Why is Tower Hamlets number 1 on the UK EPC league?

Two reasons, in roughly equal weight. First, methodology: the SAP scoring algorithm penalises larger floor areas — a 50 m² flat with the same fabric quality as a 150 m² house scores higher. Tower Hamlets has the densest flat stock of any UK council area. Second, fabric: a large share of Tower Hamlets stock is post-2012 Part L compliant new-build flats (Wood Wharf, Canary Wharf, Limehouse), which are genuinely well-insulated, well-glazed, and increasingly heat-pump-ready. The combined effect: a mean SAP of 75.1, ahead of every other UK council area in our dataset.

Does this mean Tower Hamlets homes have the lowest bills?

Not necessarily. SAP is an efficiency metric (kWh per m² per year normalised by fuel type), not a bill estimate. A small efficient flat does have a low absolute bill, but on a per-m² basis Tower Hamlets isn't dramatically ahead. The 2026 EPC data shows Tower Hamlets median heating cost is around £540/yr — lower than the UK median £680/yr, but rural London suburbs and well-insulated commuter towns in the south-east are comparable. The SAP league table flatters dense flat stock more than the absolute-£ league does.

What does the top-10 list look like?

The top 10 in the May 2026 EPC Index: Tower Hamlets (SAP 75.1), Milton Keynes (72.4), Salford (71.7), Southwark (71.5), Newham (71.5), City of London (71.5), Cambridge (71.3), Hackney (71.2), Dartford (71.2), Eastleigh (71.2). Five London boroughs (Tower Hamlets, Southwark, Newham, City of London, Hackney), three south/east-of-England flat-heavy LADs (Milton Keynes, Cambridge, Dartford), Salford as the only northern entry (dominated by Salford Quays new-build flats), and Eastleigh in Hampshire.

Is SAP a fair efficiency metric?

It's a useful metric for comparing properties of similar type, but it has known biases: it penalises larger floor areas (a 200 m² Victorian terrace scoring SAP 60 might be physically more efficient per kWh delivered than a 60 m² flat scoring SAP 75), and it normalises by floor area in a way that doesn't reflect actual usage patterns. For league tables that try to identify 'best housing stock', SAP is the published metric but interpreting it requires the floor-area context. Our forthcoming Affordability Index publishes per-m² heating cost figures that adjust for this.

What about Scotland and Northern Ireland?

The Scottish EPC register is administered separately and uses a different bulk-release schedule, so it's not in this Index run. Northern Ireland uses a different scheme entirely. This Index covers England and Wales only — about 88% of UK domestic stock by dwelling count. We'll add Scotland to future quarterly Index reports once their bulk data pipeline is set up.

Tower Hamlets is the UK's most energy-efficient borough (EPC Index)

The headline

Across the 111,539 unique properties in Tower Hamlets that have a current EPC lodged on the GOV.UK register, the mean Standard Assessment Procedure (SAP) score is 75.1. That puts Tower Hamlets at the top of the UK’s energy-efficiency league — ahead of every other council area with comparable data.

For context: the UK mean SAP across all 317 qualifying LADs is around 67. A SAP of 75 corresponds to band C on the 7-step A–G EPC scale. Band C is roughly the threshold the UK government has used in successive policy proposals for “rented properties must reach by [year]” — so Tower Hamlets is, on average, already past the political target line.

Top 10 — UK’s most efficient council areas

Rank	Council area	Mean SAP	Sample	Uplift potential
1	Tower Hamlets	75.1	111,539	+4.9
2	Milton Keynes	72.4	88,670	+12.1
3	Salford	71.7	103,501	+10.5
4	Southwark	71.5	95,182	+7.9
5	Newham	71.5	102,472	+9.3
6	City of London	71.5	4,943	+5.9
7	Cambridge	71.3	41,453	+10.9
8	Hackney	71.2	79,001	+7.7
9	Dartford	71.2	34,791	+12.7
10	Eastleigh	71.2	40,013	+12.2

Why floor area matters

The SAP calculation expresses energy use as kWh/m²/year normalised by fuel type. Smaller properties have lower absolute heat demand but the per-m² calculation favours them because heating bills scale sub-linearly with floor area — a 50 m² flat shares walls with neighbours, has less external surface area per m² of floor, and loses heat proportionally more slowly than a detached house of equivalent fabric quality.

Tower Hamlets has the highest flat density of any UK council area in the EPC dataset — roughly 78% of its domestic stock is flats (vs ~22% nationally). Median floor area in Tower Hamlets EPCs: 55 m². Median UK floor area: ~80 m². That 25 m² gap accounts for roughly half of Tower Hamlets’ lead at the top of the SAP league.

The fabric story is also real

The other half of Tower Hamlets’ lead is genuine fabric quality. The borough has had three significant new- build waves in the EPC era:

1996–2008: early Canary Wharf residential (Cascades, Aspen Way, South Quay Plaza). Built to 2000s Building Regs — band C/D typical.
2010–2018: Wood Wharf phase 1, Royal Docks adjacent (technically Newham), Limehouse infill. Built to Part L 2010/2013 — band B common.
2019–2026: Wood Wharf phase 2, Westferry Road redevelopments, Bishopsgate Goodsyard adjacency. Built to Part L 2021 or Future Homes Standard scaffolding — band B/A common.

Combined effect: a large fraction of Tower Hamlets stock was built in the post-2013 EPC-improvement window when UK Building Regs tightened materially. Even with floor area adjusted out, Tower Hamlets’ mean fabric quality is ahead of the UK median.

What this means for homeowners

If you live in Tower Hamlets and your property is post-2010 construction, your EPC is probably already band C or better. The Boiler Upgrade Scheme grant for heat pumps requires loft and cavity insulation recommendations to be cleared on your current EPC — those recommendations rarely apply to post-2010 stock, so most Tower Hamlets owners are immediately BUS-eligible.

The 4.9-point uplift potential is the lowest of any LAD in the top 50 — i.e. Tower Hamlets is closest to its potential already. The bigger opportunity in this borough is electrification (heat pumps replacing existing electric resistance or older gas systems) rather than fabric retrofit.

Methodology + reproducibility

Mean of current_energy_efficiencyacross the most recent certificate per UPRN (one cert per property). LADs with <1,000 unique properties excluded. Source: GOV.UK EPC Register bulk dump 2026-05-01, 17.8 M unique properties.

Full reproducible pipeline: scripts/epc-bulk/. Re-run quarterly with the latest GOV.UK monthly bulk download.

Cite as: “Propertoasty EPC Index, May 2026 (propertoasty.com/research/most-efficient-uk-borough-tower-hamlets).”

EPC aggregate data contains public sector information licensed under the Open Government Licence v3.0 (© Crown copyright and database right).

Tower Hamlets is the UK's most energy-efficient borough — and floor area is why