To achieve an excellent working heat pump system, the right type of heat pump must be chosen and installed with a matching heat distribution system. For this reason, it is important to have reliable information on both the heat pump itself, and how it is influenced by the surrounding system.

Heat pump quality and performance is increasing. One reason for this is the work with standaridisation including calculation as well as performance testing procedures. The work with standardisation has improved continuously since the late 1970s. Despite this the performance of the heat pumps (COP) is often characterised at single operation conditions and at full capacity. These conditions do not always reflect the real performance of heat pumps in practical operation in heating systems. Heat pumps mainly operate intermittently or at reduced capacity, through capacity control, in climatic conditions that differ from the standard rating conditions. It is therefore important to study the seasonal performance factor (SPF) based on a number of operating conditions. The influence of part load or variable capacity on SPF is not fully covered by existing methods for calculation of SPF.

The European Seasonal Energy Efficiency Ratio (ESEER) is calculated from a few operating points and is the same for the whole Europe. Such a method would also be feasible for heating purposes. A method showing the benefits of capacity controlled units is needed to promote more energy efficient heat pump systems/units.

A common SPF method would be important for fair comparison between different types of heat pump systems as well as fair comparison with other competing technologies using fossil fuels. A common SPF method can later be incorporated in different labelling, rating and certification schemes. There is thus a need for an improved transparent and harmonised method for calculation of heat pump system SPF based on repeatability and reliable test data from laboratory measurements.


The calculation method for SPF should cover the following heat pump systems and operating modes:

  • single and multi family buildings
  • heating, cooling and DHW
  • capacity control

The objective is to

  • Establish common calculation methods for SPF using a generalised and transparent approach. The focus is on a fair comparison between different heat pump types, but also for comparison between different competing technologies, such as pellet boilers, gas boilers, ….
  • Establish comprehensive test methods based on further development of existing test standards will be evaluated. The test standards should include test conditions needed for the future SPF calculations.


The Participants shall share the coordinated work necessary to carry out the work required for this Annex. The objectives shall be achieved by the following task-sharing activities:

Task 1 – Survey and evaluation of existing testing methods and calculation methods for SPF

Each participating country complete a spreadsheet to provide 1. Strengths (advantages) and 2. Weaknesses of current test and calculation methods for a number of common system  and product types. Also make an analysis of what’s missing in present methods. The second phase is to provide detail on measurements, test conditions, rating methods, etc. for these current methods and to suggest ways to correct deficiencies of these.

Task 2 – Matrix definition of needs for testing and calculation methods

The definition of a matrix for evaluation of existing testing and calculation methods should contain  a specification of the needs for testing and calculation methods, such as e.g.

  • Measurement requirements (what has to be measured) in existing standards for measurement of combined operation (heating, cooling, DHW) that can be used as input for an SPF calculation
  • Measured test conditions needed from laboratory measurements for calculation of SPF in different regions
  • Measurement requirements (what is measured) in exiting standards for measurement of combined operation (heating, cooling, DHW) that can be used as input for an SPF calculation
  • Measured test conditions in exiting standards

This matrix should be seen as the specification of requirements for developing a testing method that fulfils the annex goals. System boundaries connected to the different system test levels will be developed in this task as well. (System boundaries for unit, heat pump system and building).

Task 3 New calculation method for SPF/ Commonly accepted definitions on how SPF is calculated

Improve existing and/or develop a common transparent calculation method for SPF on a system level based on technical data from laboratory measurements. One important outcome from this part is the need for number of regions, number of building types, number of climate zones etcetera. This may be different for different countries, system types, etc. and that likelihood should be recognized.
Better understanding of how others do their calculations, by understanding the definition of performance metrics is an important component in this task.

Task 4 Identify improvements to existing test procedures

Depending on the outcome in task 3, existing test standards will be further identified, and suggestions for development to cover the needs identified in task 2 will be proposed. Further development of test procedures for capacity control is expected. Other improvements can be new test conditions as well as new test procedures for combined operation with heating and cooling.  The main objective of this task is to suggest improvements in current testing methods by showing how they can be implemented in existing standards.

Task 5 Validation of SPF method

Validation of calculation method against already ongoing or completed field measurements. Improvement of the proposed calculation method if needed. When you do field measurements, bring the right data to be used in computer models. This calls for an action where the data needed from field measurement methods are listed depending on calculation method. Alternately, one unit could be tested under the different standards in use, and the results could be compared, and differences between regions could be identified. Based on these comparisons, guidelines on how comparisons of test values between different regions will be suggested in order to give better understanding.

Task 6 Development of an alternative method to evaluate heat pump performance

The objective with this task is to find ways to make valid comparisons with other heating systems, using performance indices such as carbon footprint and/or primary energy use.

In order to evaluate the heat pump performance in alternative ways, a method will be developed to enable the calculation of  for e.g. the energy savings potential and the CO2 reduction potential from heat pumps, , or the primary energy consumption. Which method is chosen will depend on the needs from the project partners. Independent of the method chosen, the method should include performance for competing heating technologies, e.g. gas or oil. It should also consider carbon emissions from electricity production. The method should only consider space heating and domestic hot water production.

Task 7 Communication to stakeholders

Task 7 deals with clear communication of the outcomes of the Annex to relevant stakeholders. Relevant stakeholders are policy makers, standardisation organisations (ISO, ASHRAE, CEN, and others), and industry. by participants in this annex. Since the work is:

a. level ground investigations, and

b. pre-normative research

The results could be used to harmonise standards and propose improvements in existing standards. Both partners in the Annex already involved in standardisation, and the OA will communicate the results from the Annex, but the formal role to communicate results lie on the OA. A comm¬uni¬cation plan will be set up by the OA for the communication with stakeholders.