Are the energy standards for new homes going backwards?

There has been much coverage in the press and on social media that the proposed changes to the building regulations in England could result in homes that are worse than the current standards. We disagree and have carried out our own investigation.

Following the publication of the Future Homes Standard consultation by the Ministry of Housing Communities and Local Government (MHCLG), one of the more newsworthy proposals was the removal of the Fabric Energy Efficiency Standard (FEES) in the next revision to Part L. FEES was introduced in Part L1A 2013 in order to ensure a fabric first approach to construction and to prevent dwellings with poor build quality being ‘green washed’ through carbon compliance with the use of low and zero carbon technologies.

The Future Homes Standard consultation proposed three mandatory metrics of energy efficiency to be used in Part L 2020. Primary Energy is to be introduced as a result of the Energy Performance of Buildings Directive. Carbon will remain in the form of the Dwelling Emission Rate (DER) and Target Emission Rate (TER). Finally, a third metric known as the ‘Householder Affordability Check’ will be introduced, based on cost. This is to prevent householders from being burdened with high utility bills, particularly where electric heating is used.

There have been suggestions that removal of the FEES standard could see dwellings built to a worse fabric performance standard than currently allowed, particularly where electric heating is used. Elmhurst has modelled a wide range of homes using Design SAP 10 Beta.

Example case

By way of an example, a detached dwelling with an air to water heat pump, the following fabric specification was required to achieve compliance with the DER/TER and FEES standard in Part L 2013 (the current standard);

  • Wall – 0.22 w/m2k
  • Roof and Floor – 0.12 w/m2k
  • Double glazed windows – 1.4 w/m2k
  • Air Tightness – 5 m3/m2/hr @ 50 Pa
  • Accredited Construction Details for thermal bridging

When compared against the proposed Part L 2020 standards whilst the DER/TER standard comfortably complies, the primary energy metric does not meet the Future Homes Fabric (Option 1) standard. Therefore improvements will need to be made to the dwelling to achieve this standard.

Of course to obtain the more demanding ‘Fabric plus Technology’ (option 2) standard, the government’s preferred option, then more extensive improvements need to be made. In this scenario the developer has a choice; either improve the fabric, add some low/zero carbon technologies, or do a bit of both. In our experience a developer is likely to choose fabric improvements over low/zero carbon technologies dues to the lower cost, installation and maintenance.

As result of the removal of FEES, the consultation has proposed a tightening of the limiting fabric ‘back stop’ standards. If we apply the proposed limiting fabric backstops in Part L 2020 then the dwelling will not meet either the option 1 or option 2 on either the primary energy or carbon standards. Again, improvements would need to be made to achieve compliance and we believe this would likely be led by a fabric first approach.

Finally, don’t forget the third proposed compliance metric is based on cost. We don’t yet know what standard the Householder Affordability Check will be set to; we do know the proposal is to be set against the EPC banding so it could for example ask for a new home to be A or B rated. This may result in electrically heated dwellings having to do further improvements compared to current Part L 2013 as the cost of on peak electricity is still around 3 times more expensive than mains gas in SAP 10.

Comment from Elmhurst Technical Director

Stuart Fairlie Elmhurst Technical Director: “We welcome the new proposed regulations, indeed they are long overdue. The clear goal of making our homes more energy efficient is complex, some people want zero carbon, some zero energy, some warmer homes, some all three; all of these are absolutely vital; however, unfortunately, if a drive to use a less carbon intensive fuel, means that that the price is more expensive for the home owner – is this acceptable? The Ministers clearly are looking for a ‘balanced approach’ so that homes reduce all three. We here at Elmhurst believe that we need to push for low energy demand homes as the way forward, as these will use less energy in the first place. However it is clearly worthwhile making sure that people don’t end up in homes that cost them more to run, and produce more carbon emissions, just because the home uses less energy.

We truly believe that compliance using the balanced approach will result in better homes. How far the targets for each are improved is the key question. We would certainly advocate for significant steps through to 2025 to ensure that the home built are indeed energy efficient and don’t need expensive retrofit in the future.

The focus must also shift towards the difference between theoretical design performance, the quality of the construction and the performance in habitation. Elmhurst advocate that we need asset ratings to demonstrate compliance, operation ratings to add the people factors, and ongoing metered data to ensure that he home performs in reality. When we bring these three data pieces together we will be able to state that we are designing, building and living in energy efficient homes.”

Summary: are homes going to be worse for energy efficiency? Our belief is that the answer is no, because the triple lock that all new homes must comply with the carbon, energy and running costs (as well as meet the back stop values). The removal of FEES creates a theoretical step backwards which cannot be replicated in practice.


Elmhurst have modelled many homes using different architypes and main heating fuels. The table below summarises this neatly. This shows a detached home that currently complies with the building regulations.

The home was modelled on Design SAP 10 Beta.

  • Based on L1A 2013 compliant specification;
  • Cavity wall – 0.22 w/m2k , Roof & Floor – 0.12 w/m2k
  • System boiler or air source heat pump
  • Air Tightness – 5 m3/m2/hr @ 50 Pa
  • Double Glazing u-value 1.4 w/m2k
  • Accredited Construction Details
  • Intermittent fans










Detached House








84 B       








88 B








80 C








71 C


  • Dwellings Primary Energy Rating (DPER)
  • Target Primary Energy Rating (TPER)
  • Dwelling Emission Rating (DER)
  • Target Emissions Rating (TER)
  • (1 and 2 are the 2 proposals from government 20% or 31% uplift on current standards)
  • Red = Fail, Green = Pass


To conclude not one home would now pass the new proposed new regulations. All must be made better in terms of the energy efficiency of the building. A home with an electric heat pump may pass the Carbon (DER) compliance, but it needs work to pass both the Energy (DPER) and the EPC rating.

For a link through to Elmhurst Draft response click here

Article published 29th January 2020

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