The U.S. Department of Energy provides minimum recommended R-values for homes based on climate, heating source, and the space needing insulation, such as attics, basements, or walls (see map below right). Consider exceeding these levels (superinsulating) for maximum energy efficiency. You’ll need to compare the life-cycle savings to your initial insulation budget to figure out the best return for your investment.
If you have a limited budget for insulation, experts recommend insulating your attic or ceiling first. Compared to floors and walls, attics are a major contributor to a home’s heat gain and loss, and bundling up an attic can shave up to 30% from your energy usage. Besides having a large surface area for heat transfer, attics commonly have other conduits for air infiltration, such as light fixtures, plumbing and electrical chases, chimneys, exhaust fans, and ducts. Together, these can account for more heat transfer than the entire flat surface of your attic (see the “Don’t Forget Ducts” sidebar).
Next, insulate walls and floors. In new homes, adequately insulating walls is a no-brainer. In older homes, however, it may be an expensive and difficult task. Get an estimate first, and then do the math to see how long it will take to recoup your investment at a 16% to 20% savings on your heating and cooling. Insulating crawl spaces and underneath floors can save 5% to 15% on heating energy, and is usually an easier job.
Insulation Recommendations for New Wood-Framed Houses
Recommendations for Existing Wood-Framed Houses