Ventilation Courtyard effect, wind scoop. Courtyard effect, openings close to
roof, windows facing wind direction,
ventilation under raised floor,
ventilation through thin walls and
roof.
Evaporation Vegetation, sprinkling water
A
R
C
H
I
T
E
C
U
R
A
L
S
O
L
U
T
I
O
N
S (As per study by Bansal and Minke, 1988)
ARCHITECTURAL SOLUTIONS
• Thermal mass construction
• Wind towers
• Passive down draft evaporative cooling
systems
• Earth tunnel cooling
• Roofing systems
• Roof and wall insulation
THERMAL MASS CONSTRUCTION
A lot of heat energy is required to change the
temperature of high density materials like rammed earth. They are therefore said to have high thermal mass. Lightweight materials such as timber have low thermal mass.
During summer, it absorbs heat, keeping the house relatively cool.
In winter, the same thermal mass can store the heat from the sun to release it at night, helping the home stay warm.
Higher the density of the material, higher is the heat storage capability.
THERMAL MASS CONSTRUCTION
Thermal mass is most appropriate in climates with a large diurnal temperature range. As a rule of thumb, diurnal ranges of less than 6°C are insufficient, 7°C to 10°C can be useful depending on the climate; and where they exceed 10°C, high mass construction is desirable.
Correct use of thermal mass can delay heat flow through the building envelope by as much as 10 to 12 hours, producing a warmer house at night in winter and a cooler house during the day in summer.
WIND TOWERS
A typical View of Wind shaft, source:
www.catnaps.org/islamic/gulfarch.html
SOURCE: Eco-housing Assessment Criteria- Version II
Implemented under Eco-housing Mainstreaming Partnership by IIEC with funding support from
USAID
WIND CATCHER
DAY & NIGHT
Source: E. Hamzanlui Moghaddama, S. Amindeldarb, A.Besharatizadehb. New approach to natural
ventilation in public buildings inspired by Iranian’s traditional windcatcher. 2011 International Conference on
Green Buildings and Sustainable Cities. Procedia Engineering.
WIND TOWER
Evaporative Cooling, Source: Koenigsberger et al, 1997, Manual of tropical housing and
building: Climatic Design, Orient Longman.
WIND TOWER
R.Shanti Priya, M.C.Sundarraja, S.Radhakrishnan, L.Vijayalakshmi (2011). Solar passive techniques in
the vernacular buildings of coastal regions in Nagapattinam, Tamil Nadu,India-a qualitative and quantitative
analysis, Elsevier’s Science Direct, Energy and Buildings, Volume 49, Pages 54.
WIND TOWER
Source: H.P. Garg, R.L. Sawhney (1989). A case study of passive houses built for three climatic
conditions of India, Elsevier’s Science Direct, Solar & Wind Technology, Volume 6, Issue 4, Pages
401-418.
PASSIVE DOWN DRAFT EVAPORATIVE
COOLING SYSTEM (PDEC)
This system relies on the principle of
evaporative cooling. Large amounts of heat are consumed by water as it evaporates. This is called the latent heat of evaporation. This heat is partially drawn from the surrounding air, causing cooling.
The PDEC system consists of modified wind towers which guide outside breezes over a row of
water filled porous pots, mist spray or waterfall. As the air comes in contact with the water it cools
and descends down the tower and is let into the interior space. The water is collected in a pool
below and can be pumped up into the system to be reused.
Evaporative Cooling, Source: Koenigsberger et al, 1997, Manual of tropical housing and building:
Climatic Design, Orient Longman.
TECHNIQUES OF INCREASING MUD WALL
INSULATION :
By using loam mixed with additives : lightweight
straw loam for cob, adobe and rammed earth
walls.
Cavity walls with compressed earth block are also
effective.
Earth Covered roof Flat roof with loam in a Dogon village,
Shanga Mali
TECHNIQUES OF INCREASING ROOF INSULATION
Flat or inclined roofs with lightweight loam
on account of low thermal conductivity
Vault and domes on account of a lower surface volume ratio of roofing
Flat or inclined roofs with lightweight loam on account of low thermal conductivity
Source: Minke Gernot.(2006). Building with Earth: Design and Technology of a Sustainable Architecture, Birkhauser, Berlin.
Earth block vaults and domes
Vaulted roof building made of stabilized mud
blocks (composition: soil, sand, lime/cement
and water)
TECHNIQUES OF INCREASING ROOF INSULATION
Source: Minke Gernot.(2006). Building with Earth: Design and Technology of a Sustainable Architecture, Birkhauser, Berlin.
Persian dome with wind catchers
TECHNIQUES OF INCREASING ROOF INSULATION
Commonly used tile-covered rafter roofs can be filled with lightweight loam in order to increase their thermal and sound insulation.
If the space created by a typical 16-cm-high rafter is filled with lightweight loam with a density of 600 kg/m3 and the ceiling made of timber boards, the roof achieves an U-value of 0.8 W/m2K.
Three solutions, B, C and D, show possibilities for attaining higher levels of thermal insulation, as demanded in many countries.
ADVANTAGES OF VAULT AND DOMES ON ACCOUNT OF A
LOWER SURFACE VOLUME RATIO OF ROOFING
Vaults and domes covering interior spaces and made from earthen blocks are found mainly in religious buildings in Europe. In southern Europe, Asia and Africa, nonetheless, they have also been used in residences, offices and public buildings.
These structures demonstrate several advantages in hot and dry climates, especially in areas with a wide range of diurnal temperatures.
Given their inherent thermal mass and their greater heights at the centre of a space, where light, warm air gathers and can be easily discharged through openings, vaulted spaces provide better natural climatic control than standard cubic ones. They have smaller surface areas than cubic rooms of the same volume, and therefore less heat gain.
ADVANTAGES OF VAULT AND DOMES
In cold and moderate climates as well, vaults and domes have several advantages. As the surface area is smaller for the same volume, heat loss is lower, so heating energy is reduced.
In all climates, vaults and domes require less building material to enclose a given volume.
In all developing countries, vaults and domes are usually cheaper in comparison with flat or slightly inclined roofs.
Observation has shown that rooms with vaults and domes have a pleasing and calming effect on inhabitants in contrast to rooms with flat ceilings.
Until recently vaults and domes of loam have been built only with adobes.
ROOF INSULATION
Probable insulation using
gypsum/gyprock/glasswool in clay tiled pitched
roof.
Outside facade of traditional house, Yazd
Source: Hassan Fathy. Architecture for the Poor:
An Experiment in Rural Egypt (Chicago, 1973).
The book was originally published in Cairo in
1969 under the title, Gourna: A Tale of Two
Villages.
WALL INSULATION
Sanjay Kumar et al (1994) in ‘Amalgamation of traditional and modern cooling techniques in a passive solar house: A design analysis,’ talks about the different roof and wall designs/treatments that have been proposed, incorporating modern and ancient features for passive cooling.
Their research findings include:
different roof and wall designs/treatments have been proposed, incorporating modern and ancient features for passive cooling.
evaporative cooling with an air cavity in the roof is the best option to reduce the incoming heat flux through the roof if water is easily available.
a thin layer of cow dung slurry inside the wall cavity reduces the incoming heat flux through the walls. It is better than solid walls and air cavity walls.
Roof Material Figure
Straw thatch on pole timber on bamboo
substructure
Locally made country tiles on timber
substructure
Mangalore tiles on timber substructure
Wooden beams and boards covered with
straw and protective mud layer
Timber substructure carrying clay tiles
covered with mud
Composite Climatic Regions
- (As per study by Bansal and Minke, 1988)
Roof Material Figure
Straw thatch on pole timber on bamboo
substructure
Locally made country tiles on timber
substructure
Mangalore tiles on timber substructure
Warm Humid Climate regions
Wall Material Figure
Compacted earth rendered with cow dung
slurry
Stone masonry in mud mortar
Poles and twigs plastered with mud mortar
c. Summary of Identified Wall Construction Materials in the Composite (As per study by
Bansal and Minke, 1988) , Composite Climatic Regions
Wall Material Figure
Compacted earth rendered with cow
dung slurry
Woven bamboo matting without plaster
Warm Humid Climate regions
BIBLIOGRAPHY
http://www.nps.gov/nr/publications/bulletins.
http://www.cres.gr/kape/energeia_politis/energeia_politis_bioclimatic_eng.htm
Centre for renewable energy sources and saving.
Olgyay Victor (1963), Design With Climate- Bioclimatic Approach to Architectural
Regionalism, Van Nostrand Reinhold, New York.
Koenigsberger,Ingersoll,Mayhew,Szokolay. Manual of tropical housing and building.
Orient Longman. 1997.
La Roche, Pablo Miguel, 2004. Passive cooling strategies for buildings in hot
climates with specific application to Venezuela. Pro Quest Dissertations and
Theses: The Sciences and Engineering Collection.
The Energy and Resource Institute (TERI) guidelines, Solar Passive Design for
buildings, Page 7.
Induja, Chani PS, October 2013. Passive Strategies for Indoor Thermal Comfort in
Warm and Humid Climate. Sustainable Architecture: Journal of The Indian Institute
of Architects. Volume 78. Issue 10, Pgs 43-48.
Bansal,N.K. and Minke,G.,1988. Climatic zones and rural housing in India.
Zentralbibliothek Publishers, pp. 62-68, 132-149.
BIBLIOGRAPHY
Eco-housing Assessment Criteria- Version II Implemented under Eco-housing Mainstreaming Partnership by IIEC with funding support from USAID. E. Hamzanlui Moghaddama, S. Amindeldarb, A.Besharatizadehb. New approach to natural ventilation in public buildings inspired by Iranian’s traditional windcatcher. 2011 International Conference on Green Buildings and Sustainable Cities. Procedia Engineering.
http://www.thatchco.com/thatchpg/
Minke Gernot.(2006). Building with Earth: Design and Technology of a Sustainable Architecture, Birkhauser, Berlin.
Abdul Majid, N.H., Shuichi,H. and Takagi, N., 2012. Vernacular wisdom: the basis of formulating compatible living environment in Oman, in: Proceedings of the ASIA Pacific International Conference on Environment-Behaviour Studies, Procedia-Social and Behavioral Sciences 68 (2012),Elsevier Science Direct, p. 637-648.
Krishan, A., Jain,K. and Rajgopalan,M.,2001. Shelter or Form. In A.Krishan, N.Baker, S. Yannas & S. V. Szokolay (Eds.), Climate responsive architecture: A design handbook for energy efficient buildings. New Delhi: Tata McGraw-Hill Publishing Company Limited.
Fathy,H., Architecture for the Poor: An Experiment in Rural Egypt Chicago, 1973. Chicago. (The book was originally published in Cairo in 1969 under the title, Gourna: A Tale of Two Villages.)
http://www.eartharchitecture.com
THAT’S ALL
THANKS…