Portsmouth and the Isle of Wight are predominantly gas-connected. The Solent coast's mild maritime climate gives heat pumps good efficiency — one of the better SCOP environments in England. Portsmouth's dense urban terraces can be trickier for ground-source installation, but air-source and air-to-air (£2,500 BUS grant) suit most property types. The South East has strong MCS installer coverage.
Heat demand starts from typical UK figures by property type (detached ~14,000 kWh/yr, semi ~12,000, terrace ~10,000, flat ~6,000) and is adjusted for bedrooms and EPC rating. An EPC C home uses ~15% less heat than D; an F home uses ~30% more.
Heat pump electricity = heat demand ÷ SCOP. We assume SCOP 3.0 for ASHP, 4.0 for GSHP and 2.5 for air-to-air systems. Real-world SCOP depends on radiator sizing, hot water demand and your installer's setup quality.
Current cost uses 6.5p/kWh gas, 9p oil, 12p LPG. Override with your actual bill for a more accurate result.
Install costs: ASHP £10–14k typical, GSHP £18–25k (deeper bore + groundwork), air-to-air £4–7k. The Boiler Upgrade Scheme grant is deducted. We compare against the cost of replacing a like-for-like boiler (~£3,000) to give an honest "incremental" payback.
Estimates only. SCOP is highly installer-dependent and your savings hinge on getting the radiator sizing right. Get at least 3 quotes from MCS-certified installers.