Energy Saving Devices

Archive for May, 2009

If you have or will have an unventilated crawl space, then your best approach is to seal and insulate the foundation walls rather than the subfloor. The advantages of insulating the crawl space are as follows:

* You can avoid the problems associated with ventilating a crawl space.
* Less insulation is required (around 400 square feet for a 1,000-square-foot crawl space with 3-foot walls.)
* Piping and ductwork are within the conditioned volume of the house so they don’t require insulation for energy efficiency or protection against freezing.
* Air sealing between the house and the crawl space is less critical.

The disadvantages of insulating a crawl space include the following:

* The insulation may be damaged by rodents, pests, or water.
* A radon mitigation system will require ventilation of the crawl space to the exterior. Not planning for radon-resistant construction may necessitate air sealing the floor to mitigate the radon through ventilation.
* The crawl space must be built airtight, and the air barrier must be maintained.
* The access door to the crawl space must be located inside the home through the subfloor unless an airtight, insulated access door in the perimeter wall is built and maintained.

Source: EERE, U.S. Department of Energy

If you properly insulate your crawl space—in addition to air sealing and controlling moisture, you will save on energy costs and increase your home’s comfort.

Before insulating or deciding whether to add insulation to your crawl space, first see our information about adding insulation to an existing house or selecting insulation for new home construction if you haven’t already.

How to insulate a crawl space depends on whether it’s ventilated or unventilated. Traditionally, crawl spaces have been vented to prevent problems with moisture; most building codes require vents to aid in removing moisture from the crawl space. However, many building professionals now recognize that building an unventilated crawl space (or closing vents after the crawl space dries out following construction) is the best option in homes using proper moisture control and exterior drainage techniques. There are two main reasons for this line of thinking:

* Ventilation in the winter makes it difficult to keep crawl spaces warm
* Warm, moist outdoor air brought into the crawl space through foundation vents in the summer is often unable to dehumidify a crawl space. In fact, this moist outdoor air can lead to increased moisture levels in the crawl space.

Source: EERE, U.S. Department of Energy

Liquid foam insulation products and installation usually cost more than traditional batt insulation. However, liquid foam insulation also forms an air barrier. This can help eliminate some of the other costs and tasks associated with weatherizing a home, such as caulking, applying housewrap and vapor barrier, and taping joints. When building a new home, this type of insulation can also help reduce construction time and the number of specialized contractors, which saves money.

Source: EERE, U.S. Department of Energy

Liquid foam insulation—combined with a foaming agent—can be applied using small spray containers or in larger quantities as a pressure-sprayed (foamed-in-place) product. Both types expand and harden as the mixture cures. They also conform to the shape of the cavity, filling and sealing it thoroughly.

Slow-curing liquid foams are also available. These foams are designed to flow over obstructions before expanding and curing, and they are often used for empty wall cavities in existing buildings. There are also liquid foam materials that can be poured from a container.

Installation of most types of liquid foam insulation requires special equipment and certification. Therefore, you’ll probably want a certified insulation installer to do it.

Following installation, an approved thermal barrier—such as drywall—must cover all foam materials. Also, some building codes don’t recognize sprayed foam insulation as a vapor barrier, so installation might require an additional air barrier, like polyethylene or some other vapor retarder.

Source: EERE, U.S. Department of Energy

Liquid foam insulation materials can be sprayed, foamed-in-place, injected, or poured. Their ability to fill even the smallest cavities gives them twice the R-value per inch than traditional batt insulation.
Types of Liquid Foam Insulation

Today, some foam insulation consists of materials similar to those found in pillows and mattresses. Also, most foam materials can now be used with foaming agents that don’t use chlorofluorocarbons (CFCs) or hydrochlorofluorocarbons (HCFCs), which are harmful to the earth’s ozone layer.

Some types of available liquid foam insulation materials include these:

* Cementitious
* Phenolic
* Polyisocyanurate
* Polyurethane.

Some less common types include Icynene foam and Tripolymer foam. Icynene foam can be either sprayed or injected, which makes it the most versatile. It also has good resistance to both air and water intrusion. Tripolymer foam—a water-soluble foam—is injected into wall cavities. It has excellent resistance to fire and air intrusion.

Urea-formaldehyde (UF) foam was used in homes during the 1970s and early 1980s. It is no longer available for residential use because of health-related concerns.

Source: EERE, U.S. Department of Energy

Insulation blown into your ceiling cavities should cover the top plate of the wall, but be sure the eave vents are not covered. These vents provide necessary ventilation to your attic, and covering them could result in severe moisture problems.

Electrical devices and recessed lights (except “IC-rated” fixtures) require 3 inches (8 centimeters) of clearance from insulation.

Pipes for kitchen stoves, wood stoves, and furnaces should only be insulated with fiberglass or rock wool because cellulose may smolder if flue temperatures become hot enough.

Some observers contend that fiberglass particles can cause cancer if inhaled. Others state that the fire retardants and insecticides added to cellulose may be harmful to breathe. While the debate continues as to the health effects of loose-fill insulations, it is important to protect yourself when installing any type of insulation. Wear a quality respirator, protective eyewear, and clothing such as goggles, gloves, long-sleeved shirts, and pants to minimize contact with the insulation.

Insulation fibers can also be drawn into air distribution systems if the ducts are not properly sealed, allowing the fibers to circulate within the living space. Be sure to seal all of your home’s ductwork, as well as any other openings where insulation could leak out of the wall or ceiling cavities and into your living space.

Source: EERE, U.S. Department of Energy

To ensure quality installation, whether you hire a professional or do it yourself, you should also look for voids and gaps, and fluffing.

Voids and gaps occur if insulation is installed at too low a density or if a cavity isn’t completely filled. Voids also occur if the installation holes are improperly located between the vertical framing studs or if there are too few fill holes.

Fluffing occurs when insulation is installed to minimum thickness but not to minimum weight requirements. The result is a less dense application of insulation that requires fewer bags. When insulation is fluffed, air passes more easily through it. This means increased heat loss. Additionally, the fluffed loose-fill insulation will eventually settle, resulting in a loss in thermal resistance or R-value. Fiberglass is more “fluffable” than cellulose or rock wool.

Intentional fluffing by unscrupulous contractors has been a problem in some parts of the country. To avoid these problems, compare bids from several contractors to see how many bags they specify. Count the number of bags used during installation, either by you or a contractor, and compare it to the instructions on the bag. The manufacturer should specify the amount of insulation required to obtain a particular R-value per square foot (or square meter) of space.

Source: EERE, U.S. Department of Energy

Over time, loose-fill insulation can lose its installed R-value because of settling, especially in attic cavities. Cellulose settles more than rock wool or fiberglass—20% compared to 2%–4%. Therefore, if you use cellulose, install 20% more in an attic to offset the settling. Cellulose manufacturers are required by federal law to provide the “settled thickness” on their bags. Some even provide the “installed thickness.”

Researchers say it’s possible to install loose-fill insulations in wall cavities without settling. If the cavity is completely filled with insulation at the proper density, no significant settling should occur. A general density guideline for walls is roughly 3.5 pounds per cubic foot (17 kilograms per cubic meter) of wall cavity for cellulose and 1.5 pounds per cubic foot (7 kilograms per cubic meter) for fiberglass or rock wool. These specifications are roughly twice the density of horizontal applications.

Here’s an easy-to-follow guideline to ensure that wall cavities are being filled at a density sufficient to prevent settling: use roughly one 30-pound (13-kilogram) bag of cellulose or about 15 pounds (8 kilograms) of fiberglass or rock wool for every three wall cavities you fill. (Assumptions: 8-foot [2.4-meter] walls, with 16-inch [41-centimeter] on-center wall cavities, and 2×4-inch framing studs.)

Source: EERE, U.S. Department of Energy

Loose-fill insulation can be installed in either enclosed cavities, such as walls, or unenclosed spaces, such as attics. Installation usually involves using special equipment that blows the insulation through and into the cavity or space. This includes the “two-hole method,” which entails drilling two holes spaced vertically between the exterior walls’ framing studs. The holes should be 2 inches (5 centimeters) in diameter. Working between each stud, drill one hole 16 inches (41 centimeters) from the top of the wall. Drill the other hole 24 inches (61 centimeters) from the bottom of the wall. Blow the insulation into the holes and then seal the installation holes. In conventional and cathedral ceilings, insulation is easier to blow in if an access opening through the ceiling already exists. Otherwise, it may be necessary to drill holes in the ceiling or between the roof rafters.

Installation is most commonly done by professionals who are experienced at operating the equipment to ensure proper density and complete coverage. If you’d like to have the insulation installed professionally, you should do the following:

* Obtain written cost estimates from several contractors for the R-value you need. Don’t be surprised to find quoted prices for a given R-value installation to vary by more than a factor of two.

* Ask contractors about their air-sealing services and costs as well, if needed.

If you want to install it yourself, you should try to obtain instructions and safety precautions from the insulation manufacturer. Carefully follow these instructions. You should also check your local building and fire codes.

Source: EERE, U.S. Department of Energy

The most common types of materials used for loose-fill insulation include cellulose, fiberglass, and mineral (rock or slag) wool. All of these materials are produced using recycled waste materials. Cellulose is primarily made from recycled newsprint. Most fiberglass contains 20%–30% recycled glass. Mineral wool is usually produced from 75% post-industrial recycled content.

Some less common types of loose-fill insulation include polystyrene beads and vermiculite and perlite.

Source: EERE, U.S. Department of Energy