Answer by Dale Blundell (Atkins)
A heat pump is functionally the same as an air conditioner, but pumping the heat in the opposite direction. This enables the condenser to operate as the evaporator to take thermal energy from the house, and then be expelled through the evaporator (acting as a condenser). Some heat pumps have a reversing valve allowing bi-modal operation.
A risk of this solution is that by enabling air conditioning where there was none, occupants will start to take advantage of the comfort that it brings, hence increasing electricity consumption
Both GSHPs and ASHPs can be used for heating in the winter and cooling in the summer. If fan coil units, air handling units or chilled beams are used on the distribution system, then they can be utilised for both heating and cooling, otherwise separate distribution systems need to be installed for the heating and cooling.
There are capital savings to be made as only one system needs to be installed and maintained. There are also savings in terms of the plant room space required.
Buildings with separate heating and cooling systems sometimes find themselves in a situation where the two systems are operating at the same time in the same zone and the two systems end up working against each other. This is very wasteful and can have a significant impact on energy bills. Having the heating and cooling systems provided by a single unit helps to prevent this from occurring. Care should be taken when setting up the controls for heat pumps that are capable of providing heating and cooling simultaneously.