EPC rating and sold prices in OX17 (West Northamptonshire)
In postcode district OX17 (West Northamptonshire), homes rated EPC C or better sold for 2% less per square metre than D–G homes (median £3,432 vs £3,503, 2,802 sales). Like for like — same size, type, build period and year — homes rated C or better sold for 2.8% less (95% range −4.8% to −0.8%). 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 116 m² against 102 m² for D–G; the most common build period is 2012 onwards for C+ and before 1900 for D–G; 80% of C+ and 81% 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 | +6.0% | +2.3% to +9.9% |
| Same floor area | −1.8% | −3.7% to +0.3% |
| + same property type | −0.5% | −2.4% to +1.3% |
| + same build period | −0.2% | −2.6% to +2.2% |
| + same year of sale | −2.8% | −4.8% to −0.8% |
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 OX17
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| OX17 1 | 636 | −2% | −5.4% | −11.8% to +1.4% |
| OX17 2 | 1,081 | −4% | −4.2% ▼ | −7.1% to −1.2% |
| OX17 3 | 1,085 | −4% | −3.7% ▼ | −6.7% to −0.6% |
▲ 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 OX17
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 42 | £5,094 |
| B | 404 | £3,351 |
| C | 470 | £3,474 |
| D | 1,054 | £3,530 |
| E | 573 | £3,487 |
| F | 210 | £3,424 |
| G | 49 | £3,373 |
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.