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Energy Efficient Housing

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Why construct energy efficient structures? Bottom Line !!! Money It may save up to 60% of the cost

to heat/cool the structure

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Model Energy Code

A national minimum standard for energy efficient residential construction developed by CABO (Council of American Building Officials)

Incorporates the use of select building materials to maximize energy efficiency

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Basic Considerations:

Shape of Structure Structural Features & Materials

Used Orientation

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Shape of Structure

Ideal shape is a square If the structure is long and narrow,

it is less energy efficient

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R –Value as Related to Building Material Features

R-Value defined: a numerical measure of resistance to the flow of heat; the higher the R-value, the greater the resistance to heat flow

Specific resistance of any material is directly related to it’s thickness

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Examples of R- value’s (per one inch of material):

Batts or blanket insulation – 3.14 Rigid board insulation – 3.8 to 4.8 Cellulose (loose blown) – 2.8 to 3.7 Extruded polystyrene – 4.0 to 6.0

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Recommended R-values by regions:

0

5

10

15

20

25

30

35

40

Ceiling Wall Floor

South

Mid West

North

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U - Value

The number of BTU’s (British Thermal Units) per hour that will flow through 1 sq. ft. of the structure when there is a 1 degree difference in temperature between the 2 sides.

The higher the U-value; the more heat will be lost

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Features to consider: 6 “ exterior walls ( 2”x 6” @ 24”o.c.) R- 19 12” insulation in ceiling R-38 (min. 30) Extended overhang (30” to 36”) Insulate slab Insulate between floor joists (6 “) Heat ducts inside heated area Install dehumidifier Heat pump Continuous soffit vents

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Features (con’t):

Continuous ridge vent or thermostatically controlled roof vents

Mastic under base plate Insulated doors (R-10 min.) Insulated windows or storm windows Insulate water pipes

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Orientation:

Try to build narrow end of building running East and West because of the greater heat gain from the sun

In winter, windows on the South side of the structure will catch “free” heat from the sun

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Thermal Envelopes

Any exit or entry point in the envelope is a potential place for heat to enter or escape.

Seal all such locations with the appropriate materials/methods.

Examples: around doors (weather stripping)

Can you think of other areas of concern ?