The outdoor

The outdoor climate follows the climate of the year.  The calculation models use the same temperature climate when calculating SPF for the ground source heat pumps. The climate corresponds to a European average climate, Strasbourg, with the coldest temperature of - 10°C.
The field measurements of the ground source heat pumps are carried out in Germany. The heat pumps installations used for the SPF calculations are spread over the country, from the Hamburg area in the north to Stuttgart in the south. In the calculation models the average climate is chosen as the climate mostly corresponding to the German.
The air to air heat pump installation is made in a climate that is similar to the “colder” climate. Therefore the colder climate is used in the calculation models when calculating SPF for the air to air heat pump.