What is heat load, total energy and primary energy?
The maximum heat load describes how much heat is lost and must be supplied in a building at the time of climate extremes to insure indoor comfort. For Chicago, the design load is 0°F. Because a One-Watt-House™ loses its heat much slower in those extremes, temperature lows and peaks are less noticeable. Heat Load is a dynamic measure and expressed in Watts or Btu/hr . Total on-site energy demand includes all fuels & forms of energy supplied: electricity, natural gas, propane, etc. typically over one year and is measured in kWh, Btu, Therm, per conditioned floor area etc. Primary Energy (PE) is the amount of energy the power plant needs to process in order to balance the total on-site energy demand. It includes inefficiencies during generation, distribution and transformation of energy. The total Primary Energy of a building depends largely on the local power supply structure and the Primary Energy conversion factors. The national average Primary Energy conversion factor is about 3.
