THE BIRMINGHAM FIELD GUIDE / AIR SOURCE HEAT PUMPS
The newest room can have a different heat loss from the original house. On an altered Birmingham property, ask to see both construction phases in the survey.
START WITH THE PROPERTY
A Birmingham house extended in stages needs more than its total floor area recorded. Show where the original walls end, the age of each addition and any insulation work, so room losses reflect the actual construction.
BEFORE YOU ACCEPT A QUOTE
The coldest bedroom or newest open-plan space may drive a radiator change even if the system total looks reasonable. Compare each proposed emitter with its room load and ask which upgrades are included in the price.
LOCAL COST EVIDENCE / OCTOBER 2026
A quoted installation price depends on the work inside the home. Electricity use depends on the finished design and tariff.
We could not verify a representative local average for a fully installed, family-sized system. Published installer figures mix starting prices, example homes and different scopes. Averaging them would suggest more certainty than the evidence allows.
For a useful comparison, ask each installer to itemise the heat pump, cylinder, radiator changes, electrical work and commissioning, then show the price before and after any eligible grant.
about £890approximate annual cost if the October–December 2026 unit rate lasted a full year
This is a model, not a measured bill or an average for families with heat pumps. It starts with 12,711 kWh, the 2024 mean annual domestic gas use per meter in Birmingham. We apply 85% boiler efficiency and a heat pump seasonal performance factor of 3.1, then price the electricity at 25.60p per kWh in West Midlands.
Calculation: 2024 mean gas kWh per domestic meter × 0.85 ÷ 3.1 × Ofgem electricity unit rate. The result is rounded to the nearest £10. It assumes the gas meter's entire use was for heating and hot water, so cooking and other gas use can make it too high. It does not include existing electricity standing charges, servicing, or changes to your other electricity use.
Gas consumption is by local authority, except London, which uses the London region. Oxfordshire combines its five districts by gas-meter count. The electricity rate follows the distribution region for the place; Oxfordshire spans two regions. Actual cost depends on your heat-loss survey, hot-water use, chosen tariff, controls and the installed system's measured performance. Ask the installer for a property-specific annual estimate.
ILLUSTRATIVE QUOTE COMPARISON
One designer groups the original house and extension under a single floor-area estimate.
Another surveys their different wall and floor construction and lists radiator changes by room.
Compare room losses at the same design condition. Ask why any radiator retained by one designer still meets its room's load at the proposed flow temperature.
ANOTHER PROJECT AT THE SAME ADDRESS?
NEXT STEP IN BIRMINGHAM
A good room calculation still needs room for a cylinder and a serviceable outside unit. Show potential locations so those enabling works can be included in the quote.