Firewood logs
A traditional and ancestral means of heating, it is still the most widespread wood heating method in terms of volume. It is the one which is the least expensive but which also represents the most constraints for the user.
It is generally sold in stere (stack of 1m by 1m by 1m of logs) or in ropes (2 steres but this varies according to the Regions!). Their length depends on the supplier and your requests depending on your stove or boiler. Usually the choice is 1m, 50cm and 33cm. Small logs are generally sold (a little) more expensive because they require more work for the lumberjack but this is a miscalculation as there are more empty spaces on a cubic meter of small logs.
The best firewoods are hard hardwoods (hornbeam, oak, beech…) but conifers (fir, spruce, larch…) can also be used. But their combustion is faster and they generally keep less well outdoors.
For a good combustion, it is obviously necessary to use dry wood. This requires at least 2 years of drying after cutting, or even more for some species. Obviously, the wood must be unpolluted (paint, varnish, etc.).
Pollution from combustion of heating logs>
If the CO2 balance is almost zero, heating with logs is not entirely harmless for the environment. The combustion of wood mainly releases soot and CO as well as other chemical compounds in smaller quantities. In order to limit these releases, burning quality wood in a well-maintained, good-quality appliance is essential.
Indeed; burn wet wood causes fouling of appliances and flues (creosote and tars) and releases more polluting substances (soot, CO ...) while providing much less energy than dry wood. See pollution firewood.
Finally, the quantity of ash generated by the combustion of logs can be significant, especially when the proportion of bark is high.
Price and energy equivalent logs
The price of a cubic meter varied in 2009 between 25 € and 80 € depending on the size, the type of wood and whether it was dried or not. These prices vary greatly depending on the region and the quantity.
In terms of energy, 1 “ideal” cubic meter (30% vacuum in the stack, beech or oak essence, very dry) provides useful energy (ie taking into account the efficiency of your stove by around 70%. ) 1400 to 1500 kWh. This corresponds to approximately 160L of fuel oil with a modern boiler at 90% efficiency.
Given the variations and disparities in prices, it is difficult to make an objective comparison, but by taking a fuel oil price of 0.50 € / L, log wood is therefore approximately 50% cheaper than fuel oil ... on condition that you buy your wood properly. . Indeed; if the quality of fuel oil is extremely constant, wood is just the opposite! Oil also represents a comfort of use that heating with logs will never be able to achieve. To find out more, the reader will carefully read the introduction to this “wood heating” dossier: why choose firewood.