How Many Steres of Firewood for 80 to 120 m²?

If you underestimate what you need, you could be left with a cold living room by January.

Anyone intending to heat a flat or house of between 80 and 120 square metres with wood faces a practical question: how many stacked cubic metres, or steres, of firewood are needed to last until spring? The answer is shaped by more than floor area alone; insulation, the stove, the wood species and even your own tolerance of cold all matter.

What really determines firewood consumption

Before ordering firewood, it is worth taking a realistic look at your own circumstances. Two homes of identical size can use very different quantities of wood.

• Living area: An 80 m² home naturally requires less energy than one measuring 120 m², although the difference is not always proportional, particularly in older properties.
• Thermal insulation: Well-insulated homes retain warmth for a long time. In poorly insulated buildings, part of the wood is quite literally used to heat the outdoors.
• Heating appliance: A modern wood-burning stove, log burner, inset fireplace or open fire can vary enormously in efficiency.
• Region and climate: In snowy upland areas or the Alps, the stove will run considerably longer than in milder lowland locations.
• Wood type and quality: Hardwood burns for longer and produces more heat than soft conifer wood. Its moisture content is just as important.
• How it is used: Does the wood fire heat the whole home or only the living room? Is it kept going constantly or used only in the evenings?

For a well-insulated home of around 100 m² with a modern wood-burning stove, 4 to 6 steres per winter is enough for many households on average.

How many steres of wood are realistic for 80 to 120 m²?

The figures below are not laboratory measurements, but practical guide values that many households in Central Europe can use for planning.

Typical consumption ranges by heating system

• Modern wood-burning stove / log burner: For around 100 m² of living space, winter use will usually be 4–6 steres.
• Inset fireplace (closed firebox): Allow for 6–8 steres for 100 m².
• Open fire: This is highly inefficient; using 12–15 steres for 100 m² is not unusual.

These estimates assume average insulation and normal winter temperatures. In draughty older homes or during prolonged cold spells, consumption rises noticeably.

Examples for 80, 100 and 120 square metres

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

If you are deciding between two figures, plan for at least half a stere extra. There is little more frustrating than having to order more during the first cold spell in March, often at higher prices.

Why insulation is often more important than the stove

Many people invest first in a stylish stove with a glass front, while giving little thought to the building fabric. Yet this is where substantial savings can be made.

A well-insulated home can hold its heat for many hours, even once the stove has gone out. In a poorly insulated older property, the structure cools down much faster. This shows up in two ways: you need to add logs more often, and the woodpile is significantly smaller at the end of the season.

Those who first invest in new windows or roof or façade insulation can sometimes cut wood consumption by several steres per year.

Even modest improvements can help: seal draughts around doors, close shutters at night, place rugs on cold floors and hang heavy curtains in front of poorly insulated windows. These steps reduce demand without immediately requiring major refurbishment work.

The right wood type: hardwood beats conifer wood

Not every log provides the same amount of heat. The key factors are the calorific value of the species and its moisture content.

Recommended wood species for winter heating

• Oak: Has a very high calorific value, burns slowly and produces long-lasting embers.
• Beech: A classic choice for living areas, offering attractive flames, plenty of heat and good control.
• Ash and hornbeam: Both are high-quality hardwoods with strong heat output.

Soft conifer woods such as spruce or pine burn away quickly and tend to provide “quick heat”. They can be useful during the milder autumn period, but for long winter evenings they require substantially more volume.

Moisture content is at least as important. Wood should have a residual moisture content well below 20 per cent. Freshly felled timber generally needs two to three years to dry sufficiently.

Damp wood wastes energy, creates smoke, blackens the stove and raises the risk of costly chimney problems.

Storing, splitting and stacking firewood so it dries properly

Even high-quality hardwood delivers little benefit when stored incorrectly. Through lack of knowledge, this is where many people make their biggest mistake.

• Always store wood split, rather than as whole logs.
• Build the stack so it is well ventilated and not packed too tightly, allowing air to circulate.
• Do not place it directly on the ground; use pallets, timber battens or a log store base.
• Cover the top to protect it from rain, while leaving the sides open.
• Store it where there is sun and wind, not in damp cellars or enclosed garages.

Anyone ordering wood now for use in two years’ time will usually secure better prices as well as ideal drying conditions - and therefore more heat from every log.

How households can plan their firewood needs more realistically

People new to heating with wood often misjudge their requirements at first. A practical approach can make planning easier:

• In the first winter, deliberately order a little more generously, for example 1–2 steres above the guide figure.
• Keep a rough record throughout the heating season of how much wood is actually burned.
• At the end of the season, check what remains; this becomes your reserve for the following winter.

After collecting figures over two or three winters, you will know your usual requirement fairly accurately. At that point, buying larger quantities can also be worthwhile, often with a volume discount.

Common mistakes that drive up firewood use

Many complaints about “excessive consumption” can be traced back to a few familiar problems:

• Adding logs too late, so the stove repeatedly has to be lit from cold.
• Draughts caused by windows being left on the tilt setting in the heated room.
• Setting thermostats on the other radiators too low, resulting in constant switching back and forth between heating systems.
• Overfilling the firebox instead of maintaining an even fire.
• Failing to clean flue passages and allowing the glass to become dirty, which reduces efficiency.

A modern stove with clean glass, a regularly swept chimney and dry hardwood not only saves fuel but also provides noticeably greater comfort.

A note on safety and combining wood with other heating systems

Frequent wood heating places far greater strain on the chimney and stove than an occasional fire simply for atmosphere. An annual inspection by a chimney sweep, along with compliance with all clearances from combustible materials, is essential.

Combining wood with another energy source can be sensible, such as a heat pump, gas heating or a pellet boiler. Many people use a wood-burning stove to cover peak demand on cold days and ease the load on the central heating system. This lowers overall energy consumption and creates a particularly pleasant indoor climate - especially in older homes, where low-temperature systems alone can sometimes reach their limits.

Anyone who assesses their home, personal comfort expectations and stove realistically can calculate their firewood requirement with reasonable accuracy. With dry hardwood, good storage and an efficient appliance, 80 to 120 square metres can be heated so that winter may be long, but it does not have to be cold.