The interim update to Part L of the Building Regulations, due to be finalised in December of this year and come into force in June 2022, has put an emphasis on adopting electric heating systems over the existing fossil-fuel dominated heating systems currently found in the majority of buildings in the UK. How have the changes to Part L emphasised the use of electric heating systems (heat pumps), and why is this approach being taken?
Compliance with Part L of the Building Regulations has, since 2012, been based on two metrics defined by the “notional building”, the Target Emission Rate (TER) and the Target Fabric Energy Efficiency (TFEE) rate. Essentially the actual dwelling has had to equal or better these targets, set based on a standardised specification and details from the actual dwelling.
Alterations to the notional building in the interim update to Part L will result in both of these compliance metrics being more difficult to comply with. This update will also see an update to the emission factors associated with different fuel types, which have not been changed since the last Part L updated in 2012. The biggest beneficiary of this update to the emission factors will be grid electricity, which has dropped greatly from 0.519 kgCO2e per kWh to 0.136 kgCO2e per kWh, reflecting the ongoing decarbonisation of the electricity grid thanks to an increase in renewable sources and decreasing use of coal over this period. The change in emissions for a building with an electric heating system can be illustrated simply using an example building with a 10,000 kWh energy demand:
Current Part L: 10,000 x 0.519 = 5,190 kgCO2e
Interim Part L update: 10,000 x 0.136 = 1,360 kgCO2e
Electric heating systems are now a viable method to heat a building in terms of the emissions they produce. Achieving compliance with the TER will be possible, given that the notional building is heated on mains gas, and grid electricity now has a lower emission factor than mains gas (0.210 kgCO2e per kWh for mains gas). This is essentially pushing for heat pumps, which are expected to be the primary heating technology for new homes under the Future Homes Standard. This change in emissions in particular intends to make heat pumps a viable method of heating a building, as the outdated emission factors would not allow for it. Heat pumps which work best in highly-insulated buildings (which the interim update to Part L will also result in) in both terms of their efficiency and their running costs. Grid electricity may now have a lower carbon content, but the material impact that this push towards electric heating systems will have on homeowners, particularly on the costs and performance, must be carefully considered if they are to be widely accepted.
Due to the changes to the notional building, buildings which choose to install a traditional mains gas boiler will have to have renewable technologies installed in order to meet the TER, as the notional building will have these as standard.
The UK has committed to reaching net zero carbon by 2050, and a major part of this will be in improving the energy efficiency of both existing and new homes. Phasing out the use of fossil fuels and replacing them with electrically-based heating systems will reduce the carbon emissions produced from heating our buildings. The ongoing decarbonisation of the electric grid is predicted to continue, meaning that the carbon content of each kWh of electricity will (ideally) keep coming down in the future. As a result, it is argued that it makes sense to encourage the use of electricity over traditional fossil fuels, given that it can be generated by renewable sources.
With heat pumps being envisaged as the method of heating for homes built to the Future Homes Standard, naturally wider industry has raised concerns over ensuring the supply of heat pumps, and the qualified professionals to install and maintain them will cover the demand. As with all technologies, the suitability, positives and negatives should always be assessed, such as the higher cost a unit of electricity has when compared to the cost of mains gas. The improvement to the fabric requirements should mitigate some of the additional cost for homeowners, as homes under the new regulations should have a reduced demand for heating, especially when compared to the existing housing stock. Although heat pumps are envisaged as the heating system for homes built to the Future Homes Standard, it is crucial that new innovative technologies which could help to reduce our reliance on fossil fuels are encouraged, such as hydrogen boilers. Innovation is seen as a vital part to the governments drive to net zero carbon emissions by 2050, and the regulations must be kept up to date to reflect any changes we may see.
Article published 28/07/21