Heat Pump Calculator

Total costs depend on the heat pump type: An air-source heat pump costs €15,000–25,000 including installation, a ground-source probe €20,000–35,000, and a water-source heat pump €25,000–40,000. Additional costs may include radiator replacement, hydraulic balancing, and buffer storage. Government heating subsidies (KfW, 30–80%) significantly reduce net costs.

For applications from 21 July 2026 (KfW program 458): the base subsidy is 30% of eligible costs (max. €28,000 for the first residential unit). On top come the Climate Speed Bonus (+16%, owner-occupiers only) when replacing oil, coal, gas floor or night storage heating, or gas/biomass heating at least 20 years old, and the tiered Income Bonus: +40% up to €30,000, +30% up to €40,000, +10% up to €50,000 taxable household income. A maximum combined rate of 80% is possible, i.e. up to €22,400. The efficiency bonus has been abolished.

The seasonal COP indicates how much heat a heat pump produces per kilowatt-hour of electricity used — measured over a full year. A COP of 3.5 means: 1 kWh of electricity produces 3.5 kWh of heat. The higher the COP, the lower the electricity costs. Good values: air-source 2.8–3.5, ground-source 3.5–4.5, water-source 4.0–5.0.

Yes, a heat pump can also be worthwhile in an old building — provided insulation is at least average and flow temperatures are below 55°C. Important steps: insulating the building envelope, possibly replacing small radiators with larger ones or underfloor heating, and hydraulic balancing. For poorly insulated old buildings (pre-1970), insulation should come first.

Electricity consumption equals heating demand divided by COP. A typical single-family home with 20,000 kWh heating demand and a COP of 3.5 uses about 5,700 kWh of electricity per year. At 30 ct/kWh, that's about €1,700 in electricity costs — significantly less than gas (€2,400) or oil (€2,200).

Yes, the bonuses are combinable! Base subsidy (30%) + Climate Speed Bonus (16%) + Income Bonus (up to 40%) = theoretically 86%, capped at 80% (owner-occupiers). For the climate bonus you replace an oil, coal, gas floor or night storage heating system, or gas/biomass heating at least 20 years old. The income bonus is tiered: 40% up to €30,000, 30% up to €40,000, 10% up to €50,000 taxable household income. From 1 Feb 2027 the climate bonus drops by 4 percentage points every six months.

Yes, hydraulic balancing is essential for efficient heat pump operation and has been mandatory for subsidized installations since 2024. It optimally adjusts each radiator so heat is distributed evenly and flow temperature stays as low as possible. Cost: €500–1,500, also eligible for subsidies.

Payback time depends on net costs, annual savings, and energy price increases. Typical values: With 30% subsidy replacing gas: 8–12 years. With 50–80% subsidy: 4–8 years. Rising gas prices (3%/year) further shorten the payback period.

With a PV system, heat pump electricity costs drop by 20–40%, depending on self-consumption share. At 30% self-consumption and a PV electricity cost of 8 ct/kWh, the effective electricity price drops from 30 to about 23.4 ct/kWh. Additionally, PV electricity reduces CO2 emissions to nearly zero for the self-consumed portion.

Air-source is cheapest (€15,000–25,000) and easiest to install, but has the lowest COP (2.8–3.5). Ground-source offers higher efficiency (COP 3.5–4.5) but needs space for ground probes or surface collectors. Water-source has the highest COP (4.0–5.0) but requires groundwater access and water rights permits.