The built environment's journey to net zero

The built environment currently accounts for at least 40% of the total carbon emissions and huge changes are needed from the sector, to drastically reduce the environmental impact on the planet. This will require all new buildings to be net zero carbon by 2030 and all existing ones by 2050.

The ‘Part L 2020 and Future Homes Standards Review’ will set out the minimum regulatory standards for new builds in England, and the other three UK nations are undertaking similar work.

Arising out of the UK’s 2017 Clean Growth Strategy and Grand Challenge, Part L picks up some key elements:

  • Continued decarbonization of the electricity grid
  • Phasing out of fossil fuels in new homes
  • Future-proofing all new homes for low-carbon heating (e.g. heat pumps, heat storage)
  • A move away from gas cooking
  • Retrofitting existing homes to make them low-carbon and climate-resilient

From that will come a change to regulation and minimum standards. It will be a two stage process leading to a new Future Homes Standard in 2025, but this first update is intended to build in the learnings so far.

Decarbonizing the electricity grid

There is a major shift from gas to electricity as the main source of heating, as electricity becomes much cleaner and renewable energy capacity grows. Regulations will have to respond, future-proofing homes for future generations when gas has run out.

Unintended consequences: overheating homes

From improved insulation to airtightness, current practice in home design is causing more frequent overheating. The negative impacts range from energy demand in air-conditioning to poor sleep quality.

Climate change is exacerbating the problem. If we don’t act, evidence suggests that around 50% of UK homes will run the risk of overheating.

Unintended consequences: ventilation

Another issue to fix is ventilation. There is clear evidence that the ventilation in our homes has become very poor, which has serious health implications – and as we move forward to homes with much better energy performance, we risk under-ventilating still further. So Part F will also address this.

Unintended consequences: the performance gap

The complication arises because building regulations cover only regulated energy such as heating and lighting. There are many other impacts that aren’t regulated, from the number of iPhones being used to the number of people in the home. Actual energy use in homes can vary by 200%, but even when we take those factors into account, research shows there’s another difference that can’t be explained. And that’s what’s behind the performance gap.

It’s possible that the gap happens when a poorer-quality product is substituted for the designer's recommendation. There might also be some areas of SAP that should be improved. But either way, it’s something we must work on so the homes we’re designing will actually perform in practice.

The upcoming changes will include some factors that will help this, and 2025 could see some strict regulations that housebuilders will have to comply with to demonstrate the performance of homes.

Conservation of fuel and power: where are we?

The government consultation begun in 2019 has been interrupted by the pandemic, but it received over 3,000 responses. The feedback was very supportive, particularly from housebuilders. But many said the changes weren’t going far enough or fast enough – a sign that this is all likely to happen quite quickly.

A second piece of work has been delayed by the pandemic, Brexit and the 2019 general election. This includes the overheating work and the work on existing homes. The first phase of this has been consulted on and could be implemented as early as the end of 2021.

A big step in the right direction: the Future Homes Standard. In simple terms, the Future Homes Standard 2025 is a revision to Parts L and F of the building regulations. It requires:

  • The end of fossil fuel use in new builds, including for cooking
  • 75-80% less carbon than one built to the current 2013 regulations

This is a major change – and a big step in the right direction. Every home will have a carbon target and an energy target, and there will be minimum standards for fabric performance and services efficiency. All three will need to come together to achieve a home that’s low carbon and high performance, but also affordable to run.