DEA Minimum Evidence Requirements: A Practical Field Guide

The short version: an auditor should be able to replicate your EPC using nothing but the evidence you leave behind. Not your memory of the property, not a general impression of a “typical” 1930s semi, but the sketch plan, site notes, photographs and documents you actually captured on the day. This guide breaks down the DEA minimum evidence requirements section by section, with practical tips from site that make them easier to hit consistently, whether you are newly qualified or years into practice. It draws directly on the published DEA Minimum Evidence Requirements document.

From 1 October 2026 these minimum evidence standards apply to every inspection, and from November 2026 your lodgement software will ask you to declare that you have met them. We explain what that means in practice in our guide to the new EPC evidence standards.

Why This Matters Beyond the Audit

It is tempting to treat evidence requirements as a box ticking exercise for the audit. In practice, thin evidence is usually the same thing as a thin assessment. If you cannot evidence the loft insulation properly, there is a reasonable chance you did not check it properly either. Building the evidence habit and building assessment accuracy are the same habit.

This is also a minimum list. Additional evidence may be needed depending on the property: an unusual extension, a heat pump with no visible label, a party wall of uncertain construction. Treat the list as a floor, not a ceiling.

Floor Plan and Site Notes

Your sketch plan needs to cover every level, with measurements and area calculations for all building parts, window measurements and orientation, internal room layout, and identification of heat loss and party walls. Keep everything metric, to two decimal places. Window measurements and orientation can go straight into site notes, mobile or paper, rather than onto the sketch itself.

Site notes carry anything mandatory that is not already covered by the floor plan or by photographic or documentary evidence, including the reasoning behind any judgement call. For more on keeping these organised, see our article on managing site notes and records.

Tips from site:

Say whether you measured internally or externally for each building part, and stick to one method for that part.
Write the reason, not just the answer. “Age band from the original windows and the 1983 extension plans” is evidence; “1976 to 1982” on its own is not.
If you use a paper sketch, photograph it before you leave the property so it cannot go missing between the visit and lodgement.
Record anything you could not see or reach, why, and what you did instead. A clear note turns an access problem into a defensible decision.

Photographic Evidence, Section by Section

Photos must be clear, date stamped and geo tagged where possible. A single photo can evidence several elements at once, and photos are only required where they apply to the property being assessed. For general best practice on capturing and organising your images, see our article on photography for EPC assessments.