Can the Future Homes and Buildings Standard deliver on its promise?

Launching new building regulations that could slash over £1,000 off a semi-detached home’s bills in the middle of a massive energy price shock is, on the face of it, a smart move. Unfortunately, homebuyers will have to wait until the end of this decade before they can benefit.

This is the promise of the new Future Homes and Buildings Standard (FHBS) which was launched yesterday; the energy regulation that could be the last as all new buildings built to this standard will be net zero carbon ready.

It was first mooted in 2019 with a detailed consultation launched in 2023. For homes, the final version sticks closely to the consultation proposals with the government opting for the greater carbon savings offered by the first of two energy performance options. This includes greater airtightness, wastewater heat recovery and most notably a requirement that 40% of the floor area of a home is covered by PV panels, the main contributor to lower carbon emissions and energy bills.

The FHBS also confirms the phasing out of fossil fuels which means heat pumps are effectively mandated for new homes.

Requiring 40% of the floor area of a home to be fitted with PV panels facing in a southerly direction is a big ask

Although not part of the FHBS, the government also announced yesterday that the ban on plug in solar panels would be lifted and would be available in shops soon. This combined with the recently announced Warm Homes Plan, which offers grants for PV and heat pumps, confirms the government sees PV as a quick and effective solution to high bills and carbon savings rather than expensive and disruptive to install fabric improvements.

Requiring 40% of the floor area of a home to be fitted with PV panels facing in a southerly direction is a big ask. Eleanor Deeley, the managing director of Deeley Group, a medium sized housebuilder reckons that only 40% of new homes could accommodate the full PV requirement. The problem is many homes feature dormer windows or have hipped roofs, which reduce the number panels that can be fitted.

To address this, minimum distances are set out from roof edges and features in the new Approved Document L, housebuilders will need to demonstrate that they are fitting the maximum number of panels within these constraints to building control, if they can’t fit panels that produce at least 720kWh a year then none are required. Buildings over 18m tall are also exempt. This means that many flats and the majority of houses will save less money on their bills.

Mandating batteries would have been a step too far for housebuilders given the considerable additional costs , but the FHBS could have stipulated that a suitable location complete with connections to the consumer unit was identified to make it easier to retrofit 

One answer to this problem is to combine batteries with PV panels so power generated in the daytime can be used at night. Without batteries, the only option is to sell excess electricity generation back to the grid at a lower price than the supply. Batteries also have the benefit of helping to reduce peak demand on the grid, thus mitigating a criticism that the FHBS didn’t include higher fabric standards which would have also reduced demand on our overstretched grid.

Mandating batteries would have been a step too far for housebuilders given the considerable additional costs and the fact this wasn’t mentioned in the consultation, but the FHBS could have stipulated that a suitable location complete with connections to the consumer unit was identified to make it easier to retrofit batteries later.

According to the impact assessment, the additional costs, at 2025 prices of complying with the new requirements compared with 2021 Part L are £5,600 for a semi-detached house. This seems extraordinarily low when a typical PV installation costs over £5,000 and a heat pump is at least another £5,000 more than a gas boiler.

The measures will save homebuyers money, but this doesn’t help the builders who have to front the costs at a time when affordability and viability are under pressure. If homes built to the FHBS can’t be sold for a premium this could lead to fewer housing starts and the government may need to consider ways to mitigate the costs if it wants to continue pursuing its already optimistic 1.5 million new homes target in this parliament.

Another change is the move towards a new compliance tool, the Home Energy Model (HEM). This promises more accurate energy performance predictions than the current Standard Assessment Procedure. But HEM isn’t ready, and to help with the transition when it is launched later this year housebuilders can opt for either tool for the next two years.

The default thermal bridging values are retained in SAP which means builders don’t have the complex task of calculating these for now. The flip side is SAP, which wasn’t designed for calculating the performance of homes with heat pumps, retains a default co-efficient of performance value of 2.5 which means builders could end up specifying more expensive, oversized heat pumps than necessary.

The FHBS takes effect from March 2027 plus there is 12-month transition period so housebuilders can use 2021 Part L until March 2028 providing, they start construction before then. Which is why homes built to the FHBS are unlikely to be available until the end of this decade. Which will be too late to mitigate the impact of this current crisis.

Thomas Lane is Building’s group technical editor