Heat pump or carbon underfloor heating?

What the rule says

In Wallonia and Flanders, the rule limits direct electric heating, and names electric underfloor heating. Wallonia: 2,500 W at most per home up to 150 m², then 15 W per additional m², on any fitting, appliances already in place included. Flanders: 15 W at most per m² in a renovation subject to a permit or a notification with an architect; in an extension, the cap is calculated on the extension alone. Brussels: we have not found a cap. One room remains possible; a whole home, not within these limits.

In Luxembourg, direct electric heating cannot be the main heating of a building that is new, extended or converted. Partial heating remains possible: the regulation cites the bathroom.

In the Netherlands, a heating system that is fitted or renewed must reach a performance that direct electricity does not reach. The guide published by the public agency RVO rules out electric underfloor heating as main heating; the agency’s page allows local electric appliances controlled room by room. For a room heated as a supplement, the official documents point towards local heating being allowed, without naming electric underfloor heating: to be confirmed by the municipality.

The rule, country by country, with the texts

The short answer

In use, a heat pump consumes less electricity: that is its principle, and the measurements confirm it. To buy, it costs more, it has to be serviced, and it has to be replaced. The right choice therefore depends on your home, on the grants you are entitled to, and on the number of years you count over.

We sell carbon underfloor heating: read this page with that in mind. The first two measurements below come neither from us nor from the manufacturer.

What the institutes measured

The seasonal performance factor of a heat pump says how many kilowatt-hours of heat it gives for one kilowatt-hour of electricity, measured over a year in service.

Study	Buildings	Air-source heat pump	Ground-source heat pump
Fraunhofer IBP, 2017: 16 installations, two years	very energy-efficient new homes	2.6 at the unit; 2.2 including storage and distribution losses	3.2; 2.5
Fraunhofer ISE, 2020: 41 installations, one year	existing houses 15 to 170 years old	3.1 on average, from 2.5 to 3.8	4.1 on average, from 3.3 to 4.7

Direct electric heating, for its part, gives one kilowatt-hour of heat per kilowatt-hour of electricity. The gap therefore exists, and it is large: a factor of two to three for an air-source heat pump.

The first study notes that almost all the installations monitored could be improved: settings, flow temperatures higher than planned. The second, that the age of the house matters less than its level of insulation and the quality of the installation.

What the manufacturer calculated

The manufacturer of the carbon system does not dispute this gap. It argues that the gap is not enough to determine the total cost. Its example is a 2018 house in Litzelsdorf, Austria, 178 m², heated by its system. Heating consumption measured over the 2020-2021 season: 24.5 kWh per m² per year.

A 2022 university dissertation compared this house with what it would have cost with an air-to-water heat pump, over twenty years:

Item	Air-to-water heat pump	Carbon underfloor heating
Purchase	€25,000	€15,000, water heater included
Heating electricity	12.5 kWh/m² per year, for a factor of 4	24.5 kWh/m² per year, measured
Maintenance	€150 a year	none
Total over 20 years	€59,540	€34,080

With a factor of 2 for the heat pump, the dissertation arrives at about €66,000.

What this calculation does not include

The manufacturer says so itself, and it bears repeating:

No grant. Yet the heat pump receives grants in France, Flanders, Luxembourg and the Netherlands. Depending on your situation, a grant can wipe out the difference in purchase price.
German and Austrian prices, at €0.24 per kilowatt-hour.
A single house, recent and well insulated. In an old, poorly insulated home, consumption weighs more heavily, and the heat pump’s advantage in use grows.
No rise in the price of electricity, which would affect both.
A heat pump replaced after twenty years, with no repairs. The manufacturer considers this assumption favourable to the heat pump.
A single reading, the lowest. For the same house, the manufacturer’s table of readings gives 33.0 kWh per m² over one year: it is the “Litzelsdorf” row on the measured consumption page. The dissertation uses 24.5.

So it is not proof. It is an order of magnitude, on one case.

When the heat pump wins

A water circuit already exists: radiators or water-based underfloor heating in good condition. Only the heat generator is changed.
You are entitled to a large grant.
The home is large, poorly insulated, and will stay that way: consumption dominates the cost.
A lot of hot water is needed, produced at a single point.
The rule in your country rules out or caps direct electricity. In Wallonia, Luxembourg and the Netherlands, and in Flanders in a renovation subject to a permit, direct electric heating cannot be the main heating of a home, or only under an output cap: the rule, country by country.

When carbon underfloor heating wins

There is no water circuit, or it has to be redone: electric radiators, old convectors.
Height is limited: 5 mm, where water-based underfloor heating needs 45 to 65.
There is no room for an outdoor unit, a hot water cylinder, a plant room; or the neighbours are too close for the noise.
You are renovating room by room, or a single storey.
The home is well insulated: demand is low, and the purchase weighs more than consumption.
Rented homes, fully fitted-out apartment blocks: one meter and one thermostat per home, no maintenance and no heating charges to apportion. See the page in an apartment.

Doing the calculation for your home

The simulator compares the full annual cost, with the energy prices in your country: energy, maintenance, equipment. Choose “Air-to-water heat pump” as the heating to compare: it counts it with a factor of 2.9, the average ADEME measured in France on 90 air-to-water heat pumps fitted in houses, and shows the two costs side by side.

If you already have a heat pump quote, send it: we send you back the equivalent for the same area. Describe your project.

Updated on 9 October 2026.

Frequently asked questions

Your questions on this subject.

Does a heat pump really use four times less?

On a test bench, yes. In service, the Fraunhofer institutes measured an average of 2.2 to 3.1 kWh of heat per kWh of electricity for an air-source heat pump, depending on the study and on what is counted. Direct electric heating gives one.

So why fit direct electric heating?

Because consumption is only one line of the cost. Purchase, maintenance and replacement are others, and carbon underfloor heating can be fitted where a heat pump cannot find its place: no outdoor unit, no plant room, no water circuit.

Are there grants?

For a heat pump, yes, subject to conditions: MaPrimeRénov' in France, Mijn VerbouwPremie in Flanders, Klimabonus in Luxembourg, ISDE in the Netherlands. In Brussels, the grants are suspended; in Wallonia, loans have replaced them. None of these grants funds direct electric heating.

Can the two be combined?

Yes. Carbon underfloor heating can be fitted storey by storey or room by room: an added storey, a loft, an extension that the central heating can no longer serve.

How long does a heat pump last?

The manufacturer of the carbon system quotes the German heat pump association: up to 20 years at best, more often around 15. It states 50 years for its film, which has no moving parts.