Mike writes from Plainfield, Illinois: "I'm an Architect designing new homes. I've had several clients ask just what kind of energy savings (cost savings) they could expect if we design using 2X6 walls with R19 (or r21) insulation, instead of 2x4 walls with R13 (or R15). Obviously more is better, but many of my clients are looking for a Return on Investment. Also, are there any other studies that show similar increases in attics, basements, etc?"

Answer: It is difficult to give someone accurate numbers on payback because there are so many variables that come into play that impact energy savings. With that said, I did a quick analysis with our GEM program (Global Energy Master) and the annual savings for 2,000 square feet of wall area going from R-13 to R 19 is about $85. We know from experience that increasing your attic insulation from R-19 to R-38 can typically pay for itself in about 5 years. I do not have a copy but there was a study done years ago that showed going from no insulation in a basement to just R-11 can save $400 to $500 per season in cold climates like Chicago. If payback is someone's only reason for increasing their home's energy efficiency then it is unlikely you will convince them to go with more insulation. It is hard to put a price tag on energy efficiency and the benefits to the environment in terms of reduced use of natural resources and carbon emissions. And then there is comfort: In a well design/constructed energy-efficient home, every room will be within three degrees of the set point on the furnace, including bonus rooms. Insulation is not the only thing to detail in designing a new home. In my opinion, more focus should be placed on properly air sealing the home. Air infiltration will bypass the insulation reducing its effectiveness. Good HVAC design also has a big impact.