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Building Building Dynamics and Dynamics and WeatherizationWeatherization

Leif AlbertsonLeif Albertson

University of Alaska University of Alaska FairbanksFairbanks

Bethel, AlaskaBethel, Alaska

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OverviewOverview

The house as a systemThe house as a system Purpose of housesPurpose of houses Systems in a houseSystems in a house

Heating, cooling, ventilationHeating, cooling, ventilation Building Science overviewBuilding Science overview

Heat, moistureHeat, moisture

What is weatherization?What is weatherization? How can weatherization affect health?How can weatherization affect health?

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The House as a Dynamic The House as a Dynamic SystemSystem

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Enclosures Shelter Us FromEnclosures Shelter Us From

Animals and insectsAnimals and insects WindWind SunSun Rain (sleet, snow)Rain (sleet, snow) Cold or hot airCold or hot air DustDust

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What’s a house?What’s a house?

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Phoenix

San Francisco

Seattle

Anchorage

Honolulu

Billings Saint Paul

Wichita

Houston

Cleveland

Boston

Denver DC

Atlanta

MiamiTulsa

MarquetteBangor

Saint John

Salt Lake

Nashville

Los Angeles

New Orleans

Saint Louis

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KotzebueNome

Sitka

Fairbanks

Bethel

Barrow

Phoenix

San Francisco

Seattle

Anchorage Billings Saint Paul

Wichita

Cleveland

Boston

Denver

DCAtlanta

Tulsa

Marquette Bangor

Salt Lake

Nashville

Los Angeles

New Orleans

St. Louis

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Parameters of ComfortParameters of Comfort Air temperature: 65° F (active) – 80° Air temperature: 65° F (active) – 80°

F (bathing)F (bathing) Air relative humidity: 30% – 70%Air relative humidity: 30% – 70% Air motion: 20 – 40 feet per minuteAir motion: 20 – 40 feet per minute Surrounding surface temperatures: Surrounding surface temperatures:

within 10 – 15° F of room within 10 – 15° F of room airair

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We have systems to…We have systems to…

Add heat Remove heat Ventilate Maybe add or remove humidity

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Heating SystemsHeating Systems

Fuel – gas, oil, wood, electricFuel – gas, oil, wood, electric DistributionDistribution

hot water, steam, warm air, space heatershot water, steam, warm air, space heaters Radiators, baseboard, ductsRadiators, baseboard, ducts Radiant floors and ceilingsRadiant floors and ceilings

Solar GainsSolar Gains Internal Gains (people, pets, Internal Gains (people, pets,

appliances)appliances) Controls – thermostat, manualControls – thermostat, manual

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Heating SystemsAlaskan

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Cooling SystemsCooling Systems Fuel – electricFuel – electric Windows, fans and shadesWindows, fans and shades Distribution Distribution

Central airCentral air Through the wallThrough the wall Duct-less splitsDuct-less splits

DehumidificationDehumidification Air conditioners/part-loadAir conditioners/part-load DehumidifiersDehumidifiers

Control – thermostat, humidityControl – thermostat, humidity

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Passive Ventilation: Passive Ventilation: Stack EffectStack Effect

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Active VentilationActive Ventilation

Local exhaust Local exhaust (unbalanced or (unbalanced or balanced)balanced)

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Heat Recovery Heat Recovery VentilationVentilation

Example of Example of “balanced “balanced ventilation”ventilation”

Energy efficientEnergy efficient Require Require

maintenancemaintenance

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MoistureMoisture Cold air holds less moisture than Cold air holds less moisture than

warm air.warm air.•Relative humidity is what matters

•If relative humidity is too high, liquid water can form (dew point)

•Heating air makes it “drier”

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Stack Effect, Stack Effect, CondensationCondensation

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Vapor BarrierVapor Barrier

Prevents air leakage and moisture Prevents air leakage and moisture inside wallsinside walls

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Top 10 Building Top 10 Building Science ConceptsScience Concepts

1. Heat flows from hot to cold1. Heat flows from hot to cold 2. Heat does not rise—warm air rises2. Heat does not rise—warm air rises 3. Heat is transferred by conduction, 3. Heat is transferred by conduction,

convection, radiationconvection, radiation 4. Heat flow through insulation is 4. Heat flow through insulation is

slowed by trapped air or other gasesslowed by trapped air or other gases 5. Air-tightness prevents major heat 5. Air-tightness prevents major heat

lossloss

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Top 10 Building Science Top 10 Building Science Concepts (cont.)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

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WeatherizationWeatherization

The practice of The practice of Protecting a building and its interior Protecting a building and its interior

from elements from elements Modifying a building to reduce energy Modifying a building to reduce energy

consumption and optimize consumption and optimize energy energy efficiencyefficiency

What kinds of things do we focus on?What kinds of things do we focus on? Sealing air leaks, adding insulation, Sealing air leaks, adding insulation,

replacing windows, new siding, etc…replacing windows, new siding, etc…

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Dennis’ ChartDennis’ Chart

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Sealing LeaksSealing Leaks

Air leaks are greatest Air leaks are greatest source of heat loss in source of heat loss in most homesmost homes

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What about fresh air?What about fresh air?

At least 15 cubic feet/minute (cfm) At least 15 cubic feet/minute (cfm) for a healthy, non-smoking home for a healthy, non-smoking home *ASHRAE*ASHRAE

Where does this air come from?Where does this air come from?

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Can Weatherization Can Weatherization Affect Health?Affect Health?

Can make house warmer, less draftyCan make house warmer, less drafty Heat Recovery Ventilators can filter Heat Recovery Ventilators can filter

air from outdoorsair from outdoors Can reduce amount of fresh air in Can reduce amount of fresh air in

homehome Construction (and destruction) can Construction (and destruction) can

produce dust, VOCs, disturb mold produce dust, VOCs, disturb mold spores, etc.spores, etc.

Can a house be “too tight?”Can a house be “too tight?”

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Why Do We Need Outside Why Do We Need Outside Air?Air?

Indoor air is usually Indoor air is usually worse worse for youfor you Humidity can be too high or too lowHumidity can be too high or too low

Mold, bacteria, dry lungsMold, bacteria, dry lungs Products of combustionProducts of combustion

CO, COCO, CO22, NO, NOXX, other, other Soot from boiler or woodstoveSoot from boiler or woodstove

Dust, pet dander, pest wastes, etcDust, pet dander, pest wastes, etc OdorsOdors Pathogens (germs)Pathogens (germs)

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What happens when What happens when we reduce ventilation?we reduce ventilation?

Unhealthy levels of gases and particulates Unhealthy levels of gases and particulates can build upcan build up

In schools and offices, performance In schools and offices, performance decreases, absenteeism increasesdecreases, absenteeism increases

Healthy people develop respiratory Healthy people develop respiratory problemsproblems

Existing respiratory problems are Existing respiratory problems are exacerbatedexacerbated

Air can smell bad Air can smell bad Air can become too humid (damp)Air can become too humid (damp)

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What to do?What to do?

Tightening buildings is good for Tightening buildings is good for energy, but can be bad for healthenergy, but can be bad for health

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Build it Tight, Ventilate Build it Tight, Ventilate it Rightit Right

Be aware of health implications of Be aware of health implications of tightening housestightening houses

Modern ventilation systems (HRVs) can Modern ventilation systems (HRVs) can enhance human health while conserving enhance human health while conserving heatheat

Traditional ventilation (bathroom fan, Traditional ventilation (bathroom fan, range hood, windows) valuable if used range hood, windows) valuable if used correctlycorrectly

Education of residents paramountEducation of residents paramount

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QuyanaQuyana

Questions?Questions?

Leif AlbertsonBethel, Alaskalflea@uaf.edu(907)543-4553