Heat Pumps
Heating is essential for maintaining comfortable living conditions within the home; achieving a thermal equilibrium is generally taken for granted by many. However a world without modern heating equipment would be somewhat less controlled, resulting in greater vulnerability to colder, harsher external temperatures.
Consideration of a home's heating usage is essential in order to gain environmental and economic benefits, as it is responsible for approximately 80% of a home's annual energy needs. A number of strategies may be implemented to reduce the heating fuel burden, these include:
- Thermostats and Sensors - to control ambient temperature
- Insulation - wall, floor, ceiling.
- Heating appliances - Boilers, Heat Pumps
This section focuses on the increasingly popular Heat Pump, consisting of Air Source and Ground Source Heat Pumps. Heat pumps can provide year round climate control for your home by supplying heat to it in the winter and cooling in the summer. These systems may be used to supplement CHP (Combined Heat and Power) as detailed within CHP section, but depending on the size and type of system installed, they have the potential to be the primary source of heating.
It is important to consider all the benefits and costs of Heat pumps prior to purchase, as although they have lower fuel costs, they have a higher initial capital cost than traditional boilers, and it is worth identifying whether your home is suitable, whereby is there sufficient space capacity, is your energy usage year long round and does it vary substantially. A summary of the benefits and costs of Heat pumps are outlined in Advantages v Disadvantages of Heat Pumps.
Air Source Heat Pumps
Air source heat pumps absorb heat (in the same way that a fridge operates), from outside air during the winter colder periods, able to operate as low as -15C, and conversely extract excess heat during the summer period.
There are two types of Air Source heat pumps; these include the Air to Air heat pump and Air to Water heat pump. Both of which operate on a basis of absorbing heat from external air and transferring this energy, either to the inside air of your home or directly to water in a hydraulic distribution system. The most common system is the Air to Air heat pump.
Costs for an Air Source heat system are approximately £5-10,000 after installation; however this is offset by substantial returns on running costs, providing large financial savings and reduced CO2 output. These systems tend to be used to supplement existing heating appliances, due to their lower output.
Air Source heat pumps are fairly complex systems, consisting of a number of cycles including heating, cooling and defrost cycles. Please read How Air & Ground Source Heat Pumps work for more information.
Ground Source Heat Pumps
Ground Source heat pumps use coiled pipes buried in the garden below the topsoil layer to extract heat from the ground, (illustrated above) which is generally used to warm water for radiators or more suitably, for a under floor heating system.
A common misconception is that they require hot rocks (geothermal energy), this is not true, as they operate on absorbing natural latent heat found anywhere in the ground.
Ground Source heat pumps, similar to Air Source operate best when used in conjunction with a large under flooring heating system, and where energy requirements vary little throughout the day, as they provide relatively lower temperatures than that often provided using conventional boilers.
Although these systems are most costly to install, they provide a sustainable, consistent heating source for approximately 20 years. If installed throughout a home, they are easily adept to act as the primary source of heating.
A number of savings can be made with this system, initial costs vary between £7-13,000, however it is likely that such a system may provide 50% of all heating requirements within the average home.
Are Heat pumps suitable for your home?
Do you have sufficient space? - Both systems take up substantial space, either requiring a large garden area, or space attachable to a wall, which will permit adequate air flow.
Is your home well insulated? - Older properties which have poor thermal retention, I.e. lack insulation, draught proofing are not suitable, due to the relatively low thermal temperatures provided by Heat pumps. Upstairs generally less of a problem, being kept at lower temperatures. Read here for more information on Insulation.
Is your property large enough? - Smaller properties will receive less benefit when using Heat pumps in conjunction with under floor heating, due to lower co efficiencies of performance (CoP).
Is the system intended for a new build? - Cost reductions may be achieved when combining Heat pump installation with other building work.
Further Information
Further information can be found below, from a number of articles in relation to the issue of ASHP and GSHP.