Propertoasty EPC Index — Q2 2026: UK home energy efficiency by the numbers

About this Index

The Propertoasty EPC Index is a quarterly snapshot of UK home energy efficiency drawn from the full GOV.UK Energy Performance Certificate register. We ingest the monthly bulk dump (5.4 GB of CSVs covering every certificate lodged 2008–present), deduplicate to the most recent cert per property, and roll up by council area, postcode district, and property archetype.

This Q2 2026 launch report covers five anchor insights. We will rerun the same queries every quarter; the underlying pipeline is open at scripts/epc-bulk/. Cite the headline numbers with the page URL + the May 2026 accessed date.

Insight 1 — UK’s most energy-efficient council area

Tower Hamletsis the UK’s most energy-efficient council area, with a mean SAP score of 75.1 across 111,539 properties. Nine of the ten most-efficient LADs are densely-flatted London boroughs or postwar new towns — Milton Keynes, Salford, Cambridge — where small floor areas favourably weight the SAP calculation. Read the methodology piece at /research/most-efficient-uk-borough-tower-hamlets for the floor-area nuance.

Methodology: Mean of current_energy_efficiencyacross the latest certificate per UPRN (most recent lodgement wins). LADs with <1,000 unique properties excluded to avoid noise. Caveat: SAP penalises larger floor areas; the league table is influenced by the dwelling-size distribution within each council area.

Insight 2 — UK’s least energy-efficient council area

Gwynedd has the lowest mean SAP score in the UK at 57, with potential to lift by 25 points if every property cleared the recommendations on its current EPC. The bottom of the rankings is dominated by rural Wales — Gwynedd, Ceredigion, Anglesey, Powys, Carmarthenshire — plus rural English heritage stock (North Norfolk, West Devon). Common factors: older solid-wall construction, off-mains-gas-grid heating, larger floor areas.

Methodology: Same as Insight 1, opposite end of the ranking. Caveat: rural housing stock with intermittent EPC coverage may be under-represented; the dataset reflects properties that have had a certificate lodged.

Insight 3 — Biggest improver, 2014 → 2024

Burnley has improved fastest in the last decade. The mean SAP of certificates lodged in 2014 was 54.2; for certificates lodged in 2024 the mean was 68.2 — a gain of +14 SAP points. Six of the top ten are Lancashire LADs (Burnley, Sefton, Fylde, West Lancashire, Blackpool, Pendle), suggesting a regional retrofit drive — likely ECO4 + Liverpool City Region Home Upgrade Grant.

Methodology: Mean of current_energy_efficiency across all certificates lodged in 2014 and 2024 separately, per LAD (no UPRN dedup — each lodgement is a fresh cohort observation). Requires ≥500 lodgements in both years. Caveat — selection bias:EPCs are lodged at sale, let, or major upgrade. The 2024 cohort over-represents recently-improved properties; we’re measuring how the active lodgement cohort has changed, not how the underlying housing stock has actually improved.

Insight 4 — National savings potential

UK households could save £4.60 bn per year on heating, hot-water and lighting bills if every property cleared the recommendations on its current EPC — an average of £259 per home per year. The opportunity is unevenly distributed: rural Wales and the Lake District have the biggest per-property savings on the table.

Top 10 per-capita opportunities — £/property/year if EPC recommendations were cleared:

Methodology: Sum of (heating_cost_current − heating_cost_potential) + (hot_water_cost_current − hot_water_cost_potential) + (lighting_cost_current − lighting_cost_potential) across all properties with the latest cert in each LAD. National total = sum across LADs with ≥1,000 samples. Caveats:the £ figures on each EPC are assessor-projected at the prices fixed at lodgement time; 2015-era certs reflect 2015 prices. Real-world 2026 savings are higher in £ terms because energy prices have risen. “Clearing every recommendation” is a theoretical ceiling — not every recommendation is economically sensible (solid-wall insulation often isn’t).

Insight 5 — National waste from inaction

Expressed as waste rather than savings, UK homes are losing £4.60 bn a year to inefficiency that could be addressed with the improvements already recommended on their EPCs. The energy equivalent is 1.89 TWh per year — roughly the annual output of one mid-sized UK gas power station, or 600+ onshore wind turbines worth of avoided generation.

Per-property: 106 kWh/yr of additional energy demand that the recommendations would remove. At the May 2026 Ofgem price cap of 7p/kWh gas and 28p/kWh electricity, this maps to the £259 headline.

Methodology:Inverse framing of Insight 4. Same calculation expressed as “avoidable waste” rather than “potential savings”. Energy figure uses energy_consumption_current − energy_consumption_potential from each cert, summed across the cohort.

Data quality and reproducibility

Source: GOV.UK EPC Register bulk download, file dated 2026-05-01 (published monthly on the 1st). Coverage: 17,763,420 unique properties — approximately 58% of UK domestic dwellings. Properties without any lodged EPC (some long-held owner-occupied stock) are not represented.

The full reproducible pipeline is at scripts/epc-bulk/ — three scripts in sequence: download.ts (fetch the bulk zip), aggregate.ts (deduplicate + roll up), epc-index.ts (produce the insights JSON consumed by this page). End-to-end run on a 2024 MacBook: roughly 30 minutes.

Source licence: Open Government Licence v3.0 (© Crown copyright and database right). Our analytical work is published under CC BY 4.0.

Citation

Cite as: “Propertoasty EPC Index, Q2 2026, propertoasty.com/research/epc-index-2026-q2.” Press + research enquiries via the contact page.