Finance & Net-Zero Energy Terms Energy Terms Explained: R-values and insulation. Electricity and energy. Electricity and power. Heating degree days. Triple-glazed windows. R-Values and windows. R-Values and u-factors. Low-E means low emissivity. Air conditioners, refrigerators and heat pumps. Single-glazed, double-glazed and triple-glazed windows. Finance Terms Explained: Internal rate of return. Net present value. Payback or breakeven period. Net Zero Energy Terms Explained: Zero-carbon footprint and net-zero energy PassivHaus (Passivehouse), PHIUS LEED (Leadership in Energy and Environmental Design) Certification Zero-Energy Ready Home (ZERH) and Home Energy Rating System (HERS) Greenness