greenhomesums
EPC D → C upgrade for EPC D flat → C
D-band flats are often stuck because of electric heating, not fabric — a heat pump swap is frequently the best (and only) route to C.
Upgrade measure stack
Cheapest-first ordering — calculator stops adding measures once the gap to C closes.
| Measure | Cost | SAP uplift |
|---|---|---|
| Loft insulation top-up to 270mm | £450 | +2.0 |
| Full LED lighting retrofit | £250 | +1.0 |
| Upgrade to modern double glazing | £6500 | +4.0 |
| Total | £7200 | to band D |
What's specific about this archetype
Flats score low mainly on heating-fuel carbon intensity, not fabric. A gas-fired communal system scores better than night-rate electric. For owner-occupiers, an air-source heat pump is BUS-grant-eligible — but approval in a flat block depends heavily on where the external unit can go. LED + controls + insulated hot water cylinder are the obvious starting points.
Model your exact property
The figures above use a reference archetype. Your real floor area, mortgage balance, current energy bill and exact current band will shift the numbers. Use the full EPC upgrade calculator for a customised version, the insulation savings calculator to choose between competing fabric measures, and BUS grant eligibility if a heat pump is on the shortlist.
Other current epc → c
| Archetype | Start → Target | Net cost | Annual saving |
|---|---|---|---|
| EPC F terrace → C | EPC F → C | £23100 | £420/yr |
| EPC E semi → C | EPC E → C | £12300 | £276/yr |
| EPC D semi → C | EPC D → C | £5350 | £171/yr |
| EPC D flat → C (this page) | EPC D → C | £7200 | £63/yr |