Does a C-or-better EPC sell for more in TW18 4 (Spelthorne)?
No measurable EPC premium here. In postcode sector TW18 4 (Spelthorne), comparing like with like — same floor area, property type, build period and year of sale — the difference is +0.2% (95% range −2.0% to +2.5%): the EPC band itself is not reflected in sale prices here. The raw gap is bigger: C+ homes sold for 18% more per square metre than D–G homes (median £5,713 vs £4,852, 1,163 sales 2015–2026), mostly because they are different homes. Across England and Wales the like-for-like figure is +1.2%. Data: HM Land Registry Price Paid to 30 September 2026 matched to the EPC register.
From the raw gap to like-for-like
The homes are not alike: C+ homes here have a median floor area of 65 m² against 78 m² for D–G; the most common build period is 2012 onwards for C+ and 1900–1929 for D–G; 9% of C+ and 38% of D–G sales are detached or semi-detached houses.
| Comparing C+ with D–G homes… | Difference | 95% range |
|---|---|---|
| Raw gap per m² (medians) | +18% | — |
| Whole price, nothing held equal | −2.9% | −6.7% to +1.0% |
| Same floor area | +8.9% | +6.5% to +11.4% |
| + same property type | +10.7% | +8.2% to +13.3% |
| + same build period | +2.3% | +0.1% to +4.6% |
| + same year of sale | +0.2% | −2.0% to +2.5% |
The first row compares median prices per m²; the second compares whole prices; each later row adds one more thing that must be equal, ending with the like-for-like premium (regression of log price; build period from the certificate, 12 bands). The raw gap per m² and the whole-price gap differ because C+ and D–G homes differ in size.
Sold prices by EPC band in TW18 4
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 2 | too few |
| B | 243 | £6,189 |
| C | 357 | £5,223 |
| D | 406 | £4,937 |
| E | 133 | £4,636 |
| F | 16 | £4,751 |
| G | 6 | too few |
A median is shown when a band has at least 10 sales.
C or better vs D–G, by property type
| Type | C+ sales | C+ £/m² | D–G sales | D–G £/m² |
|---|---|---|---|---|
| Detached | 23 | £5,263 | 49 | £5,095 |
| Semi-detached | 33 | £4,762 | 165 | £4,766 |
| Terraced | 96 | £4,928 | 161 | £4,770 |
| Flat / maisonette | 450 | £6,031 | 186 | £5,000 |
Compared with the wider area
| Area | Sales | Like-for-like | 95% range |
|---|---|---|---|
| Sector TW18 4 | 1,163 | +0.2% | −2.0% to +2.5% |
| District TW18 | 4,434 | −0.4% | −1.6% to +0.8% |
| England and Wales | 1,000,000 (sample) | +1.2% | +0.9% to +1.5% |
Average gas use in TW18 4 (2024): meters vs certificates
A rough comparison: the certificate figure is an upper-bound estimate (primary energy including lighting, converted with one factor), so treat the share as an order of magnitude.
| Postcodes with published gas data (5+ meters) | 91 (1,768 meters) |
|---|---|
| Median gas use per meter (median of postcodes) | 10,201 kWh |
| Gas-heated homes with an EPC | 1,376 |
| Energy implied by their certificates (median) | 13,997 kWh |
| Metered gas as a share of the certificate figure (median of 86 postcodes) | 63% (middle half 57%–74%) |
Certificates by band imply: B 4,839 kWh (116 homes) · C 10,600 kWh (618 homes) · D 18,486 kWh (498 homes) · E 30,317 kWh (128 homes) · F 37,819 kWh (11 homes). Across England and Wales, real use is much closer to the certificate for A–C homes than for D–G homes, so the saving an upgrade promises is usually smaller than the certificate suggests.
Certificate energy = primary energy per m² × floor area ÷ 1.13, for homes whose latest certificate shows mains gas heating; it also covers lighting and other uses, so it is an upper bound for gas. DESNZ gas is weather-corrected and covers all meters in the postcode, with or without a certificate.
Can the local grid take heat pumps in TW18 4?
SSEN does not publish spare capacity for street substations, so this is the answer for the wider district fed by the Sidney Road primary substation (33/11 kV), not for your street. Its winter demand headroom for 2027 is 14.0 MVA (lowest of SSEN's scenarios) — room for about 8,250 heat pumps at 1.7 kW each, enough for all 3,807 gas-heated homes with an energy certificate in its supply area.
| Primary substation | Share of the sector's gas homes | Headroom 2027 | Gas homes in its area | Room for heat pumps | Headroom 2030 / 2035 (Holistic Transition) |
|---|---|---|---|---|---|
| Sidney Road | 72% | 14.0 MVA | 3,807 | ≈ 8,250 (100%) | 13.2 / 9.3 MVA |
| Causeway | 15% | 26.1 MVA | 3,617 | ≈ 15,320 (100%) | 25.7 / 22.5 MVA |
| Poyle (upstream constraint) | 14% | 6.8 MVA | 2,373 | ≈ 3,980 (100%) | 6.4 / 5.0 MVA |
Across the sector, about 1,366 of 1,366 gas-heated homes (100%) could switch within the primary substations' 2027 headroom.
Caveat: a primary substation feeds a whole town or several villages. Your street's own substation can be full while the primary has room, and the other way round. Headroom: SSEN Network Scenario Headroom Report 2026, winter demand headroom after contracted connections (MVA ≈ MW). Homes: postcodes whose centre lies inside SSEN's published supply area (19 October 2026). A full primary substation means reinforcement (usually a delay), not a refusal. All areas and the method.
1,163 of 1,413 house and flat sales in the sector since 2015 (82%) were matched to a certificate.
How this is calculated
- Every standard sale (HM Land Registry Price Paid, category A) since January 2015 is matched to the latest energy certificate of the same address (postcode + house number or name + flat) lodged from 10 years before to 3 months after the sale; sales with no certificate or an ambiguous match are left out. Across England and Wales 92% of sales match.
- Price per m² uses the certificate's total floor area (15–1,000 m²).
- Like-for-like premium: regression of the log of price on “C or better”, log floor area, property type, the certificate's build period and the year of sale. The 95% range shows how precise the estimate is; when it includes zero, the data cannot tell the premium apart from none.
Caveats
- The band is the one on the certificate before the sale; certificates are a median 0.8 years old at the sale, but a quarter are over 4 years old and some homes were improved since.
- Condition, garden, parking, views and the exact position within the sector are not known; a premium could hide in them, or they could hide one.
- Individual sales and addresses are not shown.