Facts about Sustainable Firewood

Consumers are increasingly turning to sustainable wood in the search for environmentally friendly renewable energy resource and to reduce their electrical and gas energy bills. Wood differs from other fossil fuels such as coal, gas and oil because it is part of the carbon/carbon neutral cycle. Although the fuels produce CO2, trees absorb CO2 and store it as carbon which makes up half the weight of the tree. When the wood is burned it releases only the same amount back into the atmosphere, the same as if the tree was left to rot!

Wood Seasoning

Freshly harvested wood contains a naturally high amount of water, between 65-90% depending on the species. Removing the water is known as seasoning. This term suggests a period of time, and for natural air drying up to two years is recommended.

When using unseasoned firewood, consider the cost per kilowatt of energy

• Wet or freshly cut wood average 1.0KW/h per kg
• Wood containing 60% moisture average 3.0 KW/h per kg
• Seasoned wood / kiln dried wood average 4.5 KW/h per kg





When buying firewood remember that first and foremost, it must be properly seasoned. The best way to get seasoned wood is to buy THIS years wood for NEXT year!
Unseasoned wood has the fresh clean look of new lumber at a Wood yard or DIY store and that same fresh look on the INSIDE when it's split. Though seasoned wood is darker on the outside, it's bone white on the inside.

You should be looking for gray, or darkened, brittle wood that has a lot of cracks in the inner rings. Wood that is seasoned looks grey, or dark due to the fact that it has been sitting in the sun, or has been stored indoors, drying, and collecting dust.

Storing Wood at Home

For perfect drying conditions the logs should be stored in a dry airy store, allowing the movement of plenty of air flow around the logs.

Stove Efficiency

Although open fires are very attractive they are extremely inefficient compared to wood burning stoves and even stoves will vary considerably.

The more efficiently a fire burns the less fuel is required.

Additionally the higher water content will prevent the gasses in the wood from igniting allowing them to escape - unused, up to 50% potential heat wasted!

The extra logs required (possibly more than three times as many) to produce the equivalent heat output, are a considerable waste of money, labour, transport and storage.

In addition to seasoned wood also consider the benefits of kiln dried wood

Energy Efficiency & Types of Wood

Hardwood broadleaf are slow growing deciduous trees with high density that burns slowly providing a steady heat output

Softwood conifers are usually fast growing with a low density that burns fast providing a rapid heat output

Both wood types have a similar calorific value per Kg but as the density of the softwood is approx half that of the hardwood, twice as much softwood is required to produce the same heat.

What Wood to Burn?

There are hundreds of different woods and wood types to choose from.
Each type of wood has different characteristics, some woods may burn for a long time and produce little heat, while others may have a shorter burn time but produce a good aroma, and some my give off lots of smoke and spit embers.

The following list will help to give you an idea of some of the different characteristics of a small sample of what is available:

• Alder - Gives a poor heat output and does not last very long.
• Apple - Has a steady slow burn when the wood is dry, good heat output with small visible flame with a pleasant odour.
• Ash - Excellent burning wood, gives great heat and flame output and also burns when green. Best heat output gained when the wood is dry.
• Beech - Good heat output but only fair when the wood is green. The wood is prone to shoot embers whilst burning.
• Birch - The heat is good but it the wood burns quickly, however a pleasant odour is produced.
• Cedar - Produces little flames but great heat and a wonderful odour. Provides a splendid noise when burned.
• Cherry - A slow burning wood that produces good heat and a pleasant odour.
• Chestnut - Produces small flames and nominal heat, This wood is also prone to shooting embers.
• Douglas Fir - Poor. Little flame or heat.
• Elder - Generates a lot of smoke and burns very quickly, coupled with not much heat.
• Elm - Commonly offered for sale. To burn well it needs to be kept for two years. Even when dry it is liable to smoke.
• Eucalyptus - Good dense hardwood, should be properly seasoned before use, but will produce good heat.
• Hazel - Good.
• Holly - Good, will burn when green, but best when kept a season to dry out fully.
• Hornbeam - Comparable in many aspects to Beech.
• Laburnum - Totally poisonous tree, acrid smoke, taints food and best avoided altogether.
• Larch - Crackly, scented, and fairly good for heat.
• Laurel - Has brilliant flame.
• Lime - Poor. Burns with dull flame.
• Maple - Good.
• Oak - Oak does not produce a very good flame and the smoke is acrid, but dry old oak is excellent for heat, burning slowly and steadily until whole log collapses into ash.
• Pear - Provides good heat combined with an extremely pleasant scent.
• Pine - Burns with a splendid flame, but is liable to spit.
• Plane - Burns pleasantly, but is naturally given to throw sparks if very dry.
• Plum - Good heat and aromatic.
• Poplar - Not recommended.
• Rhododendron - The thick old stems, being very tough, burn well.
• Robinia (Acacia) - Burns slowly, with good heat, but is unfortunately accompanied by an acrid smoke.
• Spruce - Burns at a extremely fast rate and with creates many sparks.
• Sycamore - Burns with a good flame, with moderate heat. Useless green.
• Thorn - Quite one of the best woods. Burns slowly, produces great heat with very little smoke.
• Walnut - Good, and so is the scent. A very aromatic wood.
• Willow - Poor. In a dry condition burns slowly, with little flame. Liable to spark.
• Yew - Slow burn with great heat and also has a pleasant scent.