The simplest method of this type of operation, within a ground source capacity, is to pump the source side energy collector through a separate heat exchanger as well as the heat pump where the circuit can used for cooling.
This type of cooling is often referred to as “free cooling” or “passive cooling” on the basis that the unit is operating in heating mode; this is simply an additional circulating pump transferring energy.
Active cooling can also be achieved from the systems plant, where a refrigerant reversing valve swaps the evaporator and the condenser within the unit, so the system is taking energy out of the building, where cooling is required, and transferring heat into the ground source energy circuit, or to atmosphere in the case of an air source unit.
The most efficient method of active cooling is simultaneous with the heating operation of the unit, where the refrigerant is condensing from parts of the building requiring heat and evaporating from the areas requiring cooling.
Simultaneous heating and cooling can provide energy performance ratios, CoP’s or EER’s upwards of 8.