Heating seasonal performance factor (HSPF) is a term used in the heating and cooling industry. HSPF is specifically used to measure the efficiency of
air source heat pump
An air source heat pump (ASHP) is a type of heat pump that can absorb heat from outside a structure and release it inside using the same vapor-compression refrigeration process and much the same equipment as air conditioners but used in the oppo ...
s.
HSPF is defined as the ratio of heat output (measured in
BTUs) over the heating season to electricity used (measured in
watt-hour
A kilowatt-hour (unit symbol: kW⋅h or kW h; commonly written as kWh) is a unit of energy: one kilowatt of power for one hour. In terms of SI derived units with special names, it equals 3.6 megajoules (MJ). Kilowatt-hours are a common bil ...
s).
It therefore has units of BTU/watt-hr.
The higher the HSPF rating of a unit, the more energy efficient it is. An electrical resistance heater, which is not considered efficient, has an HSPF of 3.41.
Depending on the system, an HSPF ≥ 8 can be considered high efficiency and worthy of a US
Energy Tax An energy tax is a tax that increases the price of energy (Fisher ''et al''., 1996, p. 416). Arguments in favour of energy taxes have included the pursuit of macroeconomic objectives, e.g., fiscal deficit reduction in the 1990s, as well as env ...
Credit.
The HSPF is related to the non-dimensional
Coefficient of Performance
The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...
(COP) for a heat pump, which measures the ratio of heat energy delivered to electrical energy supplied, independently of the units used to measure energy. The HSPF can be converted to a seasonally-averaged COP by converting both the BTU heat output and the electrical input to a common energy unit (e.g.
joule
The joule ( , ; symbol: J) is the unit of energy in the International System of Units (SI). It is equal to the amount of work done when a force of 1 newton displaces a mass through a distance of 1 metre in the direction of the force applied ...
s). Since 1 BTU = 1055.056 J, and 1 watt-hour = 3600 J, the seasonally-averaged COP is given by:
Avg COP = Heat transferred / electrical energy supplied = (HSPF * 1055.056 J/BTU) / (3600 J/watt-hour) = 0.29307111 HSPF.
For instance, a system which delivers an HSPF of 7.7 will transfer 2.25 times as much heat as electricity consumed over a season.
[7.7 times 0.293 is 2.25. Alternatively, 7.7 divided by 3.41 is 2.25] In Europe the term Seasonal Performance Factor ("SPF") is used to mean the same as the average COP over the heating season. A system which transfers 2.25 times as much heat as the electricity consumed is said to have an SPF of 2.25. A well designed ground source heat pump installation should achieve an SPF of 3.5, or over 5 if linked to a solar-assisted thermal bank.
[Thermalbanks and Thermal Energy Storage, http://www.icax.co.uk/Seasonal_Performance_Factor.html]
Example: 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) / (1000) / 15000 (kWh)
: HSPF = 8
See also
*
Coefficient of Performance
The coefficient of performance or COP (sometimes CP or CoP) of a heat pump, refrigerator or air conditioning system is a ratio of useful heating or cooling provided to work (energy) required. Higher COPs equate to higher efficiency, lower energy ( ...
*
Heat Pump
A heat pump is a device that can heat a building (or part of a building) by transferring thermal energy from the outside using a refrigeration cycle. Many heat pumps can also operate in the opposite direction, cooling the building by removing h ...
*
R-value (insulation)
In the context of construction, the R-value is a measure of how well a two-dimensional barrier, such as a layer of insulation, a window or a complete wall or ceiling, resists the conductive flow of heat. R-value is the temperature difference per ...
*
SEER
In the United States, the efficiency of air conditioners is often rated by the seasonal energy efficiency ratio (SEER) which is defined by the Air Conditioning, Heating, and Refrigeration Institute, a trade association, in its 2008 standard AHRI ...
References
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Energy conservation
Heating, ventilation, and air conditioning