the interpolation

At -7°C the heat pump operates in full load to deliver heat to the house. At +2°C and at +7°C the heat pump operates in part load. COP for part load operation is interpolated by using linear interpolation between existing test points. At +2°C the interpolation is made between full load operation and operation at 47% part load, at +7°C the interpolation is made between part load operation at 50% and 57% of the heat pump capacity. At +12°C the required heat load is so small that the heat pump is assumed to cycle on/off. The capacity of this point is calculated by using equation 11 in the standard. The COP for the bivalent point is interpolated from test points in full load operation at +2°C and -7°C