Expert Excessive Glazing Calculations For Part L, Building Regulations
At Forum Energy Consultants, we specialise in precise excessive glazing calculations for your building projects. Our expert team ensures your designs comply with L1A/B Building Regulations, helping you balance large glass areas with energy efficiency. Using advanced software and techniques, we assess the impact of your glazing on the overall energy performance, ensuring compliance without compromising on aesthetics. Whether for new builds or major renovations, trust our experienced team to provide accurate calculations and help you achieve Building Regulation Compliance.
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Part L 2021 Excessive Glazing Calculations
Under Part L2021 Building Regulations for an extension to a dwelling, the basic rule is that the area of windows, roof windows, rooflights, and doors should not exceed 25% of the total floor area of the extension.
​​If this is exceeded, compensating measures should be taken to improve the energy efficiency of the dwelling.
There are two approaches to this:
1) The area - weighted ‘U’ value method
All of the thermal elements in the proposed extension should not exceed the area weighted ‘U’ of a ‘notional extension’ of the same size and shape that is designed to comply.
OR
2) The SAP rating procedure may be used
To calculate and demonstrate that the proposed dwelling and proposed extension fabric efficiency does not exceed that of a notional extension to the dwelling. This is based on an extension that has the correct glazing proportions and correct building fabric thermal elements.
​Either methodology may be used, but it is easier if method (1) can be adopted, as less information about the existing dwelling is required.
Costs for the calculations are based on time charges and vary from project to project depending on their simplicity or complexity.
Get in touch with our team to discuss your project requirements, SAP assessments, or compliance needs.