By Gregory Hafkin

	The diagram above illustrates the locations where insulation can be installed to make a difference in energy efficiency.

With energy prices rapidly on the rise, more and more builders are weighing insulation choices in an effort to lower utility bills for their customers. For existing homeowners, a remodeling could be the perfect time for strengthening insulation to further curtail the flow of heat in and out of the house.

R-values for insulation materials indicate how well the insulation resists heat flow, with higher numbers pointing to greater resistance. The U.S. Department of Energy has drafted recommended R-values for new homes based on the geographical location of the house, the part of the house that is being insulated, and how the house derives its energy. Homeowners can then use these guides to raise their R-values, either by increasing the thickness of the existing insulation or replacing it with materials that have higher resistance.

A popular way to insulate a house is to blow cellulose or fiberglass into an open space or cavity, such as an attic, in a method known as loose-fill insulation. Although fiberglass has long been the industry standard, cellulose, which is made of recycled newsprint, is gaining ground as earth-friendly construction enters the mainstream. Because of its tight seal, cellulose can also protect against air infiltration.

In addition to keeping heat from entering or escaping a house, insulation can also provide sound control. Cellulose provides better sound insulation than fiberglass, while another loose-fill material, mineral wool, has the added quality of being virtually fireproof. One advantage that all loose-fill products have is that they can be easily applied in a retrofitting job without disturbing the existing wall.

Fiberglass and mineral wool also come in batts and blankets, which are often used in new construction. Rigid foam insulation is particularly useful in places where homeowners are worried about water penetration, such as below ground level. Some insulation materials, such as urethane and Icynene, are sprayed on. They expand and harden after the spraying to strengthen the structure and avert air leakage.

New technologies focus on lowering the costs associated with installing insulation by implanting it into the construction of the house. Structural insulated panels are supporting elements of the house and prevent almost all air infiltration. RASTRA, a method where concrete is poured into recycled-polystyrene blocks, provides both insulation and form. Noted for its low density, stabilized cellulose insulation has been gaining a larger share of the market over the last decade, allowing builders to get the same R-values using less cellulose, therefore lowering the cost of materials needed to do the job.

While spending a lot of money on insulation might seem like a large expense, some states give taxpayers credits for improving the energy efficiencies of their homes. Unlike a roof, insulation is designed to last the lifetime of a house, so making the right choice during construction or remodeling can lead to decades of lower energy costs.