After insulation work, a home becomes airtight — and without effective ventilation, moisture and pollutants build up. Heat-recovery ventilation (HRV/MVHR) solves this problem while recovering heat from the extracted air, and the Luxembourg government subsidises it by up to €4,000 through the Klimabonus 2026. Here is the complete guide.
New: estimate your grants in 30 seconds. Our renovation aid calculator works out your Klimabonus and bonuses according to the 2026 rates.
Why ventilation is essential after a renovation
Insulating and sealing a home without providing mechanical ventilation is a common mistake with serious consequences:
- Damp and mould: stale air can no longer escape, and condensation appears on cold walls and window frames.
- Air quality: VOCs, CO₂ and moisture accumulate, harming comfort and health.
- Heat loss from manual airing: opening the windows in winter wastes the heat your insulation has just saved.
Heat-recovery ventilation (MVHR) renews the air continuously and recovers up to 80–90% of the heat from the extracted air to pre-warm the incoming air — a virtuous circle alongside insulation.
Single-flow or heat-recovery ventilation?
| Criterion | Humidity-controlled extract-only | Heat-recovery (MVHR) |
|---|---|---|
| Principle | Extracts stale air, fresh air enters via windows | Extracts and supplies air, with a heat exchanger |
| Heat recovery | No | Yes (80–90%) |
| Comfort | Adequate | High (filtered air, no cold draughts) |
| Cost | More economical | Higher |
| Best for | Light renovation | High-performance renovation, well-insulated home |
For a well-insulated home, heat-recovery ventilation is the most coherent solution and the best subsidised.
How much does ventilation cost in Luxembourg?
| System | Indicative fitted price |
|---|---|
| Humidity-controlled extract-only ventilation | €2,000 – €4,000 |
| Decentralised (room-by-room) MVHR | €400 – €800 / unit |
| Centralised (whole-house) MVHR | €6,000 – €12,000 |
The price of a centralised MVHR system depends heavily on the ductwork network to be created — which is why it pays to install it during a renovation, before the interior finishes go in.
The Klimabonus 2026 grant for ventilation
The Klimabonus 2026 subsidises the installation of ventilation:
- Heat-recovery ventilation (MVHR): a grant of up to €4,000, subject to a minimum heat-recovery efficiency (generally ≥ 80%).
- Social top-up: lower-income households benefit from a 25% increase.
- Reduced 3% housing VAT applies to renovation work.
Important: heat-recovery ventilation must be installed after the insulation and air-sealing work, but before the interior finishes, so that the ducts can be routed. Plan for it from the design stage of your renovation. Check your exact amount with our aid calculator.
Getting your installation right
- Sizing: the airflow rate must match the floor area and number of rooms; under-sizing ruins the effectiveness.
- Ductwork airtightness: poorly fitted ducts create losses and noise.
- Maintenance: filters need changing 1 to 2 times a year; provide easy access to the unit.
- Coordination: ventilation fits into an overall project alongside external wall insulation and heating replacement.
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FAQ
What Klimabonus grant is available for heat-recovery ventilation in 2026?
The Klimabonus 2026 can cover up to €4,000 for a heat-recovery ventilation (MVHR) system that meets the minimum performance requirements (heat-recovery efficiency generally ≥ 80%), with a 25% increase for lower-income households.
Single-flow or heat-recovery ventilation: which should I choose?
Heat-recovery (MVHR) is recommended for a well-insulated home: it recovers 80 to 90% of the heat from the extracted air and filters the incoming air. Humidity-controlled extract-only ventilation, which is more economical, suits light renovations.
Do I need ventilation after insulation?
Yes. Effective insulation makes a home airtight; without mechanical ventilation, moisture and pollutants build up and cause mould and a deterioration in air quality.
When should ventilation be installed during a renovation?
Heat-recovery ventilation is installed after the insulation and air-sealing work, but before the interior finishes, so that the ductwork network can be routed.
How much does whole-house heat-recovery ventilation cost?
Expect to pay around €6,000 to €12,000 fitted for a centralised MVHR system, depending on the floor area and the ductwork network. After the Klimabonus grant, the remaining cost is significantly reduced.
