LIGHTING & ELECTRICALS CONTRACTS & LEGALITIES
is Technical Services Manager at Knauf Insulation
With rising energy prices, self-builders need to ensure their dream home is cost effective to run. Bradley Hirst, Technical Services Manager at Knauf Insulation, explains how changes to Building Regulations governing energy efficiency will affect your project and how to get maximum all-round performance from your insulation.
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Approved Document L (Part L) of the Building Regulations governs the energy efficiency of new homes. It was updated in June 2022. Under the changes, new homes must generate 31% less carbon emissions than those built under the previous standards, so check your architect is using the latest software (known as SAP software). Homes must also be tested for airtightness because air leaks between insulation joints allow heat transfer. A Building Regulation England Part L (BREL) report must be produced for new homes. This lists the products specified as well as those used. Crucially, it also includes photographs showing the insulation has been installed correctly. This is because the Government wants to close the gap between how homes perform on paper and how they perform in real life.
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Not necessarily. There’s a one-year transition period, so if you applied for, or obtained, planning permission before 15th June 2022, you can keep your design, provided work starts before 15th June 2023. I BUILDmSEPTEMBERm**
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Compliance must be achieved through fabric efficiency (i.e. insulation) and low-carbon technologies (i.e. heat pumps). Ensure your architect takes a fabric-first approach by ensuring your home is as thermally efficient as possible. This will create the right conditions to get the best performance from any new technologies – and keep your energy bills low.
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Always use a product designed for the application (i.e. loft roll for the loft at ceiling level) because products for different applications perform in different ways. For example, to achieve maximum thermal performance, loft insulation is designed to be installed horizontally in layers to a depth of 400mm or more. But it’s not suitable for external cavity walls because it doesn’t contain water-repellent additives that prevent moisture from penetrating the internal wall and will not deliver the required thermal performance either. The second factor is the ease of correct installation. All insulation products are given a thermal conductivity rating (lambda value). In theory, the lower the lambda value, the better the thermal performance. But in practice, the lambda value may not be achieved on site because
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