Did you know that 35 percent of all heat lost in your home occurs through holes, and about 7 percent of your heat is lost through poor attic insulation? So correcting both of those issues can reduce your heating costs by about 40 percent. That’s just by filling the holes in your house and insulating your attic properly.
Start by sealing the gaps in your attic at pipe and duct penetrations with caulk. Add gaskets to electric outlets and switches on exterior walls, and use foam to seal holes where drain pipes penetrate floors and walls. Then check weather stripping at all your doors and windows.
Finally, add insulation in your attic and crawl spaces to bring the R-value up to the minimum standards for your area. You can find these standards at energystar.gov under the “home improvement” tab.