Indoor Air Quality

1. Indoor Air Quality WEATHERIZATION ENERGY AUDITOR SINGLE FAMILY WEATHERIZATION ASSISTANCE PROGRAM STANDARDIZED CURRICULUM – August 2010

2. Learning Objectives Indoor air quality • By attending this session participants will: • Learn about the factors effecting IAQ. • Understand the role moisture plays in IAQ. • Learn about moisture movement. • Learn pollutant remediation techniques. • Understand the requirements of ASHRAE 62.1989 and ASHRAE 62.2 2007.

3. IAQ, Moisture and Ventilation Indoor air quality • Moisture • Stored Toxic Materials • Carbon Monoxide (CO) • Radon • Sewer Gas • Other Photo courtesy of The US Department of Energy

4. Sources of Water Vapor Indoor air quality

5. Moisture Movement Indoor air quality Air flow Air molecules are blocked. Both water vapor and air molecules pass through. Water vapor molecules are passed. Diffusion Through Surface Convection Through Holes

6. Permeance of Building Materials Indoor air quality Permeance of Building Materials Material placed on the warm side of a building surface to retard diffusion of water vapor is called a vapor barrier. Material intended to retard convection is called an air barrier. Material which accomplishes both is termed an air/vapor barrier. A material qualifies as a vapor barrier if its permeance is 1.0 perm of less.

7. What Determines IAQ? Indoor air quality Photos courtesy of The US Department of Energy

8. Pollutant Action Tree Indoor air quality • Source • Eliminate • Encapsulate • Dilute • Driver • Eliminate • Weaken • Path • Eliminate • Block Photo courtesy of The US Department of Energy

9. IAQ and Relative Humidity Indoor air quality Relative Humidity and Indoor Air Quality Relationships Decrease in bar width indicates decrease in effect

10. Outside Air and IAQ Indoor air quality How much outside air do we need for good IAQ? How do we get it? WIND DIRECTION Exhaust Fan Wind Buoyancy Stack effect - warm air rising Mechanical Fans

11. How is Natural Ventilation Calculated? Indoor air quality WIND DIRECTION positive pressure positive pressure negative pressure negative pressure

12. Building Tightness Limit, Building Tightness Limit “a”, & Minimum Ventilation Guidelines Indoor air quality Photos courtesy of The US Department of Energy

13. MVG Theory Indoor air quality The amount of air leakage across any barrier is dependent on: • Hole size • Hole type • The pressure differential • Long/narrow vs.big/round • Thick vs. thin surface • “Hairy” vs. smooth bore Resulting in turbulent flow vs. linear flow vs. “drag”/friction

14. Random Hole Type? Indoor air quality Photos courtesy of The US Department of Energy

15. Random Size & Distribution? Indoor air quality Neutral pressure plane

16. What’s Left? Indoor air quality Tiny, deep bore, crack type holes through multiple layers located where wind and stack effect are minimal.

17. ASHRAE 62.1989 Indoor air quality Photos courtesy of The US Department of Energy

18. ASHRAE 62.2-2007 Indoor air quality Photos courtesy of The US Department of Energy

19. ASHRAE 62.2-2007 Table Indoor air quality Table 4.1a: Minimum Ventilation Air Requirements, CFM, New Buildings1 45 1 R.J. Karg of R.J. Karg, Associates

20. ASHRAE 62.2-2007 Formula Indoor air quality New or Existing Buildings2: • Assumes two occupants in master bedroom and one in the other bedrooms. Over this density, increase ventilation by 7.5 cfm/person. • Whole building, intermittently operating ventilation may be used under some conditions for compliance. • Ventilation air must come directly from the outdoors. • Credit is allowed for envelope air leakage in some cases, based on ASHRAE 62.2 and 136. Qfan = 0.01Afloor+ 7.5(Nbedroom+ 1) A = conditioned floor area; “the part of the building that is capable of being thermally conditioned for the comfort of occupants.” (ASHRAE 62.2, p.3) 2 R.J. Karg of R.J. Karg, Associates

21. What are Auditor’s Choices? Indoor air quality • Use ASHRAE 62.2-2007. • When using ASHRAE 62.1989: • Install the MVG recommended fan capacity. • Use client education on running fans for moisture control/mitigation to establish fan run time.

22. Installing Fans Indoor air quality Photo courtesy of The US Department of Energy

23. Upgrading ASHRAE 62.1 Installations to 62.2 Indoor air quality • Measure fan flow • Install Fan Control

24. Air-to-Air Heat Exchanger Indoor air quality Photo courtesy of The US Department of Energy

25. Summary Indoor air quality • IAQ depends on the pollutant source strength and the air change rate. Elimination at the source is preferable to confinement, which is preferable to dilution. • Many pollutants are present in the average home: The air change rate is a function of inside to outside pressure difference, hole size, and hole location. • A higher air change rate equals better IAQ, and usually higher space conditioning costs. • ASHRAE 62.1 and 62.2-(2004 or 2007) guidelines are acceptable. • Quality fans installed and used properly help ensure healthy IAQ.