EPC rating and sold prices in TW17 (Spelthorne)
In postcode district TW17 (Spelthorne), homes rated EPC C or better sold for 2% less per square metre than D–G homes (median £5,082 vs £5,200, 2,343 sales). Like for like — same size, type, build period and year — homes rated C or better sold for 3.2% more (95% range +1.3% to +5.1%). 2 of 3 sectors with enough sales show a difference distinguishable from zero. Data: HM Land Registry to 30 September 2026, EPC register.
From the raw gap to like-for-like
The homes are not alike: C+ homes here have a median floor area of 83 m² against 90 m² for D–G; both groups are most often built in 1950–1966; 40% of C+ and 69% of D–G sales are detached or semi-detached houses.
| Comparing C+ with D–G homes… | Difference | 95% range |
|---|---|---|
| Raw gap per m² (medians) | −2% | — |
| Whole price, nothing held equal | −5.7% | −9.2% to −2.2% |
| Same floor area | −3.1% | −5.1% to −1.2% |
| + same property type | +6.0% | +4.0% to +8.1% |
| + same build period | +5.3% | +3.2% to +7.4% |
| + same year of sale | +3.2% | +1.3% to +5.1% |
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.
Postcode sectors in TW17
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| TW17 0 | 784 | −1% | +0.9% | −1.6% to +3.5% |
| TW17 8 | 1,054 | −4% | +4.9% ▲ | +2.0% to +8.0% |
| TW17 9 | 505 | −2% | +5.2% ▲ | +1.1% to +9.4% |
▲ green: premium distinguishable from zero; ▼ red: discount; plain: no measurable difference. Small areas have fewer sales, so their 95% ranges are wider.
Sold prices by EPC band in TW17
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 4 | too few |
| B | 154 | £5,092 |
| C | 609 | £5,081 |
| D | 1,082 | £5,215 |
| E | 383 | £5,163 |
| F | 90 | £5,072 |
| G | 21 | £5,577 |
A median is shown when a band has at least 10 sales.
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.