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.
