People often overestimate the construction quality of their home, not realizing that there are common construction defects and household inefficiencies that affect the performance of every home. New homes are not immune; cosmetic features such as recessed lighting, skylights, columns, and multilevel ceilings are often problem areas. Older homes have often had additions, renovations, and remodels that leave the attic, building envelope, and thermal envelope in worse condition than before.
But don't take our word for it. See what the U.S. Department of Energy, U.S. Environmental Protection Agency and Energy Star say about Home Performance: www.energystar.gov