Enter the total heat output and the electricity used into the calculator to determine the HSFP.

HSFP Formula

The following formula is used to calculate a heating seasonal performance factor (HSFP).


  • Where HSFP is the heating seaonsal performance factor (BTU/watt-hr)
  • HO is the total heat output over the season (BTU)
  • EU is the total electricity used (Watt-hr)

To calculate HSFP divide the total heat output over the seasons by the total electricity used for the season.

What is HSFP?


HSFP, short for heating seasonal performance factor, is a measure of the efficiency of air-source heat pumps and is a ratio of the heat output to electricity use.

How to calculate HSFP?

Example Problem:

The following example outlines how to calculate HSFP.

First, determine the total heat output for the seasons. For this example, the heat pump generated an output of 100,000 BTUs.

Next, determine the electricity use during the same seasons. In this case, the electricity usage was 25,000 Watt-hours.

Finally, calculate the HSFP using the formula above:


HSFP = 100000 / 25000

HSFP = 4