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8 Minute Read • The London Plan

Future Homes Standard: Existing Buildings

The London Plan Part L/Section 6
The London Plan

Future Homes Standard: Existing Buildings


Future Homes Standard: Existing buildings

2022 will introduce a wave of change for new housing developments across England and Wales; making our homes more energy efficient.

But little has been said about how the Future Buildings Standard policy will change the way we design extensions, conversions and major renovations.

It’s true the main focus is on improving the new build sector, but there are also noticeable changes on the cards for when builders upgrade existing houses.

Overheating targets

A new Approved Document for overheating is being introduced. We expect this to cover not only brand new homes, but also dwellings created through barn and office conversions.

This regulation will set new requirements on managing solar gains to reduce the risk of our homes becoming uncomfortably hot in summer months.

We are not expecting this new regulation to cover extensions or renovations.

U-Value targets

Insulation will need to be thicker when rebuilding or extending houses. The maximum allowable U-Values for walls, floors, roofs and windows are all being tightened. Targets in Wales will be stricter than for sites in England.

But the rules on upgrading existing building elements are not changing. Insulation should be included in high heat loss areas, but only when it is viable to do so.

Emission targets

Barn and office conversions don’t currently need to meet a Target Emission Rate, and that isn’t changing.

But it’s a different story for heavily glazed extensions which are currently required to achieve an emission target. In Wales, this target is swapping to the new Primary Energy Rate. The proposal in England is to retain the emission target AND introduce two new targets for compliance – Primary Energy and Fabric Energy. We expect this will push builders towards designing extensions to a much higher fabric standard than today.


It’s all well and good to renovate an existing building, but builders need to make sure the upgrades aren’t too air tight, as a building with restricted air flow is more prone to mould growth and damp.

The new AD F introduces steps to check the natural air flow isn’t detrimentally effected as part of the house renovation. Where major renovation work is proposed, builders will need to seek expert advice from ventilation designers and air tightness testers to make sure the proposed air change rate is sufficient following the works.

EPC results

Building Regulations do not set minimum Energy Performance Certificate ratings for existing homes. But the Minimum Energy Efficiency Act does.

Currently, homes which are F or G rated cannot be rented out until they have been upgraded. This law will soon be extended to cover E rated buildings, and D rated homes – the most common EPC rating currently in England – is expected to fall foul of this law by the end of the decade.

So even if your project meets the Building Regulation targets for overheating risks, U-Values, emissions and air flow rates, you’ll still need to renovate further if the EPC isn’t up to scratch.


The full details of the new regulations are still being ironed out by the UK and Welsh Governments, so look out for future articles from Energist which will confirm when the finalised requirements have been announced, and when they’re due to come into force.

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