2019 IAQA Annual Meeting
Henry Slack
Slack Engineering
404-217-4229
Venting on Ventilation:
Is More Air Better for Us?
2019 IAQA Annual Meeting
Acknowledgements
• To Richard Shaughnesy and Terry Brennan, who taught me the basics;
• To Bill Fisk and the many other researchers whose work has been used in this presentation
2019 IAQA Annual Meeting
Air, Wonderful Air!
• ContentWe breathe 20-30 lbs air/day !
90% indoors – homes 70%, elsewhere 20%
Indoor air: chemicals, mold, bacteria, dust
May be high levels of radon, pesticides, odors, tobacco smoke, combustion gases
2019 IAQA Annual Meeting
?
• ContentCleans your air (usually)
Lowers levels of every pollutant (usually)
Health, productivity gain >> energy $
No conclusions, but data from research
2019 IAQA Annual Meeting
Pre-1940 or so
• Content
Stone, wood, metal materialsOpen windows whenever warm enoughOutdoor Air = Indoor AirLathe and plaster walls (high pH)Asbestos, lead-based paintNo central heat or A/C
2019 IAQA Annual Meeting
Since the 1950’s
• Content
Carpet, wallboardFinishes, glues,Computers, printers/copiers (toner)Cleaning chemicals, pesticidesCentral A/C and heat (and filters)We added chemicals & closed windows
2019 IAQA Annual Meeting
How Much Air?
• Content1890-1920: Ventilation engineers society (ASHVE) said 30 CFM per person
Levels were even put into state laws
After WWII, levels reduced based on odor studies, to 5-20 CFM/p
2019 IAQA Annual Meeting
1970’s Energy Crisis
• Content1973: ASHRAE Standard 62-73 recommended 7.5 CFM, set minimum of 5 CFM/p (non-smoking)
“Sick Building Syndrome” in the news
Std 62-89 recommended 20 CFM but set minimum to 15 CFM/p
2019 IAQA Annual Meeting
Currently
• Content
Complex formula; no single value, but
often 12-14 CFM/p
Separate standard for residential (62.2)
2019 IAQA Annual Meeting
Too Tight Homes?
• ContentASHRAE 62.2 recommends 0.3-0.35 ACH
Calif. Building Code: 0.35 ACH
Tight homes may be 0.02-0.20 ACH
Calif. study:70% < 0.35 ACH, high formaldehyde
Residential codes may not require ventilation
2019 IAQA Annual Meeting
High-Rises: Radon Gas!
• ContentRadon gas often 3-6x EPA “action level” (4 pCi/L) in concrete multi-family buildings
Why? Concrete can emit radon
Studied units measured as low as 0.02 ACH
FL: 30-40% of high-rise units > action level
Solved by adding ventilation (ERV)
2019 IAQA Annual Meeting
Green Building
Ventilation
• ContentBoth LEED (USGBC) and Green Globes require ASHRAE 62, plus source limits indoors (chemicals, tobacco smoke)
LEED also offers a credit in offices for 30% more outside air than ASHRAE 62
2019 IAQA Annual Meeting
Three Key Ideas from Research
• Content1) CO2 may be a pollutant in ways not previously recognized
2) Meta-analysis shows health benefits of more OA level off around 50 CFM/person
3) More ventilation would pay for itself in offices and schools
2019 IAQA Annual Meeting
• ContentWe all breathe out carbon dioxide (CO2)
Considered harmless to us, makes blood acidic
Outdoor air (OA) 400 parts per million (PPM) CO2
right now, but increasing
Office, schools: maybe 1,000-3,000 PPMSubmarines, Apollo 13: 10,000+ PPM
2019 IAQA Annual Meeting
CO2 and Decision-Making
• Content22 subjects completed tests of decision-making performance at 600, 1000, 2500 ppm CO2 , all same day, but in different order
Validated decision-making tests (SMS) results correlate with leadership skills Satish, U., et al. Enviro Health Perspect 120: 1671-1677
2019 IAQA Annual Meeting
Result
• ContentResult : statistically significant consistent downward trends on 7 of 9 decision scales
2019 IAQA Annual Meeting
More on CO2 Study
• ContentTests were double-blind: neither the subjects nor the technicians giving the tests knew what CO2 levels were present
Order of CO2 concentrations tested was varied to account for differences in subject’s level of alertness
2019 IAQA Annual Meeting
Is Our Children Learning?
• ContentMany school classrooms are over 1,000 ppm
TX study, 21% peak CO2 levels were >3,000 ppm
Office CO2 levels higher in meeting rooms, where decisions may be made
2019 IAQA Annual Meeting
Meta-analysis of
Ventilation Studies
• ContentReview of 27 separate studies shows health benefits from more OA delivery
Higher ventilation rates in offices are associated with reduced prevalence of Sick Building Syndrome symptoms (mostly respiratory).
The effect goes up to about 50 CFM/p (Sundell et al, Indoor Air 2011: 21; 191-204)
2019 IAQA Annual Meeting
More on Meta-analysis
• ContentConsistent across multiple investigations & different study designs for 6 different countries and populations
Suggests that lowering existing minimum ventilation rates inappropriate, but offered no support for any specific level of increase
2019 IAQA Annual Meeting
So, How much OA?
• ContentAuthors did NOT recommend any particular amount of outside air (but 50 CFM/p is 3-4x higher than ASHRAE Standard 62 recommends
They also didn’t discuss usingoutside air when local airpollution is bad
2019 IAQA Annual Meeting
Can Ventilation Pay?
• ContentMany studies: more ventilation leads to greater productivity in schools, offices1% increase in productivity pays $3-10,000/yr
Study of forty buildings found doubling ventilation saved 1.6 sick days (worth $500) per worker. Milton et al. (2000) Indoor Air Journal
2019 IAQA Annual Meeting
Can Ventilation Pay? - 2
• ContentWilliam Fisk at Lawence Berkeley Labs created national estimates
Doubling ventilation in U.S. offices yields productivity gains of $37 B (energy cost =$0.13 B).
Economizers that ventilate to save energy gain $33 B, but paying $0.28 B for equipment(Fisk, Building and Environment, 2011 )
2019 IAQA Annual Meeting
Great for Schools
• ContentSchools: increased ventilation improves school work & test scores 3-16%Wargocki and Wyon HVAC&R Research, 2007. 13(2): p. 193-220; Haverinen-Shaughnessy et al.Indoor Air, 2011. 21(2): 121-131; Murakami, S., et al., Proc. Healthy Buildings
2006. 2006. p. 271-276; Bako-Biro et al. Proceedings of Clima 2007
States pay for attendance; less absence = more $Fisk estimates $33 million from state (CA) for attendance but $6 mil added energy cost
2019 IAQA Annual Meeting
So, Ventilation…
• ContentVentilation improves IAQ, but takes energy, equipment
Pays off in office & schools
OA must be better than indoorsParticulates, ozone, wildfire smokeHumidity issues as well
2019 IAQA Annual Meeting
Ventilation Strategies
• ContentFrom Lawence Berkely Lab (NOT US EPA) http://www.iaqscience.lbl.gov/vent-practices.html
Design, operation, maintenance are key
Expert engineering judgments, not always fully proven by scientific research to provide health benefits
2019 IAQA Annual Meeting
Achieve Code/Standard
• ContentMaintain building ventilation rates at or above the minimum rates specified in current codes and standards
Periodic or continuous monitoring of OA intake flow rates, or indoor and outdoor CO2 levels, can assure ventilation actually delivered is consistent with design & operational intent
2019 IAQA Annual Meeting
Measure to Make Sure
• ContentOutdoor air intake design should allow reasonably accurate measurements of intake flow rates
Typical reliance on design (+ occasional air balancing) not recommended
Available data tells us building (and subspace) ventilation rates, in practice, are very often well below or above code requirements and professional standards
2019 IAQA Annual Meeting
Commissioning
• Content
• Commissioning, periodic re-
commissioning, and maintenance
are recommended
• Provide adequate access to air
handler components to enable
commissioning
2019 IAQA Annual Meeting
And If We Don’t?
• ContentCommonly reported ventilation equipment failures and control system problems, particularly in commercial buildings, point to the need for this ongoing commissioning & maintenance
2019 IAQA Annual Meeting
Survey the Occupants
• Content
• Post occupancy evaluations (POEs) are assessments, often surveys, to determine how well the building meets occupant needs
• A POE that assesses satisfaction with IAQ, for example with indoor odors, may provide indirect evidence regarding the adequacy of building ventilation
2019 IAQA Annual Meeting
Economizers
• Content
• OA economizers raise time-average
ventilation while saving energy
• Projected economic benefits of improved health
exceed, and add to, the energy cost savings
• During hot humid weather, controls may be
needed to keep them turned off
2019 IAQA Annual Meeting
ERVs!• Content
• Heat Recovery Ventilation (HRV) or Energy
Recovery Ventilation (ERV) systems reduce
ventilation-related energy use
• In some applications, HRV and ERV systems
should have a bypass to enable free-cooling
with OA when economically advantageous
2019 IAQA Annual Meeting
Painting/Cleaning/Waxing
• Content
• Increase ventilation rates for painting, cleaning,
waxing floors, etc., and perform when unoccupied
• Add exhaust ventilation or increase the existing rate
of mechanical exhaust ventilation from the area
• If exhaust ventilation impractical, increase ventilation
rate of space or building by adjusting OA
flow rates in existing mechanical ventilation
systems or by opening doors and windows
2019 IAQA Annual Meeting
Pollutant Source Control
• ContentReduce sources of indoor pollutants
Select low emitting building materials, consumable supplies
Change filters frequently
Increasing ventilation costs energy; pollutant source control usually doesn’t
2019 IAQA Annual Meeting
Disadvantages of More OA
• Content• Indoor concentrations of some outdoor air
pollutants can increase with ventilation rate
• When ozone is outdoors, increasing ventilation
rates will increase exposures to ozone
• May increase or decrease humidity, depending
on outside air water content
2019 IAQA Annual Meeting
Particles
• Content• More ventilation increases outdoor air
respirable particles (but reduce indoor-
generated particles)
• Higher outdoor particle concentrations
are associated with adverse health
effects
• Can lessen effects with good filtration
of OA
2019 IAQA Annual Meeting
Other Issues
• Content• If air is mixed well, do we need less
ventilation?
• Should ventilation systems be easily
adjustable by tenants? We set
thermostats– why not ventilation?
Or will we set too low?
Forget we shut it off?
2019 IAQA Annual Meeting
PM2.5 a special worry
• Content• One study found PM 2.5 had most health effects
(more than radon, secondhand smoke, formaldehyde)
• Affects cardiovascular (elderly) + unborn + babies
• “Citizen Science” (wearable monitors) coming
• When a customer’s building shows
high PM2.5, how will you respond?
2019 IAQA Annual Meeting
Conclusions
Air quality is vital to health
Research suggests more outside air ventilation would improve health and productivity, but at some cost of energy and equipment
Treat ASHRAE 62 as a minimum for good ventilation