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The Reduced Data Standard Assessment Procedure (RdSAP) is the standardized methodology for evaluating the energy performance of the UK’s existing housing inventory.
First introduced in the early 2000s, RdSAP enabled national rollout of Energy Performance Certificates (EPCs) from 2007 onwards. EPCs benchmark home efficiency on an A-G scale, where A denotes exceptional performance and G extremely poor.
With comprehensive architectural plans often unavailable, RdSAP utilizes default values and on-site data gathering by Domestic Energy Assessors (DEAs) to generate certificate ratings.
EPCs – an ongoing crisis
In January 2023, a high-profile Times exposé deemed Britain’s EPC regime a “national scandal” – triggering urgent calls for reform. Analysis revealed that while top-tier A and B certificates slightly downplay energy needs, lower bands commonly overstate usage substantially – rendering them “misleading.”
Multiple academics corroborated these findings in the following months, lamenting “shocking” systematic EPC inaccuracies evident. Prominent energy scientists went further, stating that many certificates now remain “worthless” given the yawning gulf between ratings and reality.
With public faith plummeting as scrutiny builds, experts caution that EPCs risk becoming mere “pieces of paper” unless the government confronts deep flaws ingrained in the assessment process. Accurate home energy profiling remains critical for Net Zero.
RDSAP10: An overdue update to the rating methodology
Responding to rising criticism, the Building Research Establishment (BRE) unveiled the next iteration of the official rating methodology – RdSAP10 – in August 2023. Slated for full integration from summer 2024, it constitutes the first wholesale update to the framework in over 15 years.
Among other notable modifications, SAP assessors highlighted how RdSAP10 includes:
Bespoke window measurements, abandoning generic defaults used in previous methodologies
Detailed construction details of rooms in roofs, such as bedrooms and bathrooms in the attic space
Preference to air source heat pump heating systems, instead of the traditional oil, or gas, boilers.
By demanding bespoke property data capture, BRE intends revised certificates to reflect real-world consumption patterns better. But can an upgraded methodology alone resolve the issue of misleading energy ratings?
Assessor competency shortfalls undermine credibility
While previous methodological constraints contributed, many frontline DEAs feel underlying assessor competency gaps now drive accuracy erosion. Alex Papaconstantinou, founder of a nationwide SAP Calculations agency epc4less.com, argues even the most robust appraisal framework remains only as reliable as the aptitude of assessors wielding it.
Previously, extensive classroom learning was supplemented by on-the-job mentoring for DEAs. This holistic training approach efficiently integrated fundamental concepts like building performance, construction types, and system contexts.
In contrast, today’s pervasive rapid 3-day Zoom courses prioritize speed over competency building. People from all backgrounds now enter the domestic energy rating industry, often lacking even introductory construction or engineering knowledge.
Consequently, new energy rating assessors regularly need help to accurately identify basic aspects like wall types, insulation specifications, heat sources, and metering setups.
While an important advancement, many DEAs caution RDSAP10 alone cannot resolve such deep-rooted capability issues now ingrained across the existing workforce. Even the most robust energy appraisal methodologies risk being undermined by patchy, inconsistent assessor training.
Targeted training is vital to restore integrity
Enhancing rating integrity relies not solely on upgraded methodologies but also on assessors’ ability to interpret these appropriately when assessing a home based on sound technical grounding.
To truly leverage RdSAP10’s potential, leaders in the UK’s domestic energy assessment must implement more selective assessor recruitment policies in tandem with specialized, aptitude-aligned capability building.
Reversing the decline in public EPC trust demands policies that confront the current competence deficit head-on. Prioritizing rigorous, in-depth energy assessor skills development remains the foremost remedy to safeguard integrity amid the evolving Net Zero landscape.
