EPC rating and sold prices in NP11 (Caerphilly)
In postcode district NP11 (Caerphilly), homes rated EPC C or better sold for 26% more per square metre than D–G homes (median £1,881 vs £1,488, 5,359 sales). Like for like — same size, type, build period and year — homes rated C or better sold for 4.3% more (95% range +2.5% to +6.3%). 2 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 83 m² against 84 m² for D–G; the most common build period is 1950–1966 for C+ and 1900–1929 for D–G; 53% of C+ and 42% of D–G sales are detached or semi-detached houses.
| Comparing C+ with D–G homes… | Difference | 95% range |
|---|---|---|
| Raw gap per m² (medians) | +26% | — |
| Whole price, nothing held equal | +23.2% | +20.3% to +26.2% |
| Same floor area | +24.1% | +21.6% to +26.6% |
| + same property type | +19.8% | +17.6% to +22.0% |
| + same build period | +13.7% | +11.2% to +16.3% |
| + same year of sale | +4.3% | +2.5% to +6.3% |
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 NP11
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| NP11 3 | 554 | +34% | +2.2% | −3.1% to +7.8% |
| NP11 4 | 1,001 | +32% | +0.8% | −3.7% to +5.5% |
| NP11 5 | 814 | +36% | +0.6% | −4.0% to +5.4% |
| NP11 6 | 1,609 | +19% | +3.8% ▲ | +1.3% to +6.4% |
| NP11 7 | 1,381 | +27% | +8.6% ▲ | +4.9% to +12.4% |
▲ 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 NP11
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 4 | too few |
| B | 264 | £2,095 |
| C | 1,384 | £1,847 |
| D | 2,654 | £1,555 |
| E | 876 | £1,330 |
| F | 142 | £1,296 |
| G | 35 | £1,047 |
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.