How Many Ster of Firewood Do You Need for 80 to 120 m²?

If you underestimate the amount, you can easily end up sitting in a cold living room in January.

Anyone planning to heat a flat or house of between 80 and 120 m² with wood quickly runs into a practical question: how many stacked cubic metres (Raummeter) or ster of firewood (Brennholz) do you need to genuinely make it through to spring? The honest answer depends on far more than floor area alone - insulation, the stove type, the wood species and even how warm you personally like it all play a part.

The factors that really determine firewood consumption

Before ordering a load of logs, it pays to look realistically at your own situation. Two properties with the same floor area can burn through completely different amounts of wood.

• Living area: 80 m² obviously requires less energy than 120 m², but the gap is not always linear - especially in older buildings.
• Thermal insulation: Well-insulated homes retain heat for longer. In poorly insulated properties, you are effectively “heating” the outdoors with a portion of your wood.
• Heating appliance: A modern wood burner, a stove, an inset fireplace or an open fire - efficiency varies massively.
• Region and climate: In snowy upland areas or the Alps, the stove will run for much longer than in milder lowland locations.
• Wood type and quality: Hardwood burns longer and provides more heat than soft conifers. Moisture content matters just as much.
• How you use it: Does the wood fire heat the whole house or mainly the living room? Is it kept going all day, or only in the evenings?

"For a well-insulated house of around 100 m² with a modern wood stove, an average of 4 to 6 ster per winter is enough for many households."

How many ster of wood is realistic for 80 to 120 m²

The figures below are not lab results; they are practical guide values that many households in Central Europe use for planning.

Typical consumption ranges by appliance type

• Modern wood burner / room-heating stove: For roughly 100 m² of living space, you will usually need 4–6 ster over the winter.
• Inset fireplace (closed insert): Here, it is sensible to allow 6–8 ster for 100 m².
• Open fire: Very inefficient - 12–15 ster for 100 m² is by no means unusual.

These ranges assume average insulation and normal winter temperatures. In draughty older houses or during prolonged cold snaps, consumption can rise noticeably.

Concrete examples for 80, 100 and 120 square metres

Living area & condition	Heating system	Expected requirement
80 m², poorly insulated	Open fire	10–12 ster, sometimes more
100 m², well insulated	Modern wood stove	4–6 ster
120 m², average insulation	Inset fireplace	7–9 ster
150 m², well insulated	High-output wood stove	8–10 ster

If you are torn between two values, you should plan for at least half a ster extra. Few things are more frustrating than having to order more when the first cold spell hits in March - often at higher prices.

Why insulation is often more important than the stove

Plenty of people spend their money first on an attractive stove with a glass front, but barely think about the building envelope. Yet this is exactly where the biggest savings can be found.

In a well-insulated home, heat remains in the rooms for hours even after the fire has gone out. In a poorly insulated older property, the fabric of the building cools down much faster. You notice it in two ways: you have to refuel more often, and you end the season with a much larger stack of logs gone.

"If you invest first in new windows, roof insulation or façade insulation, you can sometimes cut wood consumption by several ster per year."

Even modest steps make a difference: seal draughts around doors, shut shutters at night, put rugs on cold floors, and hang heavy curtains in front of poorly insulating windows. That reduces demand without committing to a major renovation.

Choosing the right wood: hardwood beats softwood

Not every log delivers the same amount of heat. What matters is the calorific value of the species and its moisture content.

Recommended wood species for winter use

• Oak: Very high heat output, burns slowly and produces long-lasting embers.
• Beech: A classic for living spaces; good flame pattern, plenty of heat, easy to regulate.
• Ash and hornbeam: Also high-quality hardwoods with strong heat performance.

Soft conifers such as spruce or pine burn down quickly and tend to give “fast heat”. That can be useful in the autumn shoulder season, but for long winter evenings you will use noticeably more volume.

Just as important is moisture content. Wood should be well below 20% residual moisture. Freshly cut timber typically needs two to three years to dry sufficiently.

"Damp wood wastes energy, creates smoke, soots up the stove and increases the risk of expensive chimney problems."

Storing, splitting, stacking: how to get firewood properly dry

Even excellent hardwood is of little use if it is stored incorrectly. Out of simple misunderstanding, many people make their biggest mistake here.

• Always store wood split, not in whole rounds.
• Stack it with plenty of air space and not too tightly, so air can circulate.
• Keep it off the ground - use pallets, battens or a proper log store base.
• Protect it from rain from above, but leave the sides open.
• Store it somewhere with sun and wind, not in damp cellars or sealed garages.

If you order wood now for use in two years’ time, you usually secure better pricing and achieve ideal drying - meaning more heat per log.

How households plan their firewood needs more realistically

Especially when you are new to heating with wood, it is common to misjudge how much you will actually need at first. A practical approach helps:

• In your first winter, order a little generously on purpose (for example, 1–2 ster more than the guide value).
• Across the whole heating season, keep a rough note of how much you really burn.
• At the end of the season, check what is left - that becomes your reserve for the next winter.

Once you have collected figures for two or three winters, you will know your typical requirement quite accurately. At that point, buying larger quantities can make sense, often with a volume discount.

Common mistakes that drive up wood consumption

Many complaints about “using too much” come down to a handful of familiar issues:

• Refuelling too late, so the fire keeps needing to be lit from scratch.
• Draughts caused by windows left on the latch in the room being heated.
• Thermostats on other radiators set too low, leading to constant switching back and forth between systems.
• Overfilling the firebox instead of maintaining a steady, even burn.
• Flue paths not cleaned and stove glass left dirty - efficiency drops.

A modern stove with clean glass, a chimney that is swept regularly and dry hardwood not only saves fuel, it also feels noticeably more comfortable.

A further note on safety and combining with other heating types

If you heat heavily with wood, you put far more strain on the chimney and stove than you do with an occasional “atmosphere fire”. An annual inspection by a chimney sweep and strict adherence to all required clearances from combustible materials are essential.

It can also be sensible to combine wood with another energy source, such as a heat pump, gas heating or a pellet boiler. Many people use a wood burner to cover peak demand on very cold days and reduce the load on central heating. That lowers overall consumption and creates a very pleasant indoor climate - particularly in older buildings, where low-temperature-only systems can sometimes struggle.

If you assess your home, your comfort expectations and your stove realistically, you can calculate your wood requirement fairly accurately. With dry hardwood, correct storage and an efficient appliance, it is possible to heat 80 to 120 m² so that winter can be long - but not cold.

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