What is HSPF? You have probably stumble in this heating and air acronym when charged to select equipment for heating and air conditioning.
Let’s get started by quoting from Wikipedia:
HSPF (Heating Seasonal Performance Factor) is a term used in the heating and cooling industry. HSPF is specifically used to measure the efficiency of air source heat pumps.
The efficiency of air conditioners are often rated by the Heating Seasonal Performance Factor (HSPF) as defined by the Air Conditioning, Heating, and Refrigeration Institute in its standard 210/240 Performance Rating of Unitary Air-Conditioning and Air-Source Heat Pump Equipment.
The higher the HSPF rating of a unit, the more energy efficient it is. HSPF is a ratio of BTU heat output over the heating season to watt-hours of electricity used. It has units of BTU/watt-hr.
Depending on the system, an HSPF ≥ 8 can be considered high efficiency and worthy of a US Energy Tax Credit.
So, in contrary to the SEER (Seasonal Energy Efficiency Ratio, see our March blog) which is used for air conditioning units, HSPF is used for Heat Pumps, correctly for air source heat pumps. And it is again a ratio like the SEER, but this time for the heating season: BTU heat output divided by by the watt-hours during the complete heating season.
Therefore, the higher the HSPF the more energy efficient is the heat pump.
Now an example with real numbers, again quoted from Wikipedia for a heat pump HSPF (Heating Season Performance Factor:
For a heat pump delivering 120,000,000 Btu during the season when consuming 15,000 kWh the HSPF can be calculated as
HSPF = 120000000 (Btu) / (15000 (kWh) x1000) = HSPF = 8
From this formula we again see that higher HSPF results from using less electric energy.
When selecting heat pump equipment for heating, higher HSPF identifies a more energy efficient heat pump. And since heat pumps are designed to reverse the flow of heat to serve as air conditioning in summer, heat pumps are also specified by a SEER value. And here again higher SEER signifies better efficiency.