Not One Size Fits All

When it comes to decarbonising heat in our homes, there is not one size that fits all. Given that our country’s housing stock is so diverse, different solutions are needed depending on the type of building in question.

That’s why, before embarking on a retrofit programme to install a low carbon heating system, it’s essential to conduct a thorough assessment of a building’s heat loss. This will determine what measures are required to improve the fabric of the building to reduce its heat demand. The calculations will reveal the heat load required, which will in turn inform the choice of heat source. The assessment will also help ensure that all aspects of the heating system will be correctly sized.

Once the health of the building’s fabric and the amount of heat required have been assessed, modern, sustainable technologies such as air and ground source heat pumps should be considered. Air source heat pumps extract heat from surrounding air whilst ground source heat pumps absorb energy derived from underground. This heat is then used to provide hot water and heating to warm up our homes.

If a ground source heat pump is being considered, it is vital to carry out a land search to determine which type is most appropriate. This is because the network of pipes pumping the brine underground, called ground loops can be fitted horizontally or vertically. The type of system you choose depends on the space you have available. Ground arrays are laid horizontally in a shallow trench over a wider surface area whereas a vertical system buries the pipes in a borehole.

If a heat pump is specified, to help save costs, the owners may wish to retain existing infrastructure where possible. For example, if a home has a low level heat loss and currently uses a boiler fuelled by oil or LPG to heat a ‘wet’ system, it may be possible to use the piping and heat emitters – i.e. radiators. But for properties using a ‘dry’ system such as electric storage heaters, piping would need to be installed to carry heated water around the building if a heat pump is specified. If hot water is needed by the residents, hot water cylinders powered by renewable energy sources should also be installed.

Whilst individual homeowners would have their own heat pump, specifiers who are deciding on a low-carbon solution for groups of properties would need to weigh up the cost and benefits of having a centralised or decentralised system.

A centralised system allows for a single heat pump to provide heat and hot water to a number of separate properties. This would cost less to install and maintain, but issues could occur around potential heat loss as it travels from the plant room to the outlying property. With individual properties being separately metered, the system operator may be left with the energy cost shortfall. A decentralised system removes this problem and gives individual control to each property, but this would increase capital costs.

How we will sustainably heat homes in the future is an increasingly important question. But with daily headlines about climate change dangers, we need to reduce our reliance on fossil fuels. Using air and ground source heat pumps to provide heat and hot water our homes can really reduce our carbon footprint – and that’s not a just a load of hot air.