1 Building Dynamics and Weatherization Leif Albertson University of Alaska Fairbanks Bethel, Alaska

2 Overview The house as a system The house as a system Purpose of houses Purpose of houses Systems in a house Systems in a house Heating, cooling, ventilation Heating, cooling, ventilation Building Science overview Building Science overview Heat, moisture Heat, moisture What is weatherization? What is weatherization? How can weatherization affect health? How can weatherization affect health?

3 The House as a Dynamic System

4 Enclosures Shelter Us From Animals and insects Animals and insects Wind Wind Sun Sun Rain (sleet, snow) Rain (sleet, snow) Cold or hot air Cold or hot air Dust Dust

5 Whats a house?

6 Phoenix San Francisco Seattle Anchorage Honolulu Billings Saint Paul Wichita Houston Cleveland Boston Denver DC Atlanta Miami Tulsa Marquette Bangor Saint John Salt Lake Nashville Los Angeles New Orleans Saint Louis

7 Kotzebue Nome Sitka Fairbanks Bethel Barrow Phoenix San Francisco Seattle Anchorage Honolulu Billings Saint Paul Wichita Houston Cleveland Boston Denver DC Atlanta Miami Tulsa Marquette Bangor Saint John Salt Lake Nashville Los Angeles New Orleans St. Louis

8 Parameters of Comfort Air temperature: 65° F (active) – 80° F (bathing) Air temperature: 65° F (active) – 80° F (bathing) Air relative humidity: 30% – 70% Air relative humidity: 30% – 70% Air motion: 20 – 40 feet per minute Air motion: 20 – 40 feet per minute Surrounding surface temperatures: within 10 – 15° F of room air Surrounding surface temperatures: within 10 – 15° F of room air

9 We have systems to… Add heat Remove heat Ventilate Maybe add or remove humidity

10 Heating Systems Fuel – gas, oil, wood, electric Fuel – gas, oil, wood, electric Distribution Distribution hot water, steam, warm air, space heaters hot water, steam, warm air, space heaters Radiators, baseboard, ducts Radiators, baseboard, ducts Radiant floors and ceilings Radiant floors and ceilings Solar Gains Solar Gains Internal Gains (people, pets, appliances) Internal Gains (people, pets, appliances) Controls – thermostat, manual Controls – thermostat, manual

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12 Heating Systems Alaskan

13 Cooling Systems Fuel – electric Fuel – electric Windows, fans and shades Windows, fans and shades Distribution Distribution Central air Central air Through the wall Through the wall Duct-less splits Duct-less splits Dehumidification Dehumidification Air conditioners/part-load Air conditioners/part-load Dehumidifiers Dehumidifiers Control – thermostat, humidity Control – thermostat, humidity

14 Passive Ventilation: Stack Effect

15 Active Ventilation Local exhaust (unbalanced or balanced) Local exhaust (unbalanced or balanced)

16 Heat Recovery Ventilation Example of balanced ventilation Example of balanced ventilation Energy efficient Energy efficient Require maintenance Require maintenance

17 Moisture Cold air holds less moisture than warm air. Cold air holds less moisture than warm air. Relative humidity is what matters If relative humidity is too high, liquid water can form (dew point) Heating air makes it drier

18 Stack Effect, Condensation

19 Vapor Barrier Prevents air leakage and moisture inside walls Prevents air leakage and moisture inside walls

20 Top 10 Building Science Concepts 1. Heat flows from hot to cold 1. Heat flows from hot to cold 2. Heat does not risewarm air rises 2. Heat does not risewarm air rises 3. Heat is transferred by conduction, convection, radiation 3. Heat is transferred by conduction, convection, radiation 4. Heat flow through insulation is slowed by trapped air or other gases 4. Heat flow through insulation is slowed by trapped air or other gases 5. Air-tightness prevents major heat loss 5. Air-tightness prevents major heat loss

21 Top 10 Building Science Concepts (cont.) 6. Air flows from higher pressure to lower pressure 7. Air leakage is primary moisture transport mechanism 8. Diffusion is secondary moisture transport mechanism 9. Dew point is temperature at which airborne water vapor condenses into liquid water. Water vapor is not a problem, liquid water is 10. Vapor retarder should be placed on warm side of thermal envelope

22 Weatherization The practice of The practice of Protecting a building and its interior from elements Protecting a building and its interior from elements Modifying a building to reduce energy consumption and optimize energy efficiency Modifying a building to reduce energy consumption and optimize energy efficiency What kinds of things do we focus on? What kinds of things do we focus on? Sealing air leaks, adding insulation, replacing windows, new siding, etc… Sealing air leaks, adding insulation, replacing windows, new siding, etc…

23 Dennis Chart

24 Sealing Leaks Air leaks are greatest source of heat loss in most homes Air leaks are greatest source of heat loss in most homes

25 What about fresh air? At least 15 cubic feet/minute (cfm) for a healthy, non-smoking home *ASHRAE At least 15 cubic feet/minute (cfm) for a healthy, non-smoking home *ASHRAE Where does this air come from? Where does this air come from?

26 Can Weatherization Affect Health? Can make house warmer, less drafty Can make house warmer, less drafty Heat Recovery Ventilators can filter air from outdoors Heat Recovery Ventilators can filter air from outdoors Can reduce amount of fresh air in home Can reduce amount of fresh air in home Construction (and destruction) can produce dust, VOCs, disturb mold spores, etc. Construction (and destruction) can produce dust, VOCs, disturb mold spores, etc. Can a house be too tight? Can a house be too tight?

27 Why Do We Need Outside Air? Indoor air is usually worse for you Indoor air is usually worse for you Humidity can be too high or too low Humidity can be too high or too low Mold, bacteria, dry lungs Mold, bacteria, dry lungs Products of combustion Products of combustion CO, CO 2, NO X, other CO, CO 2, NO X, other Soot from boiler or woodstove Soot from boiler or woodstove Dust, pet dander, pest wastes, etc Dust, pet dander, pest wastes, etc Odors Odors Pathogens (germs) Pathogens (germs)

28 What happens when we reduce ventilation? Unhealthy levels of gases and particulates can build up Unhealthy levels of gases and particulates can build up In schools and offices, performance decreases, absenteeism increases In schools and offices, performance decreases, absenteeism increases Healthy people develop respiratory problems Healthy people develop respiratory problems Existing respiratory problems are exacerbated Existing respiratory problems are exacerbated Air can smell bad Air can smell bad Air can become too humid (damp) Air can become too humid (damp)

29 What to do? Tightening buildings is good for energy, but can be bad for health Tightening buildings is good for energy, but can be bad for health

30 Build it Tight, Ventilate it Right Be aware of health implications of tightening houses Be aware of health implications of tightening houses Modern ventilation systems (HRVs) can enhance human health while conserving heat Modern ventilation systems (HRVs) can enhance human health while conserving heat Traditional ventilation (bathroom fan, range hood, windows) valuable if used correctly Traditional ventilation (bathroom fan, range hood, windows) valuable if used correctly Education of residents paramount Education of residents paramount

31QuyanaQuestions? Leif Albertson Bethel, Alaska (907)