Instead of basing the energy performance ratings on old assumptions like mentioned in the article "For example, the current estimate of hot water use per household — 64.3 gallons a day — was set more than two decades ago, when the composition of households was in many cases much different from today’s."
These energy performance ratings (like hot water boiler efficiency) and other variables (64.3 gpd hot water usage mentioned in the article) have to be updated as new data becomes available. Updating these numbers with not only with the lab testing results but also with data from the field (users) will help us to quantitatively understand the energy consumption and perfomance rating for a particular equipment. These estimates can then be used by the consumers to calculate the energy savings that they expect from upgrading their equipment.
