What consumers should look out for when buying wood – Which firewood is more efficient

As natural gas prices along with electricity and oil prices have skyrocketed, many households both in Greece and in the rest of Europe have turned to firewood as an alternative heating solution this winter.

However, when consumers are asked to buy wood, they should pay special attention to certain points, as Dr. emphasizes to the Athens-Macedonian News Agency. Georgios Dalos, wood technologist professor of the University of Thessaly in the Department of Forestry, Wood Sciences and Design.

Types of firewood

– Beech

Beech, efficient in combustion, is ideal for a fireplace, as it gives a bigger flame, but without causing the smoke problems created by conifers. But be careful because it traps moisture in pockets, causing it to “pop” during combustion and throw lit pieces of coal

– Oak

Oak should be preferred for continuous use. It is not one of the woods that grabs easily, it is not convenient for kindling, but it burns slowly and efficiently and keeps the fire burning longer.

– Olive

Olive, like oak, should be preferred, as it has a longer burning time.

– Pine

In general, conifers, such as pine and fir, “grab” quickly, give a large flame and have a very high thermal capacity. We should use them mainly for kindling. Be careful when they are used as the main fuel because they can lead to unpleasant results that can even lead to a fire in the chimney or roof.

– Fir tree

Woods most used for kindling have a low density, burn quickly and give off a large flame.

According to Mr. Dalos, these four types of firewood are the main ones, however, there are also other types such as chestnut, poplar, holly, eucalyptus, lemon trees, etc.

Since firewood will be sold by the cubic meter again this year, according to Mr. Dalos, consumers should focus on the stacking method, making sure it is dense.

They should also ask for trafficking documents, since smuggling is no longer a criminal act only for the owner, but the person who procures them is also implicated.

Also, it is good to buy beech, oak and broad-leaved trees in general and to be careful not to buy coniferous trees and especially pine, since burning them can lead to a fire in the house.

For pelletconsumers should pay attention to the color of the woodto be light if it is from coniferous trees and a little dark from broad-leaved trees notes Mr. Dalos and adds that in both cases buyers should check the smell, which should refer to fresh wood.

How we stack and dry the wood

Special mention is made of the natural drying of the logs. Logs begin to lose water in winter, but in March the maximum water loss is observed (about 10%). In particularly hot summers fresh wood that is split in December and stored under cover can reach, as early as June, moisture levels of 20% and thus be suitable to be marketed as finished dry wood. However, in the case of wet summers the detectable differences are minimal and the value of 20% will be reached, but a month later.

Logs, as Mr. Dalos explains, that are stored covered dry relatively faster during the first months of winter. This advantage of covered wood is offset for uncovered wood during the summer months. The presence of a wooden shed, especially in very rainy areas, is considered appropriate, since it helps to limit the moisture that is recovered during the following autumn-winter period.

Provided the structural construction allows for adequate ventilation (slotted walls), storing wood under cover is strongly recommended. Compared to ripped wood, non-torn wood will reach 20% moisture levels two months later. Thus, in order to reach 20%, with a higher degree of safety and in order to maintain this moisture until autumn, it is suggested to split the low-quality round logs into firewood with a diameter of more than 10 cm before natural drying.

During wood processing and firewood stacking preparation, it is it is important to avoid, as far as possible, the accumulation of other materials on the logs-firewood. The treatment area must have a stable floor (cement or asphalt). The natural drying of the logs can be done either in open spaces or in covered and ventilated spaces, but in any case they must be protected from soil moisture and rain.

Finally, the data on the heating value of wood are of interest.

The maximum amount of heat produced by a 1kg mass of dry wood that burns completely (calorific value) varies between 3900-5100 kcal/kg. Broadleaf woods have a lower calorific value than coniferous woods, with average values ​​of 4350 kcal/kg and 4700 kcal/kg, respectively. Woods of higher density have a higher heating value. Coniferous species with resin give wood with a higher calorific value, because the resin has a high calorific value (about 8500 kcal/kg). The chemical composition of the wood is also of great importance. Lignin is characterized by a high calorific value, 6100 kcal/kg on average, while cellulose varies between 4150 – 4350 kcal/kg. Research has shown that the mesothermal value of broadleaves is greater in the wood than in the bark, while the reverse is the case with conifers, concludes Mr. Dalos speaking to APE-MPE.

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