RdSAP stands for Reduced Data Standard Assessment Procedure. It’s a simplified version of SAP (Standard Assessment Procedure) the UK government’s approved method for assessing the energy performance of existing residential buildings.
Purpose of RDSAP.
RdSAP is used to produce Energy Performance Certificates (EPCs) for existing homes, while full SAP is used for new builds or properties undergoing major conversion.
How It Works
An accredited energy assessor collects key information about the property — such as construction type, insulation, heating systems, windows, and ventilation.
The data is entered into approved RdSAP software, which calculates:
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The home’s energy efficiency rating (A–G)
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Estimated fuel costs
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Potential savings from improvements
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“Reduced Data” Means.
Unlike full SAP, which requires detailed design and material specifications, RdSAP uses default values for many elements (like wall thickness or floor insulation) based on the property’s age, type, and construction. This makes it faster and cheaper to carry out.
Common Uses.
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Producing EPCs for homeowners, landlords, or agents
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Assessing eligibility for schemes like ECO4, GBIS, or Boiler Upgrade Scheme
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Helping surveyors and retrofit assessors plan upgrades