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Insulate your home and finances

By Alice La Pierre City of Berkeley Energy Office
Wednesday January 02, 2002

The holidays are over, and the bills are rolling in. While gas prices are currently lower than last year, there is no guarantee that they will remain that way. Unlike electricity, gas prices are unregulated, and as we experienced a year ago, prices can swing wildly out of control. 


What can you do to protect yourself from these price increases, and make your home more comfortable to live in at the same time? Insulate! Many older homes in the Bay area were built with little or no insulation in the basement, walls and ceiling, making them drafty and cold in winter, and hot in the summer. According to the US Department of Energy, "Each year the amount of energy lost through uninsulated homes in the United States is equivalent to the amount of oil delivered annually through the Alaskan Pipeline." Insulation and weatherstripping are the best way to save money, energy and even out the temperatures. 


Insulation comes in several forms and materials. In existing homes, many people use a loose, blown-in insulation to avoid having to tear out walls. Loose insulation can be made of fiberglass, vermiculite (gray or brown granules) recycled newspaper that has been fire-treated, or even denim and cotton fibers that have been treated. When loose insulation is used in walls, small round holes are cut into the upper wall and the insulation is blown in through a tube. Care should be taken that additional holes are cut beneath the fire stops (horizontal boards set into the stud wall to prevent a fire from climbing through the wall) and beneath windows so the wall will be completely insulated. In an attic, the material is blown evenly to a thickness of about 9 inches. 


For new homes or remodels, batts of insulation are also available, and are generally made of fiberglass. Batts can have a vapor barrier on them that reduces or prevents excess water molecules from passing through the wall. An aluminum vapor barrier will have the additional bonus of reflecting heat (or coolness) back into a room, keeping it far warmer than any other type of barrier. Care should be taken that the vapor barrier is placed on the surface closest to the interior of the room; i.e., in an attic, it should be placed on the bottom, against the ceiling. 


Rigid foam insulation can also be used, although it is less common in the Bay area. Rigid foam has the advantage of being easy to install, and far less messy than other types. It may also have a vapor barrier. It is more expensive, and less commonly available than other types of insulation. 


Never block the eaves and ventilation holes at the edges of the house. An attic must be vented to exhaust moisture and heat build up in summer. Blocking these vents will trap moisture, creating mold or mildew, and make an attractive habitat for termites and powder-post beetles. Also keep insulation away from recessed light fixtures, electrical fixtures, motors, bare stove or ventilation pipes, such as from a hot water heater. However, if you clear a space of insulation to install light fixtures or other things in the attic, be sure to go back and re-insulate. A gap in the insulation will act as a conduit, drawing heat rapidly out of your house. 


Homeowners should check their attics, and look for a couple of things: 1) what type of wiring is there, and 2) is there any insulation? If your home has older knob-and-tube insulation, it should be checked first by a licensed electrician (with a C-10 class license.) Knob-and-tube wiring needs air around it to release its heat; loose insulation may cover splices in the wiring and create a build-up of heat, making a potential fire hazard. If there are splices, have batts installed, and trim them around the wire so it can breathe. Be sure the vapor barrier is placed on the bottom. It is fine to increase layers of material to obtain the desired or required level of insulation. 


If your home has an accessible basement or crawlspace, insulation can be placed underneath and held in place with special wires made for this. This time, the vapor barrier should be placed facing up against the bottom of the floor. If your home has a garage with living space above it, insulation should also be placed on the ceiling of the garage, and a double-sided or encased batt used. 


Insulation comes in different thicknesses. They are classified by their rate of resistance to allow heat energy to transfer through, called an R-value. What R-value* of insulation should you use? Berkeley’s Residential Energy Conservation Ordinance (RECO) calls for a minimum of R-30 in the ceiling, between 8 and 13-1/2 inches of blown-in, depending on the type of material. Batts have labels on them indicating their R-value. If your home already has some insulation, you can always add more to bring it up to the minimum standard. If the ceiling has enough space, it is even better to increase the insulation to R-30 or greater, as long as there is enough space.  


Never pack insulation tightly into a space. Air pockets are what make insulation work. The more dense a material is, the less it insulates—think about how cold stone or tile is to the touch! It would take many feet of stone to create the same insulating value as a few inches of fiberglass. 


Once you have insulated your ceiling, walls and basement, you can concentrate on the rest of the places where energy is lost. Hot water pipes can easily be insulated with self-sealing material available from the BC&E Program*. Be sure to also insulate the first five feet of the cold-water inlet pipe to your hot water heater, as heat is also lost there. While you’re at it, insulate your gas hot water heater, and reduce the temperature to 115 F. degrees. Once you’ve done these steps, you should notice an immediate drop in your gas use. 


Furnace hot air ducts should be insulated; older furnace ducts should be checked to insure that there are no leaks. Don’t block the air return vents; air must be exhausted from the house to allow the warm air from the furnace in.  


Outlets and switches can easily be insulated with inexpensive foam gaskets. These take just a few minutes, and will immediately make your home less drafty. Window moldings should be caulked, and if there are gaps around the window sashes, they can be insulated with weatherstripping foam tape. 


Entry doors should have a raised threshold and a good weather-strip at the bottom to prevent air leaks. Installing a new threshold can be tricky; hire a contractor if you do not have the skills or equipment. Thresholds and weather-strip are also available through the BC&E Program. 


If you don’t use your fireplace, the flue should be permanently blocked and insulated, or removed completely. If you do use it, you may want to read an earlier PowerPlay column on heating with a fireplace. Visit the Energy Office Website at for  

online articles. 


Once your home is properly insulated and weatherized, the energy drain will be permanently stopped. Your home will feel much more comfortable with those drafts blocked, and better still, you will be better protected from fluctuating energy prices. For more information on insulating, the City Energy Office provides a home energy insulation guide, which is available at the Permit Service Center, 2120 Milvia Street. 


The BC&E Program (Berkeley Conservation and Energy) makes insulating and energy conservation equipment available at wholesale prices to the public. It is a partnership between the City of Berkeley, the Ecology Center, and Community Energy Services Corporation (CESC). Products are available at the Berkeley Farmers’ Markets and various local retailers in Berkeley. Visit the Energy Office website at for more information. 


* R-Value, or "resistance", is a measure of the amount of thermal resistance that a material has. The reciprocal of this is thermal conductance. The greater the R-value a material has, the greater its insulating value.