The term HSPF / FRSC stands for Heating Seasonal Performance Factor (English) air conditioning This is a very important indicator when you want to use your Air Conditioner to heat your home. The HSPF is actually a ratio or rating of energy efficiency according to their heating performance. The higher the HSPF, the less energy the appliance will consume during the heating season. HSPF = Heating power (in BTU/h) / Appliance consumption (W/h)