It is definitely not sexy, or even much to look at, but insulation is one building product that saves energy and money. Most don’t give it much thought until the utility bills come weeks into the heating season. As well-known as the fluffy pink rolls are, there are some misconceptions about insulation and the part it plays in energy efficiency.
Insulation alone will not make a house energy efficient. It must be combined with air-sealing products that keep conditioned air from escaping through cracks and gaps. “Insulation retains heat, but it does not stop airflow,” said Jaime Pereira, director of business development for Powersmith Home Energy Solutions in Copiague. “When we go into an attic, we often see old fiberglass insulation and there are gaps everywhere. It is not creating a consistent thermal barrier.”
In the attic those leaky gaps include penetrations for plumbing and electrical lines, chimneys and vents, ductwork, recessed ceiling lights and the area around the attic door or hatch. The tools used to fill the voids are commonplace: caulk, canned spray foam or weather stripping around doors and windows. While insulation is not the only component of an energy efficiency home, it is an important one. All insulation has a printed R-value rating, which is a measure of a 1-inch-thick sample of a material’s ability to resist heat flow—the higher the R-value, the better the insulator. The most common options on the market include:
Fiberglass is the most popular type of insulation used in attics, walls and floors over crawl spaces. It is available in batts or blankets that are designed to fit snugly between ceiling joists or wall studs. Fiberglass loose fill is blown into attics and walls with special equipment. The material’s R-value is 3 to 4 per inch and costs about $.65 to $1.10 per square foot for an R30 batt (which is 7 to 8 1/2-inches thick).
Cellulose is another common material used to insulate attics and walls. It is made from ground-up recycled newspapers treated with a fire retardant and has an R-value similar to fiberglass. It’s a blown-in insulation, which requires additional equipment. To obtain an R30 (more on this benchmark below) for either cellulose or loose-fill fiberglass expect to pay between $.50 and $1.50 per square foot.
Rigid foam insulations, also called foam boards, range from R3.8 to 5 for polystyrene to about R6.5 to 8 for polyurethane. They are a popular option when re-siding with new vinyl or wood shingles because the foam insulates the wall and provides some measure of air sealing. For 1-inch thick boards, prices start from about $.60 per square foot for polystyrene to about $.85 for polyurethane.
Spray foam polyurethanes are used mainly in new construction where walls are open. The foam expands as it cures, filling nooks and crannies, forming an air barrier and insulator. One-inch-thick closed-cell foam has an R-value between 5.5 and 6.5 and starts at about $1.80 per square foot when applied by a contractor.
Warm Up Long Island
The Department of Energy recommends that houses here achieve R38 to R60 in attics and R25 to R30 for floors over unheated spaces. Homeowners can determine a home’s energy efficiency by getting a free energy audit as part of the Home Performance with Energy Star program.
Pereira described how it works: A certified energy auditor assesses the home. Then the program pays the upfront cost of improvements prescribed by the auditor. These may include insulation, air sealing and heating and cooling upgrades. Homeowners may be eligible for various rebates, including 10 percent off up to $3,000 or 50 percent off up to $5,000 depending on household income. Once the work is completed, qualified homeowners pay the state back only with the savings the efficiency work creates. The result is residential energy efficiency projects are now accessible to many homeowners who couldn’t otherwise afford them.