Presentation on theme: "Bringing the Outside In: Ventilation for Your Health Henry Slack U.S. Environmental Protection Agency Region 4."— Presentation transcript:
Bringing the Outside In: Ventilation for Your Health Henry Slack U.S. Environmental Protection Agency Region 4
Introduction to Air We breathe 20-30 lbs air/day ! 90% indoors – homes 70%, other bldgs 20% Indoor air: chemicals, mold, bacteria, dust Maybe high levels of radon, pesticides, tobacco smoke, combustion gases How can we improve out household air?
Ventilation! Cleans your air Lowers levels of every pollutant Health, productivity gain > energy $ Exploring ventilation, research Informational, but no firm conclusion U.S. EPA does not recommend ventilation quantities or delivery methods
How We Built Homes Long Ago Stone, wood, metal materials Open windows half of year Outdoor Air = Indoor Air Lathe and plaster walls (high pH) Asbestos and lead-based paint No central heat or A/C - unaffordable!
Homes for the past 50 years Carpets, wallboard, Particleboard Finishes, glues, foam insulation Computers, printers, copiers (toner) Cleaning, personal, pesticide chemicals Central A/C and heat, filters Yes- shut windows, added chemicals
Attached Garage Storing gasoline, paint, pesticide, other chemicals Autos (and if on, combustion gases) Water heaters, even furnaces No caulk or weather stripping between garage and kitchen = fumes come in
Ventilation Recommendations Florence Nightingale – 1860’s She + others: around 60 cubic feet of air per minute per person (CFM/p) Post-1973 energy crisis, the American Society of Heating Refrigerating, and Air-Conditioning Engineers (ASHRAE) recommended only 5 CFM/p in non- smoking offices
Ventilation 1980’s - now A few years later, ASHRAE raised their recommendation to 15 CFM/p. The present recommendation in office buildings is around 13 CFM/p, but the actual figure is calculated on the building size as well as occupancy, so it is not directly comparable. The U.S. EPA does not set ventilation standards.
ASHRAE Standard ASHRAE’s recommendations were originally made as Standard 62, “Ventilation for Acceptable Indoor Air Quality.” In 2005, this standard was split into 62.1 for most buildings and 62.2 for residential buildings Based on best science and “engineering judgment” so new science will change
LEED Leadership in Energy and Environmental Design (LEED) buildings could get extra credits for 30% more outside air than ASHRAE 62
Tight Homes ASHRAE 62.2 recommends 0.3-0.35 air changes per hour (ACH) Some new residences being built tighter without outside air ventilation Multi-family as low as 0.03 ACH Average across two studies: 0.10 ACH
Three Key Ideas CO2 may be a pollutant in ways not previously recognized Meta-analysis shows health benefits of more OA level off around 50 CFM/person More ventilation would pay for itself in offices and schools
Meta-analysis of Ventilation Studies Team of leading scientists reviewed 27 papers on health effects and ventilation written through 2005 Higher ventilation rates in offices, up to about 25 l/s/person [50 CFM] are associated with reduced prevalence of Sick Building Syndrome symptoms Sundell et al, Indoor Air 2011: 21; 191-204
How Much Outside Air Do We Need? 2011 Meta-analysis reviewed 27 separate studies shows health benefits from delivery of more outside air. 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)
50 CFM/person is 3x Current Rates! Consistency was found across multiple investigations and different epidemiologic designs for different populations Suggests that lowering existing minimum ventilation rates inappropriate, but offered no support for any specific level of increase
More on the Meta-Analysis Consistent across multiple investigations, different countries, different research designs, so strong. 50 CFM/p is 3-4x higher than ASHRAE Standard 62 recommends. This study did NOT recommend any particular amount of outside air They also didn’t discuss using outside air when local air pollution is bad.
CO2 We all breathe out carbon dioxide (CO 2 ) CO2 levels may affect our ability to make decisions. Typical levels have been viewed as harmless, although more CO 2 makes our blood more acidic. Outdoor air has around 400 parts per million (PPM) CO 2 right now. A typical office building may see levels go up to 1,000 PPM (or 0.1%) during the day as occupants breathe out. Buildings without ventilation may go much higher, and submarines and space capsules may be 10,000 PPM or more
More on CO2 Outdoor air has around 400 parts per million (PPM) CO 2 right now. Offices may go up to 1,000 PPM (or 0.1%) during the day Buildings without ventilation may go much higher Submarines and space capsules may be 10,000 PPM or more
Decision Making Tests Decision-making tests correlate with leadership skills. Reliable: Tested on thousands of people 22 subjects took tests. Same people, same room, same day, but the air held different levels of carbon dioxide (CO 2 ) each time: 600 PPM, 1,000 PPM, and 2,500 PPM
CO2 and Decision-making 22 subjects completed tests of decision- making performance at 600, 1000, 2500 ppm CO2, all the same day, but in different order Validated decision-making tests (SMS) Satish, U., et al. Enviro Health Perspect 120: 1671-1677
Result Result : statistically significant consistent downward trends on 7 of 9 decision scales
Slides Tests were double-blind: neither the subjects nor the technicians giving the tests knew what CO 2 levels were present. They even changed the order of the CO 2 concentrations tested, so that the subject’s level of alertness would not be a factor.
Is Our Children Learning? Many school classrooms are over 1,000 ppm; in TX, 21% peak CO2 levels were >3,000 ppm Office CO2 levels may be higher in meeting rooms, where decisions are made
Does it Pay? Many studies: more ventilation leads to greater productivity in schools, offices 1% increase in vent: $3-10,000/year Doubling ventilation yields productivity gains of $37 B (energy cost =$0.13 B). Economizers gain $33 B, saving energy but paying $0.28 B for equipment. (Fisk, Building and Environment, 2011 )
So What About Ventilation? Ventilation air can solve or improve almost any indoor air problem, Cost: equipment and energy Outdoor air must be better than indoors Particulates, ozone concerns
Humidity an Issue Moisture from ventilation may change indoor moisture levels and comfort Mold grows with moisture, too. Brand new southern coastal school added outside air without moisture control. School closed within a year to dry and clean
Bringing The Outside In Our Homes Deliver outside air in and push out IA Exhaust inside air and draw in OA Balanced methods do both No single choice
Exhaust –Only Fans In most bathrooms, many kitchens Reasonable price, but… Where does make-up air come from? –May draw in radon, mold, garage fumes –May bring in high-humidity air, grow mold –Does this air go to every room?
Exhaust-only House Shows fans on, bringing in outside air
Supply-Only Air source is known, air delivered into HVAC system to filter, dehumidify, change temperature Pushes some air out, no problem. More expensive, for equipment and for energy to treat the air More complicated
Supply-Only: CARB Study Measured chemicals in newer homes Homes had no OA system, supply-only system, or balanced systems None of the 8 supply only systems was working properly Chemical levels in these homes mirrored homes with no ventilation.
Supply-only House Shows fans on, bringing in outside air
Balanced ventilation systems Exhaust indoor air, deliver outdoor air Heat exchangers transfer heat, save $ –Heat Recovery Ventilator (HRV) – heat only –Energy Recovery Ventilator (ERV) – heat and moisture, humid climates More $ CA : ERV homes= lower chemicals
ERV/HRV House Shows fans on, bringing in outside air
Maintenance HVAC requires maintenance. Recommended 2x/year Not always done, and not done on ventilation equipment
Filtration Filtration –needed on outside air intakes? San Francisco Code 38 requires that outside air delivered to residences near freeways (which have high PM) must use a high grade of filter (MERV 13) to remove some of the PM.
Other Issues If air is mixed well, less ventilation? –Experts on both sides Adjustable system? We set temperatures up and down – why not ventilation? Will we set too low?
Conclusion Air quality is crucial to breath and health Research suggests greater outside air ventilation would reduce chronic disease “Best” system depends on location and equipment maintenance U.S. EPA does not recommend ventilation quantities or delivery methods