To: Eddie Hughes MP
Parliamentary Under Secretary of State (Minister for Rough Sleeping and Housing)
Department for Levelling Up, Housing and Communities
2 Marsham Street
cc: Julie James MS, Minister for Climate Change, Welsh Government, Shona Robison MSP, Cabinet Secretary for Social Justice, Housing and Local Government, Scottish Government, Lorna Stimpson, Chief Executive, LABC, Karen Holmes, Registrar, CICAIR
10 March 2022
Calculation of thermal performance (U-values) in AD L
We fully understand the pressing need to reduce the energy demands of buildings in use and see the latest changes to Part L as an important step on that journey. We are writing to you at this time to ask that the methods for calculating U-values for windows and external doors given in the Approved Documents (2021 editions) also allow for those given in the Designated Standard for windows and external doors, namely BS EN 14351‑1, as was the case in previous versions of the Approved Documents (ADs), and in the consultation versions for the current ADs, as this direct reference has been removed from the 2021 editions of the ADs for Part L.
This is very important for our sector, not least because the Designated Standard, BS EN 14351‑1, sets out how the U-values for windows and doors are to be calculated for the purposes of conformity marking (UKCA), as set out in the Annex to this letter. Therefore, a simple addition to the latest Approved Document will prevent confusion and possible additional costs for our members, who are largely SMEs, by having to recalculate or perform multiple calculations for U-values.
We propose the following addition to AD L1 and AD L2 for windows under “U-values” and paragraph 4.2:
- Calculated using the standard window size, depending on the overall product area, and methodology as defined in BS EN 14351‑1.
And for doors, we propose the following addition to AD L1 and AD L2 under “U-values” and paragraph 4.3:
- Calculated using the standard door size, depending on the overall product area, and methodology as defined in BS EN 14351‑1.
We hope you will agree that these important changes to the ADs can be made, and we look forward to working with your department on the next part of this journey in the development of the Future Homes and Future Buildings Standards. This is very important for our industry, as further reductions in U-values will likely require new products and technologies. We need to work with you on the roadmap as soon as possible, so we are ready for 2025. We remain at your disposal.