EPC rating and sold prices in SA18 (Carmarthenshire)
In postcode district SA18 (Carmarthenshire), homes rated EPC C or better sold for 26% more per square metre than D–G homes (median £1,779 vs £1,415, 4,479 sales). Like for like — same size, type, build period and year — homes rated C or better sold for 6.8% more (95% range +4.4% to +9.3%). 3 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 99 m² against 96 m² for D–G; the most common build period is 2012 onwards for C+ and 1900–1929 for D–G; 83% of C+ and 80% 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 | +33.4% | +29.5% to +37.5% |
| Same floor area | +28.5% | +25.6% to +31.5% |
| + same property type | +23.2% | +20.7% to +25.8% |
| + same build period | +12.6% | +9.3% to +16.0% |
| + same year of sale | +6.8% | +4.4% to +9.3% |
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 SA18
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| SA18 1 | 1,272 | +26% | +7.8% ▲ | +2.7% to +13.2% |
| SA18 2 | 1,532 | +22% | +7.1% ▲ | +2.9% to +11.6% |
| SA18 3 | 1,675 | +20% | +5.3% ▲ | +2.2% to +8.5% |
▲ 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 SA18
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 22 | £2,417 |
| B | 226 | £1,739 |
| C | 932 | £1,781 |
| D | 1,854 | £1,496 |
| E | 1,030 | £1,340 |
| F | 341 | £1,250 |
| G | 74 | £1,213 |
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.