Ground Source Heat Pumps
What are they?
A ground source heat pump (GSHP) system uses the ambient temperature of the ground to heat or cool the water used in a heating or air conditioning system. Pipes (known as ‘ground loops’) are installed underground and circulating water is either cooled or heated in them before it is passed through a heat pump. The GSHP can be used in a building for space heating in winter and space cooling in summer. GSHPs run on electricity, and are more efficient than air-cooled refrigenat systems (which they otherwise resemble) due to the more constant temperature of the water from the ground loop.
The ground loops will either be laid horizontally under a very large external area, or vertically under the building, car park or other open space adjacent to the building.
Advantages / Disadvantages
Energy efficient means of heating and cooling a building.
Low maintenance costs.
Expensive to install and disruptive to retrofit because of the requirement to install vertical boreholes or lay pipes horizontally across large areas.
Pumping energy needs to be well managed or this can cancel out benefits
The energy saved using a GSHP system is greatest when the outdoor conditions are extreme. Savings in mild weather are minimal if any. These systems are best suited to inland and high altitude climates in Australia.
The efficiency of the system will be maximised where the system is used for both winter heating and summer cooling.
The heating and cooling provided by a heat pump will reduce gas and electricity consumption and provide a net saving in electricity which will reduce energy bills.
Retrofit / improvement opportunities
GSHP systems are rarely retrofitted because they are expensive to install and because of the disruption caused to the building and the occupants.
All buildings, providing there is sufficient space to install the pipework, either horizontally or vertically. Generally easier to install in open sites than in CBD locations.
Floor plate implications
The GSHP will require periodic servicing and maintenance, comparable with conventional heating and cooling plant.
A GSHP is about the same size as a gas boiler and will be connected to a series of lagged water pipes.
Questions to ask
- Who maintains the heat pump unit and at what cost to the tenants?
- Where is the heat loop?
- Is there a back-up heating / cooling supply during periods of GSHP maintenance?
References to be provided