SCOP = Seasonal Coefficient of Performance (Seasonal COP)
The seasonal average efficiency of heating (or cooling, for that matter) is the most important metric when judging the efficiency of a heat pump. Since a properly sized heat pump rarely runs at full speed, the full speed efficiency is far less important than the overall seasonal average efficiency. That’s why seasonal average efficiency metrics like SEER, IPLV, SCOP, and HSPF have been established, and they matter much more than simple COP or EER.
In the USA, air-to-water heat pumps are rated & certified under AHRI 590/590. As such, there is no HSPF (HSPF is the seasonal average heating COP). Confusingly, HSPF is expressed using imperial number as an “EER” number meaning BTU/W whereas COP is generally expressed Si units such as as W/W. USA air-to-water heat pump manufacturers generally give a heating rating at full speed performance at each outdoor temperature, and may publish a seasonal average COP generated from internal testing or calculated estimates.
However, in Europe, heat pump manufacturers are required to have official third-party heating performance testing and certification including seasonal average heating performance under EN 14825 with officially certified data showing the seasonal average COP, called the SCOP. SCOP is essentially the same as HSPF, in a kW/kW format.
At Chiltrix, while waiting for the USA standards to catch up with the 21st century we submitted the CX35 and CX50 and our new models to European lab testing (TUV, SGS) in order to have the heating performance tested and officially certified to the EN 14825 standard. All Chiltrix heat pumps have been tested to EN 14825. Chiltrix has received an official European SCOP Certification on all heat pumps. Our customers can know for sure what the real heating performance and seasonal average heating performance looks like when officially tested and certified, not generated from internal testing or estimation. The European test conditions for SCOP are highly similar to the US DOE Climate Zone 5A conditions. And it’s the only way to provide officially certified seasonal average heating performance data.
As you might expect from Chiltrix, we did very well scoring the highest rating possible, A+++ on all models, with a SCOP of 5.36 on the CX65 model.
About EN 14825: Unless otherwise stated, all published EN 14825 SCOP values represent the average seasonal heating coefficient performance (COP) in the average climate of Europe which is very similar to USA Climate Zone 5A which has the most similar bin data to the EN 14825 average climate for SCOP testing. USA Zone 5A, characterized as a cold climate, includes cities like Hartford CT, Chicago IL, Manchester NH, and Pittsburgh, PA. The Climate Zone 5A typical meteorological year (TMY) heating bin data aligns closely with the bins established in EN14825 featuring a design temperature of -10°C (14°F) and a total of about 9,092 heating hours across bins starting at -15°C (5°F) with hours increasing gradually (e.g., 89 hours at -15°C (5°F) to 444 hours at 16°C (60°F)). For example, Pittsburgh’s bins, from the National Climatic Data Center and scaled to match ASHRAE 103’s national average of °F-days and 42°F mean temperature, show a comparable distribution, with a mean of 41.6°F after adjustment—making Climate Zone 5A a standard reference for US heating performance calculations equivalent to the European EN 14825 average climate.
About HSPF
As of January 2023, more stringent efficiency terms (HSPF2 and SEER2) were enacted to better reflect airflow resistance due to more realistic duct systems. For example, a unit rated at 15 SEER would be around 14.3 SEER2. Likewise, an 8.8 HSPF would equate to around 7.5 HSPF2 heating efficiency. These changes are really not relevant to most Chiltrix systems, in particular to systems using radiant heating or ductless fan coil units, as they have no ducts and therefore no duct losses.
Source https://www.energy.gov/energysaver/air-source-heat-pumps
HSPF is calculated as Btu/Wh and SCOP is calculated as Wh/Wh so dividing HSPF by 3.412 gives the SCOP and multiplying a SCOP by 3.412 gives an HSPF. This is analogous to converting between EER and COP as explained in ANSI / ASHRAE / IES Standard 90.1-2019. To convert from Energy Efficiency Ratio (EER) to Coefficient of Performance (COP), you divide the EER value by 3.412. This is because COP uses SI units, representing heat output in Watts divided by energy input in Watts, while EER uses imperial units, with heat output in Btu/h and input in Watts. The conversion factor, 3.412, accounts for the relationship between Btu/h and Watts.
To convert SCOP (kW/kW) to HSPF (Btu/kWh) the Chiltrix CX35 SCOP 4.67 would be equivalent to HSPF 15.93. The Chiltrix CX50 SCOP 4.55 would convert to HSPF 15.52. The CX65X SCOP of 5.32 converts to an astonishing HSPF 18.15, as much as twice the average efficiency of many air sourced heat pumps.
ASHRAE Definition for SCOP: The total heating output of a heat pump during its normal annual usage period divided by the total electric energy input during the same period in consistent units (e.g., Watts /Watt).
ASHRAE Definition for HSPF: The total heating output of a heat pump during its normal annual usage period divided by the total electric energy input during the same period, but expressed in non-consistent units (e.g., Btu/Wh)
More information about EN 14825 here.
More information about HSPF here.
See the Official European Certificate
More Reading:
https://www.psehealthyenergy.org/wp-content/uploads/2017/09/HeatPumps.pdf
