OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable...that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliancestandards, and guidelines forefficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

INTRODUCTIONThe primary foundations in the United Statesare slab-on-grade, crawlspace, and basement.Basements can be a good choice for sites thatslope steeply and in climates having coldwinters with deep frost penetration. Althoughdeeper excavation is required for structuralreasons, the additional cost can result in acomfortable and habitable space.Basements are notorious for problems withwater intrusion, cold temperatures, humidity,mold, and uncomfortable, if not unhealthy,living conditions. A properly sealed, insulated,and moisture-protected basement will increasecomfort, save on energy costs, improvedurability, and reduce entry of moisture, soilgases, and other potential irritants orpollutants into the home.However, basement walls are one of the mostcontroversial areas of a home to insulate andseal. Many builders, even in far northernstates, feel that insulating basement walls is

too expensive and does not provide a reasonable payback. Also, builders of daylight orwalkout basements often only insulate theframed section of the basement. Yet energycodes typically require a thermal boundarybetween the house and unconditionedbasement or between a conditioned basementand the outside air and earth.KEYS TO AN EFFECTIVE BASEMENTMoisture control – using a water-managedfoundation system to drain rainwater andgroundwater away from foundations.Airtight construction – sealing all air leaksbetween the conditioned space and theoutside prior to insulation installation.Complete insulation coverage – properlyinstalling the correct insulation levels, makingsure the insulation coverage is continuous andcomplete, and aligning the insulation barrierwith the air barrier.

ANNUAL SAVINGS WITH BASEMENT WALLINSULATIONThe energy savings of basement wallinsulation vary depending on the localclimate, type of heating system, cost ofenergy, and lifestyle of the occupant.Typical annual savings are provided in thetable for a standard, 1,500 square-foothome with a conditioned basement that isheated by natural gas ($0.72/therm).

$ 0 052 92$

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rete, or wood. These tiny cracks

n any direction–even upward.

venting these problems will

and style of construction, but the

 to most basement designs.

aterials away from earth contact.

gutters, to conduct rainwater away

 all sides of the house for at least

rade (3 inches in 5 feet). Establish

ainwater around the house.

e air sealing.

ane, such as caulked metal flashing

to serve as a capillary break that

up from the masonry foundation

lso serve as a termite shield on top

e portions of the foundation wall

 wall from absorbing ground

n.

ge plane over the dampproofing or

nel water to the foundation drain

ssure. Drainage plane materials

atts, high-density fiberglass

ashed gravel. All drainage planes

 filter fabric to prevent dirt from

ps in the drainage material.

directly below the drainage plane

t on top of the footing. This

ng against the seam between the

 wall. Surround a perforated 4-inch

el and wrap both with filter fabric.

s slab floor, install a capillary break

ting of a layer of 6- to 10-mil

4 inches of gravel.
preferable to insulating the basement ceiling.Advantages of basement wall insulation include:• Basement spaces, whether conditioned or not, are warmer and

more comfortable.

• Compared to insulating the basement ceiling, insulating

basement walls:— requires less insulation (1,350 square feet of wall

insulation for a 36- by 48-foot basement with 8-foot walls,compared with 1,725 square feet of basement ceilinginsulation),

— more easily achieves continuous thermal and air leakage

boundaries because basement ceilings are typicallypenetrated with electrical wiring, plumbing, and ductwork,

— requires little, if any increase in the size of heating and

cooling equipment–the heat loss and air leakage throughthe basement ceiling is similar to that through the exteriorwalls of the basement.

• Piping and ductwork are located within the conditioned

volume of the house so they do not require insulation forenergy efficiency or protection against freezing.

insulation

Drywall

1x2 furring strips with 2 layers of foaminsulation

Disadvantages of basement wall insulation include:• Costs may exceed those for insulating the basement ceiling,

depending on the materials and approach selected.

• If the surrounding soil contains radon gas, the home will

require a mitigation system underneath the basement floor.

• In termite-prone areas, exterior foam insulation in ground contact

allows a path for termites to access the walls of the home undetected. Check with local code officials to determine acceptanceof exterior foam application. Some installations will requirenon-invasive termite detection systems, such as termite baits.One of the nation’s leading foam insulation manufacturers hasreleased a rigid foam with borate insect repellent.

R-VALUES RECOMMENDED FOR BASEMENT INSULATIONThe International Energy Conservation Code’s basement wallinsulation requirements, based on Heating Degree Days (HDD),are as follows:

HDD Zone R-value R-value

Interior Exterior

1 (0-1,500) none none2 (1,501-4,500) R-5 to R-9 R-5 to R-103 (4,501-8,500) R-9 to R-10 R-104 (8,501-9,000) R-10 to R-19 R-10 to R-155 (> 9,000) R-19 R-15

12345

HDD=HEATING DEGREE DAYSConsult your local weather bureau for your city’s actualHeating Degree Days, a measurement commonly used todetermine fuel consumption and/or the cost of heatingduring a heating season.
OFFICE OF BUILDING TECHNOLOGY, STATE AND COMMUNITY PROGRAMSENERGY EFFICIENCY AND RENEWABLE ENERGY • U.S. DEPARTMENT OF ENERGY

Buildings forthe 21st CenturyBuildings that are moreenergy efficient, comfortable,and affordable...that’s thegoal of DOE’s Office of BuildingTechnology, State andCommunity Programs (BTS).To accelerate the developmentand wide application of energyefficiency measures, BTS:• Conducts R&D on technologies

and concepts for energy efficiency, working closely withthe building industry and withmanufacturers of materials,equipment, and appliances

• Promotes energy/money

saving opportunities to bothbuilders and buyers of homesand commercial buildings

• Works with state and local

regulatory groups to improvebuilding codes, appliancestandards, and guidelines forefficient energy use

• Provides support and grants

to states and communitiesfor deployment of energyefficient technologies andpractices

INTRODUCTIONThe primary foundations in the United Statesare slab-on-grade, crawlspace, and basement.Basements can be a good choice for sites thatslope steeply and in climates having coldwinters with deep frost penetration. Althoughdeeper excavation is required for structuralreasons, the additional cost can result in acomfortable and habitable space.Basements are notorious for problems withwater intrusion, cold temperatures, humidity,mold, and uncomfortable, if not unhealthy,living conditions. A properly sealed, insulated,and moisture-protected basement will increasecomfort, save on energy costs, improvedurability, and reduce entry of moisture, soilgases, and other potential irritants orpollutants into the home.However, basement walls are one of the mostcontroversial areas of a home to insulate andseal. Many builders, even in far northernstates, feel that insulating basement walls is

too expensive and does not provide a reasonable payback. Also, builders of daylight orwalkout basements often only insulate theframed section of the basement. Yet energycodes typically require a thermal boundarybetween the house and unconditionedbasement or between a conditioned basementand the outside air and earth.KEYS TO AN EFFECTIVE BASEMENTMoisture control – using a water-managedfoundation system to drain rainwater andgroundwater away from foundations.Airtight construction – sealing all air leaksbetween the conditioned space and theoutside prior to insulation installation.Complete insulation coverage – properlyinstalling the correct insulation levels, makingsure the insulation coverage is continuous andcomplete, and aligning the insulation barrierwith the air barrier.

ANNUAL SAVINGS WITH BASEMENT WALLINSULATIONThe energy savings of basement wallinsulation vary depending on the localclimate, type of heating system, cost ofenergy, and lifestyle of the occupant.Typical annual savings are provided in thetable for a standard, 1,500 square-foothome with a conditioned basement that isheated by natural gas ($0.72/therm).

$ 0 250 $29

U.S. Cities R-10* R-20**

Buffalo, NY $350 $390

Denver, CO $310 $360

Minneapolis, MN $400 $450

Seattle, WA $280 $320

St. Louis, MO

Washington, DC $ 0 250 $28

* Such as 2 to 3 inches of exterior foam insulation.

** Such as with most insulated concrete forms.

d with a renewable-source ink on paper containing at

50% wastepaper, including 20% postconsumer waste.

ry 2002 DOE/GO-102002-0776

CONTROL IN BASEMENTS

radioactive gas that occurs in some

n enter a home through the founda

or system. If it occurs in concen

eater than 4 pico-curies per liter, it

a health risk to the home occupants.

gainst radon problems:

 4-inch or greater gravel base with a

ous layer of 6-mil polyethylene on

he gravel.

a “T” fitting attached to a 3-inch or

iameter gas-tight pipe through the

ylene barrier into the sub-slab

ate before the slab is poured.

e slab and seal all slab joints and

tions.

the gas-tight pipe vertically through

ior wall and terminate it at least 12

above the roof.

n electrician stub-in a junction box in

c.

nstruction is complete, test the

nt for radon with an EPA-listed radon

 or hire a qualified technician. If the

ows concentrations above 4 pico

er liter, install a small blower to the

the attic to depressurize the sub-slab

f use of the blower does not reduce

evels below 4 pico-curies per liter,

 with local radon experts.

etailed instructions, visit the EPA

 site http://www.epa.gov/iaq/radon/.