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Amperecalc

Heating

Heat pump or gas boiler — which costs less?

Whether a heat pump pays off comes down to a single ratio: electricity price divided by seasonal performance factor, against gas price divided by boiler efficiency. Everything else is detail — which this calculator also models.

How we calculate

Calculation model

  1. 01

    Floor area and building standard give the specific space heating demand; hot water is added from the number of occupants.

  2. 02

    Heat pump electricity follows from heat demand divided by the seasonal performance factor, derived from source and flow temperature.

  3. 03

    The comparison case is priced using boiler efficiency, fuel price and the statutory carbon price.

  4. 04

    Investment less subsidy, together with the annual cost difference, gives the payback.

Good to know

  • The German BEG subsidy for a heating replacement is 30 percent base, plus speed and income bonuses up to a maximum of 70 percent, capped at €30,000 of eligible cost.
  • Flow temperature drives the seasonal performance factor: every degree lower is worth roughly 2.5 percent efficiency.
  • The carbon price on fossil fuels keeps rising, shifting the comparison further towards the heat pump each year.

Law & subsidies

What applies in Switzerland

Regulation determines the limits and tariffs this calculator works with.

A carbon levy on fuels — with redistribution

Fossil fuels carry a steering levy. A large part flows back to the population through health insurance and pension contributions.

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The levy is considerably higher than the German carbon price and makes heating oil and gas correspondingly more expensive. Households that burn little fossil fuel get back more than they pay in — that redistribution is the actual incentive.

For the heat pump calculation this means the cost advantage over gas or oil is structurally larger in Switzerland than in Germany, even though electricity costs about the same.

Heating replacement is regulated by the cantons

Rules and subsidies for replacing a heating system are set by the cantons, not the federal government.

Of every topic on this page, this is the most regionally fragmented. Checking your canton's rules is essential.

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The cantons' model energy regulations are a template that each canton adopts or amends independently. In several cantons a fossil system may only be replaced if a renewable solution is demonstrably uneconomic.

Subsidy amounts also differ substantially by canton, and sometimes again by municipality. A single national figure would mislead — the calculator uses an average that you should override.

This compilation is orientation, not legal advice. Rules in this field change several times a year — check the linked primary source before you invest, or ask a certified specialist.
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Frequent questions

Answered briefly.

Does a heat pump require underfloor heating?

No. What matters is the required flow temperature, not the type of emitter. Many existing buildings manage 50 to 55 °C after replacing a few radiators — enough for a seasonal performance factor around 3.0 to 3.4.

What is a good seasonal performance factor?

For air-source heat pumps in existing buildings, 3.0 to 3.5 is realistic; in new builds with underfloor heating, 4.0 to 4.5. Ground-source units sit roughly 0.5 to 1.0 higher.

Is combining it with photovoltaics worth it?

Yes, but less than often assumed: heat demand falls in winter, solar yield in summer. A rooftop array typically covers 20 to 30 percent of heat pump electricity — considerably more for summer hot water.

Rooftop PV calculator

Yield, self-sufficiency and return of a rooftop array over 25 years.

Payback calculator

Net present value, internal rate of return and break-even for any energy investment.

Carbon footprint

Electricity, heat, mobility and diet — and what each measure actually achieves.

All results are model calculations based on your inputs and statistical reference data. They do not replace individual professional planning.

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