A colleague of ours (we'll call him Bill) once asked our advice on choosing an air conditioner for his newly renovated home. One of our recommendations was "Be sure that the cooling load is calculated and that the air conditioner is sized for that load." That advice proved easier to give than to follow. Only one of the four hvac contractors Bill talked to would submit a sizing calculation (two others just wanted to know the home's square footage). So Bill hired the contractor who did the calculation, and installed a high-efficiency four-ton unit. The local utility gave Bill a rebate for buying efficient equipment. Unfortunately, this is not really a
