How many kW does my wood-burning stove need? New build or old building makes the difference
It is not the room size that matters but the insulation. Why we almost always recommend a heat-storage stove in new builds – and when more output is fine.
The most common question in our showroom is: how much output do I need? Our first question in return is always: Is it a new build or an existing house – and has it been renovated? Because how much heat a room needs depends far more on the insulation than on the square metres.
Rules of thumb for heat demand
- New build (current energy standard): around 30–50 watts per square metre
- Renovated older building: around 60–90 watts per square metre
- Unrenovated older building: around 100–150 watts per square metre
An open-plan living and dining area of 50 m² therefore often needs only around 2 kW in a new build – but 5 to 7 kW in an unrenovated older building.
Why a heat-storage stove in a new build?
Even small wood-burning stoves deliver 4 to 5 kW. In a well-insulated new build, that is more than the room can absorb: it quickly gets too warm, you reduce the air supply, the wood burns poorly and the glass soots up.
For new builds we therefore almost always recommend a stove with a lot of storage mass – such as a wood-burning stove with storage stones, a heat-storage stove or a masonry heater (Grundofen). The storage mass absorbs the heat during burning and releases it gently and evenly over many hours. This keeps things comfortable without the room overheating.
Ventilation system? Then room-air-independent
New builds are very airtight and often have controlled residential ventilation. As a rule, this requires a room-air-independent (sealed) stove approved for operation with ventilation systems – it draws its combustion air from outside via its own duct – or a suitable safety device. We coordinate what applies in your case with your district chimney sweep.
In older buildings it can be more
In older houses with a higher heat demand, a wood-burning stove with 6 to 8 kW or a water-bearing appliance can noticeably relieve the heating. Here, what matters above all is the chimney (cross-section, height, condition) and whether only one room or several rooms are to be heated.
Our advice
Room size alone is not enough to make the right choice. Bring a floor plan, photos of the installation location and your chimney data to the consultation – then we will work out the right output together. Our Stove Finder gives you an initial orientation.
