What are the issues with Part L 2020?

05 February 2020

London studio


FCBStudios response to the Part L 2020 consultation.

Part L needs to lead the way on the transitioning to a zero carbon construction industry. To ensure that the buildings built in 2030 are truly net zero carbon, we need to start designing buildings that can operate at this standard before 2025. LETI The current focus of the proposed regulations on CO2 is in treating the symptoms, not the underlying causes. A significant proportion of the proposed savings come not through improvements in the buildings themselves, but the decarbonisation of the grid. Building regulations should be pressing for improved building performance regardless of the grid decarbonisation, which the proposed Part L 2020 standards do not.

Instead, the focus should be on improving energy performance, which will have a consequential improvement on CO2 emissions. Using Energy Use Intensity (EUI) in kWh/m2/yr as a metric will shift the focus to reducing activities that could, and do, produce CO2. Retaining the 'Fabric Energy Efficiency Standard' (FEES) is also key to this objective. Through focusing on the energy use of the buildings rather than CO2, the burden on the already overstretched national grid will be reduced, helping to decarbonise the grid more rapidly.

Studies by LETI have shown that the targets proposed in the Part L 2020 consultation could be achieved using building fabric that would fail the current Part L 2013, simply with the inclusion of a heat pump. We believe that amendments to Part L should focus on reducing energy consumption as a primary objective.

Future Homes Standard

The 75-80% reduction proposed by the Future Homes Standard addresses the regulated aspect of energy usage. However, it does not include the unregulated element, which can easily double the overall energy usage. If this unregulated component is not included, then the predicted reductions will not be achieved in practice, undermining the purpose of Part L. Additionally, most of those percentage reductions are provided by the decarbonisation of the grid so the improvement in building fabric would not be as significant as it ought to be.

A key aspect of the Part L impact is the affordability of energy. This is linked to the demand, not the CO2 emissions and should be reflected in the target.

Although examining reductions in emissions is useful for measuring progress, zero carbon should be the ultimate goal of Part L. Using simple percentage reductions will only ever get us close to zero, but not all the way.


Heat pumps provide the most cost-effective route to low-carbon heat and should be encouraged, particularly over direct electric, which is very expensive to run and considerably less efficient than even a poorly performing heat pump.

Heat networks will have an important part to play in the future of heating, but their true carbon intensity per kWh delivered needs to be independently calculated, including the losses through transmission. Heat networks that support combustion should not be encouraged, as all combustion produces CO2, but also because they will have an impact on air quality.

It should be clear that while electricity is not a low carbon option currently, it is predicted to be so in the near future. The focus should be on reducing energy consumption in the first instance, then choosing the low carbon impact option. Taking this approach, direct electric heating becomes less viable until the heat demand is reduced through improved fabric.

The proposed fabric standards are not demanding enough. New buildings should be aiming to reduce energy consumption as near to zero as practical, through improving the building insulation, reducing air permeability, and improving the form factor.

The Future Homes standard should not be delayed until 2025, but incorporated as soon as possible, with higher standards than those proposed, to ensure that the industry is able to design and build zero carbon buildings by 2025.

Amendment to the Planning and Energy Act

Over 250 councils have declared a climate emergency, and the amendment to the Planning and Energy Act will remove their powers to respond to their specific needs. The government, which has also declared a climate emergency, should be supporting councils in their progress to become net zero carbon.

Through restricting the powers of the local planning authorities, it would send the message that the Part L standards are enough to reach their zero carbon goals, which is it not. By enabling local authorities to increase their targets, it could increase the industry's knowledge and capability of zero carbon buildings far quicker than it would otherwise.

The current London Plan requires a 35% reduction in CO2 emissions, with 10% arising from fabric alone. This has not harmed development in London, and the new Part L requirements would be a step backwards.

It should not be the position of the government to impede those who wish to improve their local environment.

2030 Zero Carbon Targets

To meet the 2030 zero carbon targets, we must be building zero carbon buildings by 2025. In order to make this deadline, the proposed standards must be phased in much sooner. This must be complemented with transparency of performance in-use, similar to the DEC methodology, to ensure that we are delivering the low energy buildings we need. Prior to 2030 we also need to urgently address the issue of embodied energy, which should feature in the 2025 standards at the latest.

Instead of primary energy or CO2, the main metric should energy use intensity (EUI) in kWh/m2/yr, including both regulated and unregulated energy. Through reducing energy use, the industry will be consequently reducing the CO2. This decouples the risk from the grid decarbonisation, which is subject to fluctuations that may not affect the construction industry.

Through measuring energy, it will also empower building owners to understand their energy use, giving them an accurate design benchmark they can use to measure themselves against.

Overall, the proposed 2020 Part L and F Building Regulations do not go far enough. Without ambitious targets, the industry will not be able to meet net zero targets by 2030. Taken as a whole, the proposed regulations could see the industry going backwards, and encouraging the development of less energy-efficient buildings.

Joe Jack Williams and Andy Macintosh

This text is adapted from FCBStudios' full response to the proposed Part L and F Consultation. With thanks to all at LETI and ETUDE for collaboration and research.

Consultation on Parts L and F closes on Friday 8 February 2022.