Insulation

Efficient technology 

On average, Californians use 9% of their electricity and 20-25% of their total home energy consumption annually on heating and cooling. That’s about $96 on electricity and $280 on total home energy per year for heating and cooling which, according to the California Energy Commission, can be cut by 30-50% with proper insulation of a non-insulated home. The effectiveness of insulation is rated by its R-value, a measurement of its resistance to heat transfer, with higher R-values signifying improved insulating properties.  The R-value and amount of insulation necessary to provide a proper resistance to heat flow depends on the location in your home, type of material, and amount of insulation already installed.

Not all insulation is created equal

Insulating some areas of your home are easier and more cost-effective than others.   A home energy survey can help you determine which areas you should insulate first.

Attic

Generally, the attic is easiest to insulate for a single family home, and it’s also the area where a large amount of energy enters and leaves a home. 

Types of Attics:

• No floor:  to add more insulation, place new unfaced batt insulation perpendicular to existing insulation to make sure joists are covered. 
• Attic floor:  Remove floor before adding insulation.  According to the Rocky Mountain Institute, 12 inches of insulation will be cost-effective in most climates.  Precautions:  be careful to not step through the uncovered space, into the ceiling below.
• Finished attic with cathedral ceiling:  Requires removing the roof, installing rigid material, and then re-roofing.  A contractor should do this and the labor and materials costs may be quite expensive.  Attic insulation in this case may not be as cost-effective as other weatherization measures.
• No Attic:  You can install insulation on the underside of the roof system rather than the floor.  Hire a qualified contractor if you choose to install this type of insulation properly.

Walls

Adding wall insulation is more complicated than adding attic insulation, typically requiring the skills of a qualified contractor.  Your home’s walls account for the greatest area of the building’s exterior so adding wall insulation can be more costly than adding attic insulation,.  Consult a home energy auditor or qualified contractor to see if wall insulation will be cost-effective for your home.

Types of Walls:

• Finished:  Loose-fill insulation is a good choice for existing finished walls, as installation doesn't disturb the existing wall too much.
• Unfinished interior walls:  If you have an addition being installed to your home, you can easily install blanket or batt insulation between the framing studs.
• Exterior walls:  If you're replacing the exterior siding of your home, you may want to take the opportunity to add rigid board insulation to the exterior of your home, installed by a qualified contractor.

Foundation, basement, and crawlspace

Up to 20% of the heat in your home may be escaping through an uninsulated foundation. Insulating around the edge of a slab-on-grade foundation can pay for itself in energy savings in 5-10 years.  It's good practice to consider insulating finished or unfinished basements, and crawlspaces as well. 

How much will I need?

The amount of insulation you install will depend on your climate, type of insulation, home construction parameters, fuel type, and your energy-efficiency goals.  Use the U.S. Department of Energy’s (DOE) ZIP-Code Insulation Program and R-value Recommendations to guide you.  Or, to get the most accurate recommendation, hire a professional to perform an energy audit on your home.