| Measure | Grant | Net cost | Saving / yr | Payback | Grade effect |
|---|---|---|---|---|---|
| Low energy lighting | — | £50 | £17 | 2.9 yrs | +0.5 pts |
| Flat roof insulation | — | £1,500 – £500 | £301 | 3.3 yrs | +9.4 pts |
| Cavity wall insulation | — | £1,500 – £500 | £296 | 3.4 yrs | +9.2 pts · reaches D |
| Warm air unit replacement | — | £2,500 – £500 | £141 | 10.7 yrs | +4.4 pts |
| Double glazing | — | £6,500 – £500 | £143 | 24.4 yrs | +4.5 pts · reaches C |
Grants verified 20 August 2026. Costs are the register’s indicative ranges. Savings are restated at the fuel prices assumed in July 2026. Points per measure are estimated from 19.9 million certificates and rescaled to this home’s own certificate delta; the total is the register’s figure.
Running costs
The full plan saves £898 a year — a 12.7% annual return on £7,050.
Restated at the fuel prices assumed in July 2026. This certificate, assessed in 2017, states £1,208 a year at the prices assumed then. Modelled costs, not a bill.
Sold prices
Estimated today: £389,449 HPI-indexed estimate, not a valuation
St Marks Hill: 451 sales since 1995 · £341,313 average over 10 years
Schools nearby
The schools’ own performance — Progress 8 shows value added, not just raw results.
| School | Phase | Distance | Progress |
|---|---|---|---|
| Lime Tree Primary School | Primary | 0.3 mi | — |
| Maple Infants' School | Primary | 0.3 mi | — |
| St Andrew's and St Mark's CofE Junior School | Primary | 0.3 mi | — |
| The Hollyfield School and Sixth Form Centre | Secondary | under 0.1 mi | Progress 8 +0.28 · above average (2023/24) |
| Tiffin School | Secondary | 1.1 mi | Progress 8 +0.86 · well above average (2023/24) |
| Southborough High School | Secondary | 1.4 mi | Progress 8 +0.29 · above average (2023/24) |
Schools from the DfE register, performance from the KS4 performance tables. Progress 8 is a GCSE measure, so primaries have none. Distance is straight-line from the postcode, not a catchment: admission is decided by the school, not by us.
St Marks Hill
How this home sits against its street.