XeroHome uses advanced building energy simulation tools to estimate how much energy a home will use with various combinations of energy upgrades. It then recommends the combination that works best to achieve Net-Zero Energy. However, in some homes, it may not be possible to achieve Net-Zero Energy. In those cases, XeroHome will recommend energy upgrades that get the home closest to the Net-Zero Energy goal. XeroHome’s energy modeling calculations are also based on best available data about a home from public records, and any input received from the homeowner. The calculations are hence only as accurate as the data available.