Underfloor heating with a heat pump: what does it cost in Luxembourg, and does it work in a renovation?
By Yacine Sahnoune, founder of renov.lu
In Luxembourg, wet underfloor heating costs €80 to €160 per m² installed, excluding the heat pump: €80 to €120/m² in a new build, €120 to €160/m² in a renovation with a low-profile system. Heated with water at 30-40 °C, it lets an air-to-water heat pump reach a SCOP of 4.4 to 4.7, against 2.5 to 3 on high-temperature radiators.
- Installed price, excluding heat pump: €80 to €120/m² in a new build (screed), €120 to €160/m² in a renovation (low-profile or dry system)
- Fully equipped 150 m² house: €12,000 to €22,000 for the floor, plus the heat pump (air-to-water €12,000 to €24,000)
- Efficiency: water at 30-40 °C, SCOP 4.4 to 4.7 with air-to-water, against 3.3 to 3.8 on low-temperature radiators
- Thickness: 3 to 7 cm for a low-profile system, 12 to 18 cm for a conventional wet screed
- Floor covering: total thermal resistance of no more than 0.15 m²·K/W, adhesive and underlay included
- Lifespan: 50 years or more for the pipes, against 15 to 20 years for an air-to-water heat pump
Underfloor heating and heat pump: estimate your project
The simulator estimates the price and grants for the heat pump; installers established in Luxembourg then price the whole system, floor included.
Price of wet underfloor heating in Luxembourg
Wet underfloor heating costs €80 to €160 per m² installed in Luxembourg, heat pump not included. New builds are the cheapest because the pipes are laid before the screed; in a renovation, low-profile systems cost more per m² and bring ancillary work.
| Situation | Installed price, excl. heat pump | What drives the price |
|---|---|---|
| New build, wet screed or flowing screed | €80 – 120/m² | Insulation, pipes, manifold, screed; height planned from the design stage |
| Renovation, low-profile or dry system | €120 – 160/m² | Grooved panels, possible removal of the old floor, levelling |
| Fully equipped 150 m² house | €12,000 – 22,000 | Excluding heat pump; in a renovation, ancillary work accounts for 20 to 30% of the budget |
In a renovation, the raised floor level often means trimming or replacing doors, adapting thresholds and moving sockets: these items must be on the quote. The heat pump comes on top: €12,000 to €24,000 including VAT for air-to-water, see the cost of a heat pump in Luxembourg.
Why underfloor heating and heat pumps go together
Underfloor heating heats a house with water at 30-40 °C, against 55 to 80 °C for radiators. A heat pump uses less electricity the cooler the water it produces: on underfloor heating, an air-to-water heat pump reaches a SCOP of 4.4 to 4.7, which means up to 30% less electricity than on low-temperature radiators and almost half as much as on high-temperature ones.
The large exchange surface of the floor also gives gentle, even warmth with no visible radiators. Efficiency figures by type of emitter are in our guide to heat pumps in Luxembourg.
New build or renovation: when can you fit underfloor heating?
In a new build, underfloor heating fits in without constraints. In a renovation it is possible if four conditions are met: available height, strength of the existing floor, insulation under the floor and sufficient insulation of the house.
- Height: at least 3 to 5 cm for a low-profile system, 12 to 15 cm for a conventional one. Below a 2.40 m ceiling height, choose a low-profile system.
- Load: a wet screed weighs about 120 kg/m², often too much for an old timber floor; a dry system weighs 15 to 25 kg/m².
- Insulation below: a thermal resistance of at least 0.75 m²·K/W above a heated basement, 2 m²·K/W on a ground-bearing slab or crawl space, otherwise the heat goes downwards.
- Insulation of the house: a heated floor delivers 40 to 70 W/m², i.e. 6 to 10.5 kW for 150 m². If heat losses in a cold spell exceed this, insulate first or add radiators.
In a renovation, the best compromise is often underfloor heating on the ground floor, where the floor is being redone, and low-temperature radiators upstairs. The heat pump is then set to the temperature the radiators need, usually 45 to 50 °C in a cold spell, with a mixing valve for the floor. The room-by-room calculation is the same as for sizing the heat pump.
The three types of wet underfloor heating
The choice of system depends mainly on the available height and on how long you can wait before laying the floor covering.
| Type | Total thickness | Wait before covering | Use |
|---|---|---|---|
| Conventional wet screed (insulation + pipes + cement screed) | 12 – 18 cm | 4 to 8 weeks of drying | New build |
| Anhydrite flowing screed | 8 – 12 cm | 4 to 12 weeks depending on humidity | New build, large flat areas |
| Low-profile or dry system (grooved panels) | 3 – 7 cm | A few days | Renovation |
With a wet screed, a gradual heat-up is needed before normal use and before laying the covering: the works schedule must allow for it.
Which heat pump for underfloor heating?
All air-to-water and ground-source heat pumps work with underfloor heating; the best suited modulate their output (inverter technology), because a high-inertia floor needs steady heat rather than on-off cycles.
- Air-to-water: the usual choice; it runs far from its temperature limit, in its best conditions.
- Ground source: the most efficient combination, with a SCOP of about 5 thanks to the stable ground temperature.
- Existing floor: a floor in good condition connects easily to a new heat pump. If it is more than 20 years old, have it flushed and balanced before commissioning.
Which floor coverings work with underfloor heating?
The rule is simple: the total thermal resistance of the covering, adhesive and underlay included, must not exceed 0.15 m²·K/W. Above that, the heat pump has to produce hotter water and loses efficiency.
- Tiles, stone, polished concrete: ideal, they pass the heat through almost without loss.
- Engineered wood and laminate: compatible if labelled for underfloor heating, with a suitable underlay and boards of limited thickness.
- Solid wood: not recommended, as it insulates and moves with temperature changes.
- Carpet and thick coverings: avoid, they block the heat.
Settings: weather compensation, night setback and cooling
Underfloor heating is controlled by the heat pump’s weather compensation curve, which adapts the water temperature to the weather: about 28 to 30 °C in mild weather, 40 to 45 °C in a cold spell. Set too high, it makes the heat pump use more for the same comfort.
The floor reacts over several hours: a night setback of more than 2 °C forces a long reheat in the morning that cancels the saving. Room thermostats linked to the manifold adjust the temperature of each zone.
Cooling: with a reversible heat pump, the floor can circulate cool water in summer and lower the indoor temperature by 2 to 3 °C. To avoid condensation, the water does not go below 15-16 °C and a humidity sensor cuts the cooling when the air is too humid. It is not air conditioning, but summer comfort with no extra unit.
Grants and VAT for underfloor heating with a heat pump
Underfloor heating has no grant of its own: it is the heat pump that receives the Klimabonus, €12,000 for air-to-water and €14,000 for ground source when ordered by 30 June 2027 to replace fossil or electric heating.
When a heat pump replaces an existing boiler, adapting the heat distribution system is supported at 50% of the costs, up to €2,000 for a house: ask Klima-Agence (8002 11 90) to confirm that your floor falls under this item, and have it on a separate invoice line. Heating work in a main residence at least 10 years old is invoiced at 3% VAT. Amounts and conditions: heat pump grants.
Maintenance and lifespan of underfloor heating
Wet underfloor heating needs little maintenance and outlasts the rest of the installation: 50 years or more for the pipes, against 15 to 20 years for an air-to-water heat pump, which can be replaced without touching the floor.
- Every year: bleed the loops from the manifold and check the pressure, usually between 1.5 and 2.5 bar.
- Every 5 to 7 years: flush the system if cold zones appear, and check the corrosion inhibitor.
- Prevention: pipes with an oxygen barrier and a sludge separator on the return.
Get your underfloor heating and heat pump priced
The floor and the heat pump are sized together: ask for a single quote covering both, with a room-by-room heat calculation. The simulator gives a first estimate of the heat pump and its grants in 2 minutes.
One quote for floor + heat pump
Get 3 quotes from installers established in Luxembourg, free and without obligation.
Frequently asked questions about underfloor heating with a heat pump
How much does wet underfloor heating cost in Luxembourg?
Budget €80 to €120 per m² installed in a new build and €120 to €160 per m² in a renovation with a low-profile system, heat pump not included. For a fully equipped 150 m² house, the floor alone costs €12,000 to €22,000. In a renovation, allow 20 to 30% for ancillary work: doors, thresholds, sockets.
Can underfloor heating be fitted in an existing house without tearing everything up?
Yes, with a 3 to 7 cm low-profile or dry system laid on the existing floor, with no wet screed and usable within a few days. The substrate must be flat and sound, there must be enough ceiling height left and the floor must be insulated underneath. Many renovations limit it to the ground floor and keep low-temperature radiators upstairs.
Does the Klimabonus pay for underfloor heating?
Not directly: the Klimabonus supports the heat pump, €12,000 for air-to-water ordered by 30 June 2027 to replace a boiler. When a heat pump replaces an existing boiler, a bonus covers 50% of the cost of adapting the heat distribution system, up to €2,000: ask Klima-Agence to confirm that your floor qualifies. 3% VAT applies in a main residence at least 10 years old.
Which floor covering should I choose for underfloor heating?
Tiles, stone and polished concrete are the best choices. Engineered wood or laminate works if it is labelled for underfloor heating and if covering, adhesive and underlay together do not exceed a thermal resistance of 0.15 m²·K/W. Avoid solid wood and thick carpet, which insulate the floor and force the heat pump to work harder.
Is underfloor heating enough to heat a poorly insulated house?
Not always. Underfloor heating delivers 40 to 70 W per m², i.e. 6 to 10.5 kW for 150 m². If the house’s heat losses in a cold spell exceed this output, which is common in an unrenovated pre-1990 house, insulate first or add low-temperature radiators in the most exposed rooms. A heat-loss calculation settles the question before the works.
Can underfloor heating cool the house in summer?
Yes, if the heat pump is reversible. The floor then circulates cool water, never below 15-16 °C to avoid condensation, and lowers the indoor temperature by 2 to 3 °C. A humidity sensor cuts the cooling when the air is too humid. The effect is gentler than air conditioning, but with no extra unit and no blown air.