A program called BECAP was created to figure out how much energy HVAC systems use and to find ways to save energy and money. The program was tested on an office building and found that using a variable water volume pumping system was the best way to save energy, with a payback time of 2 years. Another good method was using a total enthalpy heat exchanger, which had a payback time of 4 years. This means these methods can help save energy and money in buildings.