EPC rating and sold prices in NN8 (North Northamptonshire)
In postcode district NN8 (North Northamptonshire), homes rated EPC C or better sold for 23% more per square metre than D–G homes (median £2,797 vs £2,283, 8,984 sales). Like for like — same size, type, build period and year — the difference is −0.1% (95% range −1.2% to +0.9%): the EPC band itself is not reflected in sale prices here. 0 of 5 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 88 m² against 86 m² for D–G; the most common build period is 2012 onwards for C+ and 1950–1966 for D–G; 66% 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) | +23% | — |
| Whole price, nothing held equal | +21.1% | +19.2% to +23.0% |
| Same floor area | +18.6% | +17.2% to +20.0% |
| + same property type | +17.2% | +16.0% to +18.4% |
| + same build period | +5.4% | +4.0% to +6.8% |
| + same year of sale | −0.1% | −1.2% to +0.9% |
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 NN8
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| NN8 1 | 2,388 | +56% | +0.6% | −2.7% to +3.9% |
| NN8 2 | 1,522 | +4% | +0.3% | −1.6% to +2.1% |
| NN8 3 | 1,844 | +19% | 0.0% | −1.9% to +2.0% |
| NN8 4 | 1,329 | +9% | −0.9% | −3.1% to +1.5% |
| NN8 5 | 1,140 | +7% | −0.3% | −2.2% to +1.6% |
▲ 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 NN8
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 149 | £3,131 |
| B | 2,552 | £3,013 |
| C | 2,284 | £2,463 |
| D | 3,104 | £2,359 |
| E | 757 | £2,033 |
| F | 119 | £1,790 |
| G | 19 | £1,295 |
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.