Walls of Structure

Decreasing the Decreasing the Amount of Heat Amount of Heat

ExchangeExchange

Decreasing Power BillDecreasing Power Bill

How can we decrease our power How can we decrease our power bill?bill?

What are things in our home now What are things in our home now that keep our bill low?that keep our bill low?

What are some things we can do to What are some things we can do to our home to decrease this even our home to decrease this even further?further?

Wall SectionWall Section

What are house walls What are house walls made of?made of?

If I were to cut a cross If I were to cut a cross section of the wall, section of the wall, what would it look like?what would it look like?

What are different What are different materials used to form materials used to form our walls?our walls?

Picking the MaterialPicking the Material

What do you want the appearance What do you want the appearance of the structure to be?of the structure to be?

How efficient do you want the How efficient do you want the structure to be?structure to be?

How much money do you have to How much money do you have to spend? (Now and throughout the life spend? (Now and throughout the life of the building)of the building)

R valueR value

Ranking given to all materials used Ranking given to all materials used in wallsin walls

A measure of a material’s resistance A measure of a material’s resistance to heat flowto heat flow• Higher R value = better the qualityHigher R value = better the quality

• Better quality means less heat lostBetter quality means less heat lost

Determining R ValueDetermining R Value

Every material has a set valueEvery material has a set value• Value chartValue chart

Look at everything included in the Look at everything included in the wallwall• List them, find R values, add them List them, find R values, add them

togethertogether

• Determine Determine final R value

Getting High R ValueGetting High R Value

Pick insulationPick insulation• Largest factor in determining R valueLargest factor in determining R value

• Amount used can be affected by Amount used can be affected by location, climate, and price (of location, climate, and price (of insulation and utilities) insulation and utilities)

Pick your exterior coveringPick your exterior covering• Can also greatly affect R valueCan also greatly affect R value

Amount of Insulation to UseAmount of Insulation to Use

U ValueU Value

The inverse of the R valueThe inverse of the R value Measure the the products Measure the the products

conductivity of heatconductivity of heat The lower the U value, the better The lower the U value, the better

insulating quality of the productinsulating quality of the product

““R” Value and “U” Value R” Value and “U” Value The “R” value is a measurement of heat loss The “R” value is a measurement of heat loss

retardation characteristics of a building component. retardation characteristics of a building component. For example increasing the thickness of an For example increasing the thickness of an insulating material increases the “R” value. The “U” insulating material increases the “R” value. The “U” value is the inverse of “R” value. “U” value value is the inverse of “R” value. “U” value describes how well a building element conducts describes how well a building element conducts heat. It measures the rate of heat transfer through a heat. It measures the rate of heat transfer through a building element over a given area, under building element over a given area, under standardized conditions, and therefore lower “U” standardized conditions, and therefore lower “U” value numbers mean higher levels of energy value numbers mean higher levels of energy conservation. Both “R” and “U” values are conservation. Both “R” and “U” values are commonly used in building component commonly used in building component discussions. discussions.

Source: http://www.adobe-home.com/faqs/glossary-of-terms/

How to Use R ValueHow to Use R Value

Determine Heat Loss in wallDetermine Heat Loss in wall

Q = Heat lossQ = Heat loss A = Area of surfaceA = Area of surface TTII = Inside temperature = Inside temperature

TToo = Outside temperature = Outside temperature

Q =A(TI – To)

R

Heat LossHeat Loss

Q is figured in units of BTU/hrQ is figured in units of BTU/hr• BTU = British Thermal UnitsBTU = British Thermal Units

• Amount of energy needed to raise the Amount of energy needed to raise the temperature of 1 pound of water 1°Ftemperature of 1 pound of water 1°F

Heat LossHeat Loss

Figure the amount of heat loss to Figure the amount of heat loss to determine how efficient your home determine how efficient your home or business isor business is

More heat lost = higher your power More heat lost = higher your power billbill• More energy needed to replace the More energy needed to replace the

heat that is lostheat that is lost

How is Heat Lost?How is Heat Lost?

Through walls and ceilings (roofs)Through walls and ceilings (roofs)• Look at R values to determine thisLook at R values to determine this

Through windows and doorsThrough windows and doors• Known as infiltration heat lossKnown as infiltration heat loss

35-50% heat loss35-50% heat loss

Stopping Air LeaksStopping Air Leaks

Weatherizing Weatherizing • the process of stopping air leaksthe process of stopping air leaks

Add storm doorsAdd storm doors Add storm windows or more panes Add storm windows or more panes

of glassof glass• Air inside the panes of glass offers Air inside the panes of glass offers

additional insulating valueadditional insulating value

Caulking / WeatherstrippingCaulking / Weatherstripping

Filling cracks around anything that Filling cracks around anything that penetrates to the outsidepenetrates to the outside

Variety of types and colorsVariety of types and colors• Select caulking that has a long warranty and will Select caulking that has a long warranty and will

be remain flexible rather than become brittlebe remain flexible rather than become brittle• The felt and rubber weatherstriping types are The felt and rubber weatherstriping types are

considered temporary, while metal/rubber considered temporary, while metal/rubber combination types are more permanentcombination types are more permanent

Door ThresholdsDoor Thresholds

Fastened to the floor under the Fastened to the floor under the bottom edge of a door to prevent air bottom edge of a door to prevent air leaksleaks• It may be wood or a combination of It may be wood or a combination of

metal and rubber.metal and rubber.

Total Heat Loss of a BuildingTotal Heat Loss of a Building

We have a 24’ x 30’ building with 10’ walls. The We have a 24’ x 30’ building with 10’ walls. The walls are made of vinyl siding with ½” insulating walls are made of vinyl siding with ½” insulating board, ½” plywood sheathing, 4” of blown in board, ½” plywood sheathing, 4” of blown in cellulose insulation, and ½” drywall. The walls are cellulose insulation, and ½” drywall. The walls are supported by 2 x 4 studs that make up 15% of the supported by 2 x 4 studs that make up 15% of the wall. There is a 2’10” x 6’ 8” wood, 2 ¼” solid core wall. There is a 2’10” x 6’ 8” wood, 2 ¼” solid core flush door and 10% of the walls are double pane flush door and 10% of the walls are double pane widows with ¼” air space. It also has a ceiling made widows with ¼” air space. It also has a ceiling made of ½” drywall and 6” of blown in cellulose insulation. of ½” drywall and 6” of blown in cellulose insulation. The infiltration rate of the building is 35%. On a 0°F The infiltration rate of the building is 35%. On a 0°F day, what would the heat loss of the building be if it day, what would the heat loss of the building be if it was 70°F inside?was 70°F inside?

Total Heat Loss of a BuildingTotal Heat Loss of a Building

The walls are made of vinyl siding The walls are made of vinyl siding with ½” insulating board, ½” with ½” insulating board, ½” plywood sheathing, 4” of blown in plywood sheathing, 4” of blown in cellulose insulation, and ½” drywall. cellulose insulation, and ½” drywall. The walls are supported by 2 x 4 The walls are supported by 2 x 4 studs that make up 15% of the wall. studs that make up 15% of the wall.

R = 17.307

Total Heat Loss of a BuildingTotal Heat Loss of a Building

We have a 24’ x 30’ building with 10’ We have a 24’ x 30’ building with 10’ walls. walls.

2’10” x 6’ 8” door2’10” x 6’ 8” door

10% windows10% windows

A = 1080 ft2

A = 1061.11 ft2

A = 954.999 ft2

Total Heat Loss of a BuildingTotal Heat Loss of a Building

Inside temperature is 70°F and Inside temperature is 70°F and outside temperature is 10°Foutside temperature is 10°F

Heat loss of wallHeat loss of wall

T = 70°F

Q = 3862.59 BTU/hr

Total Heat Loss of a BuildingTotal Heat Loss of a Building

Heat loss of windowHeat loss of window

Heat loss of doorHeat loss of door

Q = 4395.13 BTU/hr

Q = 357.38 BTU/hr

Total Heat Loss of a BuildingTotal Heat Loss of a Building

It also has a ceiling made of ½” It also has a ceiling made of ½” drywall and 6” of blown in cellulose drywall and 6” of blown in cellulose insulation. insulation.

Ceiling areaCeiling area

R = 22.83

A = 720 ft2

Total Heat Loss of a BuildingTotal Heat Loss of a Building

Heat loss of ceilingHeat loss of ceiling

Heat loss of all parts of the buildingHeat loss of all parts of the building

Q = 2207.62 BTU/hr

Q = 10822.72 BTU/hr

Total Heat Loss of a BuildingTotal Heat Loss of a Building

The infiltration rate of the building is The infiltration rate of the building is 35%. 35%.

Overall Total Heat Loss Overall Total Heat Loss

Q = 3787.952 BTU/hr

Q = 14610.672 BTU/hr