Overglazed SAP Calculations

Overglazed SAP Calculations from GC Reports

Designing a glazed extension can dramatically improve a space and how it works for the user, however if the glazing area exceeds 25% of the extension’s floor area, a separate calculation must be used to check compliance.

To achieve Building Regulations Part L compliance, it must be proved that the new extension’s overall heat loss/gain performance is no worse than if the extension was built to “Notional” figures, using the minimum acceptable U-value standards.

What We Deliver

At GC Reports, we use Full SAP (Standard Assessment Procedure) calculation methodology to demonstrate compliance for your overglazed extension. This involves assessing the entire property, the existing dwelling plus the proposed extension, to calculate an overall energy performance rating.

• Proposed Dwelling U-Value Calculation: We perform a U-value calculation on the entire property (existing and new elements) to determine the actual energy performance.
• Notional SAP Calculation: We calculate the notional energy performance of the same property, assuming the extension meets the minimum required U-values, to generate a figure which the proposed dwelling must achieve or be better than.
• Compliance Report: We provide a formal report and all necessary data (including the updated Dwelling Emission Rate and Dwelling Primary Energy Rate) to prove that the Actual performance is no worse than the Target performance.

Why Full Overglazed SAP Calculations are Essential for Overglazed Extensions

The Full Overglazed SAP Calculation ensures the whole property is considered when a calculation is being completed, ensuring the calculation is as accurate as possible. Due to this, should changes need to be made to elements to guarantee the project passing, they can be made with accurate results being produced, ensuring compliance.

Consequently, you can rest assured that the report you receive will be precise and exact, ensuring that Building Control will approve the Overglazed SAP Calculation as the legal evidence required to sign the project off under Part L of Building Regulations.