The bivalence point is an important concept in the operation of heat pumps. It refers to the outdoor temperature at which a heat pump can no longer extract sufficient heat from the ambient air or the ground due to low temperatures and must rely on an alternative heat source (e.g. electric heater).
The bivalence point is therefore the temperature at which the heating output of the heat pump equals the required heat demand of the building. If the outdoor temperature falls below the bivalence point, the heat pump must switch to an auxiliary heat source to meet the heating demand.