heating-cost-calculator

Your annual gas bill shows total consumption in kWh (or m³ — multiply m³ by the calorific value printed on the bill, typically 10–11 kWh/m³). For heating oil, multiply litres consumed by 10 kWh/litre. Divide the annual kWh by your living area in m² to get your specific energy consumption in kWh/m²/year — this is the key benchmark. Compare it to the table above to see which building standard your home currently matches. If your consumption is 190 kWh/m²/year in an apartment you thought was "normally insulated," it is behaving like an unrenovated pre-1978 building.

Heat pumps work most efficiently when the heating system can operate at low flow temperatures (35–45°C for underfloor heating or oversized radiators). In old buildings with standard radiators designed for 70–80°C flow temperature, a heat pump must work much harder (lower COP, higher electricity cost), which can make it less economical than gas. Before investing in a heat pump for an old building, the typical recommended sequence is: (1) insulate the building envelope (roof, walls, windows) to reduce heating demand; (2) replace radiators with oversized versions or add underfloor heating in at least the main rooms; (3) then install the heat pump. Without steps 1 and 2, the heat pump investment often does not pay off economically in an old building.

The main subsidy programme is the BEG (Bundesförderung für effiziente Gebäude) administered by BAFA and KfW. For heat pump installation: up to 30% basic subsidy + 5% "Klimageschwindigkeitsbonus" (if replacing a gas/oil boiler before 2028) + 5% income bonus for households with income ≤€40,000/year — maximum combined: 70% of eligible costs, capped at €30,000 per unit. For insulation measures (wall, roof, windows): 15–20% subsidy through BEG Einzelmaßnahmen. Important: the BEG subsidy must be applied for BEFORE starting construction (nicht rückwirkend). Changes to BEG rates and conditions have occurred frequently — check bafa.de for the current conditions before planning.

The calculator estimates are typically within ±15–20% of actual bills for standard cases. The main sources of deviation are: personal heating behaviour (room temperatures, ventilation habits), actual local climate (the calculator uses long-term averages), and specific building characteristics that differ from standard benchmarks. For a more precise estimate, enter your actual consumption from last year's bill and your exact energy price — the calculator will use these directly instead of estimates. The result will then reflect your actual consumption pattern rather than a building-standard benchmark.