The NHER has jointly developed the new Government-approved system for undertaking an energy survey on an existing dwelling. This system is called Reduced Data SAP – or RDSAP for short.
Work started in 2003 and was split into various phases:
Phase 1 – comparing different data sets and inference rules for undertaking an energy assessment on an existing dwelling and agreeing a standard approach
Phase 2 – testing the agreed approach
Phase 3 – revisions arising from Phase 2; non-standard data collection; integration with HCR data collection; comparison with new build SAPs
Phase 4 – design of the energy performance certificate, and define how to determine the suggested improvements
Phase 5 – define the Quality Assurance requirements
Phase 6a – technical field trials including RDSAP being tested by current practising residential surveyors
Phase 6b – consumer field trials |
Some of these phases are complete, some are still in progress. In this section, you can find out more about the work and download some of the outputs.
What is the Reduced Data SAP (RDSAP) methodology? RDSAP is the new Government-approved standardised system for undertaking an energy survey on an existing dwelling. A full SAP (standard assessment procedure) requires many data items that cannot be seen in a survey (or take too long to collect). RDSAP is an industry-agreed standard set of data items and a standard way of inferring the missing data.
What was used before RDSAP? Before RDSAP existed, a multitude of different proprietary systems were used – which if applied to the same dwelling would each have produced a different answer! The RDSAP system will ensure that householders receive consistent information, to the same high standard.
Will it be used to produce energy performance certificates in England and Wales? RDSAP will be used as the standard methodology to produce energy performance certificates. Home Inspectors - who will produce the Home Condition Report - and Domestic Energy Assessors should be trained on how to assess the energy efficiency of a property using the RDSAP methodology.
The Government has recently confirmed that RDSAP will be the methodology that will be used to produce energy performance certificates in the rented sector.
Will it be used in Scotland and Northern Ireland? The devolved administrations have yet to formally announce the methodology to be used in existing dwellings.
What is RDSAP 2001 and RDSAP 2005? RDSAP 2001 is based on the full SAP 2001 methodology. RDSAP 2005 is based on the full SAP 2005 methodology that is used in England and Wales as part of the revised Part L building regulations from 6 April 2006.
The design of the energy performance certificate to be used within the Home Condition Report in England and Wales can be downloaded here.
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