Why EPC Data Is Often Missing, Outdated or Wrong — and What It Means for Buyers and Landlords

The EPC Register — Indispensable But Imperfect

Energy Performance Certificates have been mandatory for residential property sales and new lettings in England and Wales since 2008. The register of issued EPCs, maintained by the Ministry of Housing, Communities and Local Government (MHCLG) and accessible via Find an Energy Certificate at gov.uk, is the primary national dataset for property-level energy efficiency data.

Policymakers, researchers, lenders and property platforms all use EPC data to understand the energy performance of the housing stock, set minimum energy efficiency standards, and plan retrofit programmes. But the register has well-documented quality problems that anyone relying on EPC data — whether as a buyer, landlord, investor or tenant — should understand.

Why EPC Data Is Often Missing

The most common reason for an EPC being absent from the register is that the property has never been sold or let since 2008. EPCs are triggered by a market event — a sale or a new tenancy — not by ownership itself. A property that has been in the same ownership since before 2008 and is not currently being let may have no EPC at all.

Other common causes of missing data:

**Exempt properties:** Certain property types are exempt from EPC requirements under The Energy Performance of Buildings (England and Wales) Regulations 2012. These include listed buildings where compliance with energy efficiency requirements would unacceptably alter their character, standalone buildings with a total useful floor area of under 50m², buildings used for less than four months per year, and industrial sites, workshops and non-residential agricultural buildings. If a property is exempt, it will not appear in the register.

**Registration delays and errors:** EPCs must be lodged on the register by the assessor within five days of issue. In practice, errors do occur, and some EPCs are never lodged or are lodged against a slightly different address that does not match search queries.

**New builds:** New-build properties receive a Predicted Energy Assessment (PEA) before construction completes, which is replaced by a full EPC on completion. In periods of high new-build completions, there can be a lag between physical completion and registration.

Why EPC Data Is Often Outdated

An EPC is valid for ten years. This means a property sold in 2016 with improvements made in 2018 (new boiler, insulation, solar panels) will still show 2016 data if it has not been sold or relet since. The EPC register captures a snapshot at the moment of assessment, not the current state of the property.

The implications are significant. A property may have been upgraded from EPC band E to band C since its last certificate, meaning the current register entry significantly understates its energy performance. Conversely, a property assessed at band C in 2015 with an old boiler now failed may perform worse than the certificate suggests.

For landlords, this creates a compliance risk. The Minimum Energy Efficiency Standards (MEES), introduced under the Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015, require residential private rented properties to achieve EPC band E or above before being let to new tenants (since April 2018) or before renewing or continuing existing tenancies (since April 2020). The government has proposed raising the minimum to band C for new tenancies, though implementation dates have shifted repeatedly.

A landlord relying on an old EPC that no longer reflects the property's actual condition may inadvertently be breaching MEES requirements.

Why EPC Data Is Often Wrong

Even a fresh, recently lodged EPC may not accurately represent a property's energy performance. EPC assessments use a standardised methodology called the Reduced Data Standard Assessment Procedure (RdSAP), which makes several assumptions and estimates rather than measuring actual energy consumption. Common sources of inaccuracy include:

**Assumed rather than measured floor areas:** Assessors use room dimensions that may not precisely match the actual property, particularly for irregular layouts.

**Default assumptions for unknown elements:** If an assessor cannot determine the type or thickness of insulation in a cavity wall, RdSAP assigns a default value. Properties with non-standard construction, extensions or unusual materials are particularly prone to this.

**Assessor variability:** Multiple studies, including research published by the Building Research Establishment (BRE), have found that the same property assessed by different DEA (Domestic Energy Assessor) assessors can receive different EPC ratings. The variation can be significant — sometimes spanning two full bands.

**Improvements not recorded:** Some improvement works (new windows, loft insulation, heat pump installation) are carried out without the property being re-assessed. The EPC will not reflect these changes until a new certificate is commissioned.

What This Means in Practice

For **buyers:** Do not treat an EPC rating as a precise engineering statement about a property's energy performance. Use it as an indicative guide, note the date of the assessment, and consider commissioning a new EPC or a more detailed retrofit assessment (such as a PAS 2035-compliant survey) if energy performance is a significant factor in your decision.

For **landlords:** Check your EPC date and expiry. If the certificate is approaching ten years old or was issued before significant works, commission a new assessment. Confirm that your property meets the current MEES minimum. If it does not, apply for an exemption through the PRS Exemptions Register (if applicable) or plan remediation works.

Property Passport UK displays the most recent EPC data from the register alongside the assessment date, enabling landlords and buyers to see at a glance how fresh the data is and prompting action where the certificate is close to expiry or predates known improvements.