INSULATION 69 RAISING THE STANDARD?
Jonathan Ducker of Kingspan Insulation GB, discusses the shortcomings of the Future Homes Standard, and why a more ambitious approach is needed for the building fabric in particular to create ‘net zero ready’ homes.
Thermal conductivities down to 0.019 W/mK are achievable with Kooltherm insulation
Detailing guides on common insulation thicknesses and applications assist specifi ers in complying wiith the incoming Future Homes Standard
t the end of 2023, the Government published its consultation on the Future Homes Standard (FHS) in England. This standard was intended to ensure all new homes in England are “net zero ready.” However, the consultation recommendations have been criticised as lacking in ambition – particularly in relation to fabric performance. This is largely unchanged from the existing requirements, which already lag behind those in Scotland and Wales. If applied, this may mean new homes fall short of “net zero ready” performance, could be more expensive to heat and could place additional strain on the National Grid. It could also require the properties to be retrofi tted in the future at considerable extra cost.
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All of these issues could result in reputational damage for housebuilders, despite new homes being fully compliant with the FHS. It should therefore be a priority for everyone within construction to ensure the FHS is fi t for purpose and delivers on its promise.
FHS PROPOSALS Perhaps the most notable changes proposed within the FHS consultation are to the otional Dwelling specifi cation in SAP. This is applied to a theoretical
building of the same dimensions as the proposed home within the energy modelling software to generate the performance targets (for carbon emissions, Primary Energy and the Fabric Energy Effi ciency Standard (FEES)). The latter considers only the U-values, thermal bridging values, thermal mass, internal and solar gains and the airtightness of the property.
The consultation provides two options for the Notional Dwelling, both requiring the use of low carbon heating. Option one retains the current fabric specifi cation (shown in the second column of the table below) but requires air-leakage to be reduced with a mechanical ventilation heat recovery system used to provide ventilation. It also includes use of wastewater heat recovery and photovoltaic (PV) panels covering the equivalent of 40 of the ground oor area. Option two is virtually unchanged from the existing requirements aside from the addition of low carbon heating. As with the existing system, developers would be free to differ from the Notional Dwelling specifi cation on the actual building providing they meet the mandatory performance targets and that no areas of the specifi cation are worse than set limiting values and compulsory
requirements (such as the use of low carbon heating).
The decision to leave the fabric
specifi cation unchanged from the existing version of Part L was unexpected. In the consultation for the 2021 Part L change, the Future Homes Standard in 2025 was suggested as introducing ‘world leading standards of energy effi ciency’ and included a more ambitious indicative specifi cation (shown in the third column of the table on following page). Similarly, the Climate Change Committee had recommended that heating demand in new homes should be limited to 15-20 kwh/m2
/year – similar to the
requirement for Passivhaus properties. Limiting heating demand for new homes is important, not only to lower heating costs for homebuyers, but also to avoid placing unnecessary strain on the National Grid as we switch to electric- based low carbon heating systems, such as heat pumps. This is key, as estimates suggest that the electrifi cation of heat, transport, and industry means demand for electricity is expected to grow fourfold by 2050. If the fabric targets for new homes are not tightened, this may mean they have to be retrofi tted in the future at considerable cost.
A better approach would be to use the
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