EPC rating and sold prices in WD17 (Watford)
In postcode district WD17 (Watford), homes rated EPC C or better sold for 6% less per square metre than D–G homes (median £5,157 vs £5,460, 2,789 sales). Like for like — same size, type, build period and year — homes rated C or better sold for 3.0% less (95% range −5.3% to −0.7%). 0 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 69 m² against 101 m² for D–G; the most common build period is 2012 onwards for C+ and 1930–1949 for D–G; 18% of C+ and 53% of D–G sales are detached or semi-detached houses.
| Comparing C+ with D–G homes… | Difference | 95% range |
|---|---|---|
| Raw gap per m² (medians) | −6% | — |
| Whole price, nothing held equal | −29.9% | −32.9% to −26.9% |
| Same floor area | −8.4% | −10.3% to −6.5% |
| + same property type | +1.3% | −0.7% to +3.3% |
| + same build period | −1.2% | −3.5% to +1.2% |
| + same year of sale | −3.0% | −5.3% to −0.7% |
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 WD17
| Sector | Sales | Raw gap | Like-for-like | 95% range |
|---|---|---|---|---|
| WD17 1 | 320 | +22% | too few | — |
| WD17 2 | 663 | +1% | +1.2% | −4.3% to +7.1% |
| WD17 3 | 500 | −21% | +2.1% | −3.8% to +8.4% |
| WD17 4 | 1,306 | −5% | −2.1% | −4.8% to +0.7% |
▲ 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 WD17
| EPC band (last certificate before sale) | Sales | Median £ per m² |
|---|---|---|
| A | 1 | too few |
| B | 594 | £5,414 |
| C | 770 | £5,000 |
| D | 967 | £5,420 |
| E | 375 | £5,532 |
| F | 68 | £5,660 |
| G | 14 | £4,911 |
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.