When asked to describe characteristics of an energy-efficient building, most might list the following: well-insulated walls, a ventilated roof with a thick layer of insulation over the ceiling, quality windows with low-E glass, and a high-efficiency heating and cooling system. Surprisingly, many buildings with these features experience higher than anticipated utility bills, elevated levels of moisture or indoor air pollutants, and premature deterioration caused by moisture accumulation in walls and roofs. Why is this happening and what can be done to avoid these problems?
RULES FOR ENERGY-EFFICIENT BUILDING
RULE #1: Seal all joints in the building shell. It doesn’t make sense to invest in well-insulated walls and ceilings yet do little to block air flow around and through the insulated cavities. Wood-to-wood and drywall-to-wood joints in the exterior shell of a building are not airtight and should be sealed with gaskets, foams, caulks, or air barrier films. The illustration Air