venting on ventilation: is more air better for us?

2019 IAQA Annual Meeting

Henry Slack

Slack Engineering

[email protected]

404-217-4229

Venting on Ventilation:

Is More Air Better for Us?


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


Ventilation:

What Is It Good For?

• Content


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


?

• ContentCleans your air (usually)

Lowers levels of every pollutant (usually)

Health, productivity gain >> energy $

No conclusions, but data from research


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


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


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


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


Currently

• Content

Complex formula; no single value, but

often 12-14 CFM/p

Separate standard for residential (62.2)


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


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)


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


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


• 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


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


Result

• ContentResult : statistically significant consistent downward trends on 7 of 9 decision scales


• Content


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


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


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)


Why 50 CFM/person?

• Content


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


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


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


• Content


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 )


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


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


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

http://www.iaqscience.lbl.gov/vent-practices.html


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


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


Commissioning

• Content

• Commissioning, periodic re-

commissioning, and maintenance

are recommended

• Provide adequate access to air

handler components to enable

commissioning


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


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


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


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


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


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


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


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


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?


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?


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


Questions?

Henry Slack

[email protected]

venting on ventilation: is more air better for us?

Documents