SAP Calculations for Extensions
Extensions are a common way to improve and expand your home, but they often raise questions about energy compliance. Melin Energy Consultants provide expert SAP Calculations for extensions, including overglazing and high-light spaces, ensuring your project meets Part L of the Building Regulations while maximising energy efficiency and comfort.
Do All Extensions Require a SAP Calculation?
Not every extension requires a SAP Calculation. Whether one is needed depends largely on the amount of glazing in your design. Building Regulations stipulate that new glazing should not exceed 25% of the floor area of the extension. If this threshold is exceeded, a SAP Calculation will be required to demonstrate compliance.
How SAP Calculations Work for Extensions
Melin Energy Consultants uses a “Notional vs Proposed” approach for extensions that exceed the glazing limit:
Models the existing house with the extension built strictly to Part L standards, using exact U-values and capping glazing at 25%. It sets the benchmark for energy performance and CO₂ emissions.
Reflects the house and extension as actually built, including extra glazing or upgraded insulation, allowing flexibility while ensuring compliance.
Ensures the CO₂ emissions of the Proposed Report do not exceed the Notional Report, highlighting adjustments needed to meet regulations before construction.
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Information Needed for Your Extension SAP
Most extension SAP calculations can be completed via desktop review. Where plans are unavailable, we can arrange a site survey to gather all necessary data. To carry out an accurate SAP Calculation, we require:
Existing and proposed floor plans, elevations, and cross-sections
Confirmation of construction and services specifications
Details of glazing, insulation, and any heating, ventilation, or renewable systems
Benefits of Extension SAP Calculations
Confirms compliance with Part L and energy efficiency standards
Identifies areas for energy performance improvements
Provides EPCs and regulatory documentation
Supports planning applications and building control approval
Ensures high-glazing designs meet sustainability targets
Request Your Extension SAP Calculation
Ensure your extension or overglazed project is fully compliant and energy efficient. Contact Melin Energy Consultants to arrange expert SAP Calculations, providing practical advice and clear results to guide your project from design through completion.