EPC rating and sold prices in NN10 (North Northamptonshire)
In postcode district NN10 (North Northamptonshire), homes rated EPC C or better sold for 7% more per square metre than D–G homes (median £2,543 vs £2,369, 7,978 sales). Like for like — same size, type, build period and year — the difference is −0.1% (95% range −1.2% to +1.0%): the EPC band itself is not reflected in sale prices here. 0 of 4 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 86 m² against 86 m² for D–G; the most common build period is 2012 onwards for C+ and 1900–1929 for D–G; 58% of C+ and 62% of D–G sales are detached or semi-detached houses.
| Comparing C+ with D–G homes… | Difference | 95% range |
|---|---|---|
| Raw gap per m² (medians) | +7% | — |
| Whole price, nothing held equal | +9.0% | +7.1% to +11.0% |
| Same floor area | +7.2% | +5.9% to +8.5% |
| + same property type | +9.8% | +8.7% to +10.9% |
| + same build period | +4.4% | +3.0% to +5.9% |
| + same year of sale | −0.1% | −1.2% to +1.0% |
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 NN10
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| NN10 0 | 3,114 | +10% | +0.3% | −1.4% to +2.0% |
| NN10 6 | 925 | +11% | +0.3% | −2.8% to +3.5% |
| NN10 8 | 1,775 | −2% | +0.1% | −2.1% to +2.4% |
| NN10 9 | 2,164 | +11% | −0.5% | −2.5% to +1.5% |
▲ 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 NN10
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 35 | £2,564 |
| B | 1,240 | £2,492 |
| C | 2,461 | £2,574 |
| D | 3,228 | £2,466 |
| E | 829 | £2,112 |
| F | 154 | £1,874 |
| G | 31 | £1,702 |
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.