Compare heat pump, gas, oil and pellets including investment, price rise and total cost.
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Living area times heat demand per square meter equals annual heat need in kWh. The calculator derives required fuel (or electricity) per system, accounting for efficiency (gas/oil) or seasonal performance factor (heat pump). Over the horizon it sums investment, annual energy cost and a chosen price escalation.
For modern, well-insulated homes (40–80 kWh/m²) with a SCOP from 3.5, a heat pump usually wins: electricity costs more per kWh, but you need far fewer kWh per kWh of heat than with gas. In old buildings with high heat demand and old radiators, gas or pellets may still be cheaper. CO2 pricing increases yearly, pushing fossil fuels up over time.
Choosing a heating system is a 15 to 25 year investment. For a typical single-family home with 130 m² living area and a specific heat demand of 120 kWh/m²·year (a renovated 1990s building), the annual heat load is roughly 15,600 kWh. A gas condensing boiler at 95% efficiency needs 16,400 kWh of gas — at 12 cents per kWh that is 1,970 EUR in year one. A modern heat pump with a seasonal coefficient of 3.5 needs just 4,460 kWh of electricity — at a special heat-pump tariff of 0.30 EUR per kWh that is 1,340 EUR per year.
At first glance, gas looks competitive year one, but the gap widens over decades. With 3% annual price growth, year 20 gas costs 3,450 EUR while the heat pump costs 2,350 EUR. Cumulated over 20 years, the gas heater pays about 52,900 EUR in fuel plus 12,000 EUR investment — around 64,900 EUR. The heat pump sums to about 35,900 EUR in electricity plus 28,000 EUR investment (after the German BAFA subsidy) — around 63,900 EUR. In this scenario the heat pump matches and from year 21 onward becomes clearly cheaper. With higher energy prices or a better SCOP the gap widens further.
Three factors are often underestimated in lay discussions: first, the CO2 price (45 EUR/t in Germany in 2024, rising to 55 EUR/t in 2025 and beyond) which adds roughly 1 to 1.5 cents per kWh per year to gas and oil. Second, the seasonal heat-pump coefficient — in a poorly insulated old building with radiators instead of underfloor heating it can drop to 2.5, ruining economics. Third, Germany's 2024 building energy act (GEG, the so-called "heating law"): newly installed oil and gas systems must run on 65% renewable energy by 2045 at the latest — pure fossil units lose grandfathering protection over time.
From living area, specific heat demand, efficiency or seasonal coefficient, and energy price, the annual cost emerges — the calculator cumulates it with price escalation over the horizon:
Heizwärmebedarf_Jahr = Wohnfläche_m² * spezifischer_Bedarf_kWh/m²
Brennstoffbedarf = Heizwärmebedarf / Wirkungsgrad (Gas/Öl/Pellet)
Stromverbrauch_WP = Heizwärmebedarf / JAZ (Wärmepumpe)
Kosten_Jahr_y = Brennstoff/Strom * Preis * (1 + Preissteigerung)^(y-1)
Gesamtkosten = Investition + Summe aller Kosten_Jahr_yAll examples for a single-family home of 130 m² over a 20-year horizon at 3% price growth.
The comparison abstracts from many details that may be decisive in individual cases: maintenance costs (typically 200 to 400 EUR per year for gas/oil, 100 to 200 EUR for heat pumps) are not included. Chimney-sweep fees do not apply or are reduced for heat pumps and pellets. Heat-cost billing, additional buffer-tank costs, hydraulic balancing, or borehole costs for ground-source heat pumps — all missing. The CO2 price is only indirectly modelled via the general escalation factor; in reality it rises faster than other energy costs. For an informed decision a certified energy consultant (BAFA-registered, with 50–80% government subsidy on consulting fees) is worth the cost. On a 20,000 to 30,000 EUR investment, a 500 EUR consultant fee is money well spent. This page is informational, not energy advice.