22nd January, 2021

The Future Homes Standard – Part L1 2021

The long awaited response to the Part L consultation was finally published on 19th January. The FES Group will be running a Technical Advice Session in February to guide you through the changes and look at the implications for the industry. 

The FES Group have reviewed the response from Government on the proposed changes to Part L following the consultation on the proposed Future Homes Standard.
Despite a notable delay due to the COVID-19 pandemic, the response has answered a number of questions and set-in motion the requirements of the interim update to Part L1 2021. It has also left some details yet to be confirmed. The FES Group will continue to provide updates over the coming weeks and months as the SAP10.2 software is developed and released.

The FES Group acknowledge the Government’s intention to implement the interim update in June 2022, with a proposed 12-month transitional agreement which will be applied on a plot-by-plot basis.

The FES Group also acknowledge the Government’s intention to accelerate the consultation on the Future Homes Standard 2025, Which is planned to be implemented in 2024 with a 12-month transitional agreement. It is anticipated that Part L 2021 and SAP10 may only be applicable for a few years.

In regards to the proposal to amend the Planning & Energy Act 2008 to restrict local authorities from setting higher energy efficiency standards than the regulations. This has not been implemented and will be reviewed following the October 2020 consultation on the Planning & Energy Act 2008. While The FES Group feels this is reasonable the concerns with regards to a misunderstanding by local authorities on what reductions are being proposed will continue until better guidance is provided to local authorities when preparing local planning policies.

Part L 2021 Standards for New Homes

The consultation put forward two options: option 1 being a 20% reduction in CO² emissions and option 2 being a 31% reduction in CO² emissions. It was acknowledged within the document that these options would increase build costs but would reduce running costs for the end user and that this would be the first step towards a desired 70-80% reduction by 2025.

The response to the consultation has confirmed the Future Homes Standard will achieve a minimum 75% reduction over current standard with Part L 2021 to implement the proposed option 2, a 31% reduction in emissions over the current regulations. With consideration to the delay caused by the pandemic and additional governments policies introduced within the last year The FES Group had anticipated this choice.

The proven scalable solution for zero carbon heat is a decarbonised electric grid, which as a result puts electric as the anticipated main heating fuel for new dwellings. This is based on the efficiencies provided by using air source heat pumps which are capable of generating 3 times the amount of heat compared to the energy used. The FES Group have undertaken a number of sample calculations and can confirm that the use of air source heat pumps performs well and, in most instances, would provide the only change to build specification needed to gain compliance over the example SAP10.1 software.

It was recognised that the industry has concerns with regards to the available supply chains, skilled personnel and increased pressure on infrastructure and it is stated that the construction industry will be required to implement these changes over the coming years in anticipation of the Future Homes Standard update in 2025.

The consultation had proposed the use of 4 performance metrics over the previous 3 metrics currently used in SAP2012. This included the removal of the Fabric Energy Efficiency metric and the introduction of two new metrics. The Dwelling Primary Energy Rate and the homeowner affordability rating.

It has been confirmed that the Dwelling Primary Energy Rate will be introduced, however the Dwelling Fabric Energy Efficiency standard will remain. The FES Group were slightly surprised by this as the householder affordability standard was intended to make this criteria obsolete, the Dwelling Fabric Energy Efficiency standard had only been in place for one edition of the regulations and solved a problem previously presented in SAP2009 where a fundamentally poor performing dwelling fabric would gain compliance with the use of renewables. While the removal of the Dwelling Fabric Energy Efficiency Standard would not present this issue as significantly as that of the SAP2009 edition it did present some opportunities in further detailed analysis to build dwellings with a fabric performance worse than SAP2013. This is clearly not in line with the intentions of the proposed changes and as a result the Dwelling Fabric Energy Efficiency Standard is to remain.

It has also been confirmed that the householder affordability rating will not be implemented. Again, the FES Group were slightly surprised by this as it was seen as a good way for homeowners to understand the performance of the dwelling. However, it was unclear within the SAP10.1 software and we welcome the reintroduction of the Dwelling Fabric Energy Efficiency standard as an alternative.
The following 4 metrics will be implemented in Part L 2021

  • Limiting fabric u-values.

It has also been confirmed that the limiting factors for fabric u-values are to be improved, however this is over and above the original consultations proposals. In most instances such values are already being achieved. The external wall u-value of 0.26W/m²K however may need consideration for certain projects.

To confirm the proposed limiting u-values for Part L1 2021 are as follows.

  • Floor 0.18 W/m²K
  • External Wall 0.26 W/m²K
  • Party Wall 0.20 W/m²K
  • Roof 0.16 W/m²K
  • Windows 1.60 W/m²K
  • Doors 1.60 W/m²K
  • Rooflight 2.20 W/m²K
  • Air Pressure Test 8.00 m³/m².h

The current SAP appendix K Accredited construction details are being removed and unfortunately are not being formally replaced. However, it is recognised that alternative schemes such as Constructive Details do exist and the intention it to maintain these during the interim Part L 2021 regulations to allow time for more bespoke calculations to be undertaken and adopted.

Finally, The FES Group are pleased to see the confirmed of the updated u-value methodology to BR443 (2019).

Air Tightness

The consultation has confirmed that the methodology will be written by CIBSE in the form of CIBSE TM23 and that air testing will be required on a plot-by-plot basis. It was recognised that at this time only 14% of new build dwellings are assessed on an average air testing basis and due to the already widespread nature of plot-by-plot air testing the implementation of the change will be easily incorporated.

The consultation has also confirmed that the maximum allowable air test to an 8.00m³/m².h will be introduced. However, the proposals to round up all as built Air Testing results within the as built SAP calculation to the nearest 0.5 m³/m².h will not be introduced. The FES Group welcome this as accurate, as tested results represent an accurate input of results within the calculation.

The proposed credit limit on design stage and as built air pressure tests below 3.00 m³/m².h within naturally ventilated dwellings is being introduced, the benefit will only be applied with System 3 or System 4 ventilation which is in line with the guidance given in Approved Document F.

It was also confirmed that an alternative air testing method will be introduced in the form of the Pulse Air Testing Unit. Again, this is welcomed as it provides a different option for air testing beyond the current blower door method.

Compliance, Performance and Providing Information

The consultation proposed the implementation of the BREL document to demonstrate compliance. This is to be introduced and is welcomed, the BREL document is clear and details the various fabric elements within the dwelling, the services installed and the final As Built performance of the dwelling. This document is to be signed by the assessor and the developer and made available to the homeowner.

The proposal to provide photographic evidence will also form part of the pack provided to the homeowner is also to be implemented. This is a significant change, and it has been confirmed that trade operatives will be able to provide these photos. The FES Group are reviewing this requirement further and a specific FES Knowledge email will follow in due course with further details on the photos that will be required.

It was also confirmed that the version of Part L used to prepare the EPC will appear on the final EPC. This will indicate to a homeowner if the dwelling was built to the 2009, 2012 or 2021 edition of the regulations.

It has been confirmed that the BETA SAP10.1 software is to be withdrawn and replaced with the SAP10.2 calculation methodology. This is currently under development, once the BETA SAP10.2 Software has been released The FES Group will continue to assess the impact of the change and offer our initial advice on the implications of the new edition of the regulations.

Report by Paul Bainbridge, Associate Technical Director
For and on behalf of The FES Group
Details of our Technical Advice Session regarding Part L1 2021 will follow shortly.

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