23 Feb, 2024

Future Homes Standard (FHS) is the next iteration of Part L of the Building Regulations, although Parts O and F are also being considered.

The FHS, due to be implemented in 2025, is aiming to eliminate dwellings’ reliance on fossil fuels, instead using low carbon energy sources, such as heat pumps and other renewables. It is currently within consultation with government.

Introducing the Future Homes Standard 2025

With the increase of energy costs and desire to reduce carbon emissions, the UK needs a strategy to reduce energy demand within our homes. The FHS is the next step on the road to zero carbon emissions by 2050. It is looking at 3 main metrics:

Dwelling Emission Rate                                             DER

Dwelling Fabric Energy Efficiency                            DFEE

Primary Energy Rate                                   KW/h/m2 of floor area

TER measures the CO2 emissions, TFEE ensures the fabric is achieving acceptable thermal targets and PER the energy consumption per m2.

There will also be an EPC produced which will give indicative fuel costs, and banding A-G, for the dwelling.

The current National Calculation Method, (NCM) for new build dwellings is SAP, this is being replaced by the Home Energy Model (HEM). Like SAP, the HEM will use a notional dwelling to compare the actual (proposed) dwelling against and hence measure compliance with Part L.

Why Is This New Standard Coming into Place?

FHS supports the government’s “Heat and Buildings Strategy”: the plan to ensure the UK’s nett zero targets are met. 

The built environment in the UK contributes 25% of greenhouse gas emissions. Nett zero target will be met in 2 ways: shifting to low carbon energy sources (and decarbonising the National Grid) and reducing the consumption within dwellings. This will have the added advantage of reducing energy bills and in turn, reduce fuel poverty.

What Does This Mean for Existing Homes?

The FHS, which is changing Building Regulations, will mainly consider new build dwellings.

There will be, as now, a requirement to consider when extending existing dwellings. As now, minimum standards will be required for the new elements of the building.

What Does This Mean for New Home Developers?

As with the 2021 updates to Part L and the introduction of Part O, the FHS will bring new requirements to compliance. Initial investigation, using the available HEM modelling tool, (issued as part of the consultation), suggests that compliance using gas will be very difficult, if not impossible.  Therefore, pushing developers further to electric heating, specifically ASHPs.

In terms of fabric, the proposed improvement to elemental U-values within the 2021 consultation have been dropped, for example, walls within the notional dwelling are still at 0.18, rather than the mooted 0.15. This applies across the board with 2021 values being proposed for FHS. It is deemed the cost of implementing such improvements would be disproportionate to the gain achieved.

Two options which are being proposed though, are around airtightness, with 4m3/m2/hr OR 5m3/m2/hr as options.  There is also, within the notional dwelling, MVHR.

Regulatory Requirements

Submission for the consultation on FHS, is March this year, with the introduction of FHS planned in 2025. This will mean that Building Regulations will be updated and that the FHS will become a regulatory requirement. 

The consultation asks about transitional periods. It is reasonable to expect that there will be some consideration for this, with current regulations on what is deemed a start on site remaining.

Incorporate Renewable Energy Sources

The strategic removal of gas heating in new dwellings has been in developers’ thinking for at least the last 10 years. We, as “UK plc”, must reduce our reliance on fossil fuels to achieve our nett zero ambitions.

Heat pumps and solar PV have become common place and will remain so, moving forward. More airtight dwellings will mean passive mechanical ventilation and heat recover systems will be required.

Building Design & Construction Methods

In addition to the requirements of Part L, Part O is included within the consultation. In many ways, compliance with this, (to minimise the risk of overheating), has been more challenging. This has particularly been the case in dwellings where window opening is restricted because of acoustic and/or air quality considerations.

Part O looks at window areas in relation to floor area. Too higher a ratio then there is a risk of overheating, from solar gain. Then, consideration of opening area is measured. Opening windows will allow purge ventilation, this is particularly relevant in bedrooms, at night.

Obviously, orientation and location of the property plays a part in this calculation too. 

As consideration of this was only introduced into 2021 Regulations, many developers have never designed their dwellings considering these requirements. This has led to initial failure and the need for time consuming DSM (TM59) calculations and redesign.     

Final Thoughts

Stroma Built Environment have looked at the implications within the HEM and offer assistance with all your compliance requirements.

With expertise across Energy, Acoustics and Air Quality, we can work with you to assist with compliance giving you visibility of options to help with optioneering, hence find the best solution for you.