EnergyGauge USA calculates the capacity of equipment required to meet the house's loads according to ACCA Manual J. Our software has been assessed and approved by ACCA. If you are looking at a new home built to current code, or homes built more efficient than code, they are significantly more energy efficient than older homes. They do not need as large of a heating or cooling system. Contractors applying rules of thumb for replacing a system on a 1970s home should throw out such rules when looking at new homes and additions. Efficient homes can be cooled and heated with relatively small systems.

Can a two-ton system in Florida cool a 2400 square foot home? The answer is yes if it is an energy efficient home. In 1998 Florida experienced one of its hottest summers ever. Learn more about the summer of 1998 heat at this link.

During the summer of 1998, FSEC was conducting an experiment of two new Lakeland, FL 2400 square foot homes, each the same floor plan and built by the same builder with the same orientation. One home that just met the code at the time and the other that incorporated numerous energy efficient features including large overhangs, white metal roof and ducts in conditioned space. The control home had a 4-ton unit installed. The sizing calculation indicated about a 21 kBtuh system would work in the energy efficient home and a two-ton unit was installed. So during this peak summer that exceeded the Manual J peak temperatures, how did the systems perform? The house with the two-ton system maintained the temperature at 74 F (Temperature set by home owners). The 4-ton system in the less efficient home failed to maintain 76 F set point, and had the temperature reach almost 80. See this link and figures 54. Conclusion - the two-ton system was more than adequate in meeting the load for a 2400 square-foot highly energy-efficient home.