The story is familiar to anyone following the EPC compliance debate. Writing in The Telegraph, a landlord with two decades of experience describes spending thousands on improvements to a Victorian rental property — new heating, new flooring — only to discover the rating had moved from E to D. Still a long way from the Band C required by 2030. The title says it all: I have spent thousands future-proofing my property — I should have done nothing.
It is easy to sympathise. But from a technical perspective, what happened was entirely predictable. The money was not wasted because the improvements were bad. The money was wasted because the improvements did not match what RdSAP actually measures.
What RdSAP measures — and what it does not
The Reduced Data Standard Assessment Procedure (RdSAP) is the methodology behind every EPC issued for existing domestic properties. It calculates a SAP score from a specific set of inputs: wall construction, floor insulation specification, roof insulation depth, window type, heating system, fuel type, and hot water provision.
Notice what is not on that list: tenant comfort, build quality, the feel of a property, or the general level of investment a landlord has made. RdSAP does not know that a landlord cares about their tenants. It knows whether 50mm of rigid insulation was installed below the floor joists.
This is the trap. Landlords spend money improving their properties in ways that genuinely matter to tenants. But those improvements do not move the SAP score if they do not touch the specific inputs the software measures.
The floor insulation problem
In the Telegraph case, the landlord installed floorboards, plyboard, insulated underlay, and wooden flooring. Excellent for comfort and acoustics. Irrelevant to the EPC.
RdSAP has a specific field for floor insulation. It records whether insulation is present and the thickness. Insulated underlay beneath wooden flooring does not meet the specification. The assessor needed to record 50mm of rigid insulation under the floor — a precise technical requirement, not a general standard of being well-insulated.
This is a common and expensive misunderstanding. The recommendations section of the existing EPC would have specified what was needed. Reading it carefully before starting work — and asking the assessor to model the improvement before committing — would have avoided the problem entirely.
The extra heater
The assessor told the landlord they needed one heater to improve the score. The landlord bought two — one for the rating, one for tenant comfort. A reasonable decision in isolation. But the second heater did not move the rating at all.
RdSAP scores heating systems on a combination of efficiency, fuel type, and system type. An additional heater of the same type does not change any of those inputs. The methodology records what type of system is present, not how many units have been installed. The landlord spent money that was entirely invisible to the software.
What should have happened
The sequence should have been:
- Read the existing EPC carefully — specifically the recommendations section and the recorded inputs
- Ask the assessor to model each proposed improvement before any money was spent
- Identify which specific inputs need to change to move the score past 69 (the Band C threshold)
- Implement only those changes, with evidence that they meet the specification RdSAP requires
- Then reassess
This sequence takes longer. It requires more preparation. But it is the only reliable way to spend money on EPC improvements and know in advance what the outcome will be.
The broader lesson
The frustration in the Telegraph piece is understandable. The landlord acted in good faith, spent real money, and got a result that did not match their expectation. But the underlying issue is not that the system is unfair. It is that the system is specific — and specificity requires preparation.
RdSAP is largely deterministic. If you know what the assessor will record, you know what the rating will be before the survey takes place. The methodology does not reward general improvement — it rewards improvement to the right inputs, to the right specification, in the right order.
Victorian properties are genuinely harder to improve than post-war housing. Solid walls, suspended timber floors, and high ceilings all create constraints. But most Victorian properties do have a route to Band C — it just needs to be found before the money is spent, not after.
Getting it right
Understanding the route before committing expenditure is the central argument of EPC Band C by 2030. The book covers how SAP scores are built, which improvements move the rating and by how much, and how to work through the route from any starting point — including the constraints that Victorian properties present.
If you are managing properties and want to understand your options before spending anything, the assessment page explains how we approach it — starting with what the assessor will record, not what feels like an improvement.
The 2030 deadline is real. But the worst outcome is not failing to improve a property — it is spending money on the wrong improvements and finding out too late.