Wood fuel comes in many guises most commonly logs, pellets and wood chips. This article discusses logs. Heating your home with a wood burning stove is becoming increasingly popular. According to the forestry commission around 7% of UK homes currently use wood fuel in their homes to provide some or all of the heating. Not only is a stove cosy to sit around, wood is also a very low carbon fuel so you can do something to shift away from fossil fuel reliance.

In many cases trees are not felled primarily for firewood and it is the leftovers that are used for burning, for example the bark and sapwood that does not make for good building timber.

Wood fuel as it relates to C02 and global warming

Trees use the power of the sun to trap C02 from the air and convert it into more complex carbohydrates, combining the carbon from C02 with hydrogen from water (H20) and releasing the leftover oxygen in a process called photosynthesis. Trees use these carbohydrates to grow. Most of a tree is in fact trapped C02. When the tree is then burnt the C02 is released once again. In a sustainably managed forest each tree that is cut down is replaced so this results in no overall change in atmospheric C02 levels (not counting the C02 produced as a result of processing and transport).

Heating with wood is not carbon neutral (as many people do try to claim) because there is the processing and transport of the wood to consider, but compared to the C02/kWh of many other fuels wood does very very well indeed.

Global warming caused by human C02 emissions is already happening - if you doubt this then read through the Intergovernmental Panel on Climate Change (IPCC) report available from www.ipcc.ch. Switching your heating away from fossil fuels is one way in which you can help reduce C02 emissions and thereby slow global warming. You might be interested in our list of 20 tips on being environmentally friendly.

Insulate your house

In conjunction with changing your heating fuel you should also take steps to better insulate your home and thereby reduce your fuel needs. This includes improving your roof insulation, wall insulation, floor insulation as well as installing double glazed windows and draft proofing windows and doors. Not only will this reduce your C02 emissions but your fuel bills will also drop. Read this article about insulation.

Firewood

There is still a lot of sustainable firewood available in the UK with further unexploited capacity remaining. When sourcing your wood try to source from local suppliers as opposed to national suppliers that delivery by pallet. It is all very well burning wood to reduce C02 emissions but if the wood is being driven 500 miles to your door then it kind of defeats the point.

Seasoned firewood

It is very important that your firewood is well seasoned. Seasoned firewood is dry and ready for burning: it has been split to size and stored to dry for at least the summer season. This reduces the wood's moisture content down to reasonable levels for burning – typically 20% or lower. Very dry wood (such as wooden furniture in your house will have a moisture content of 10% or lower).

A sign that wood is seasoned is that the end grain of the logs may have small cracks in it (these cracks form as the wood shrinks due to water loss).

Another way to check is to split open a log and then use a moisture meter to measure the wood's moisture content. 20% or below is OK, above 20% not great, above 30% do not buy it (or be aware that it is unseasoned and will need storing before it can be burnt. You should not pay as much for it as for seasoned firewood).

Un-seasoned wood with a moisture content above 20% is not really suitable for burning and can be dangerous. A lot of the heat of the fire will be used to evaporate the water in the wood which means that your stove will run colder and you will not get as much heat for your money. The flue gases will also be colder as a result and you will get a LOT more tar condensation in your chimney which you want to avoid as this tar is the cause of chimney fires.

I will expand on chimneys and flues in another article.

Storing your firewood

I have a log shed where I keep my firewood. Ideally your shed should be fairly big – enough for a couple of tonnes of wood (don't worry that isn't as big as it sounds) so about 2 to 4 cubic meters.If you do not have the space then make it as big as possible – this will reduce the amount of firewood deliveries that you need every year. Your log shed should be sheltered from the rain but have sides that allow the wind to blow through as you want the wood to keep drying while you store it: the lower the moisture content the better it will burn. Recyclers amongst you might consider making the walls of your wood shed out of old pallets as these work very well and let air through at the same time. At the front of my shed I have some removable boards. I add these when the shed is very full to stop the firewood falling out of the front of the shed and then take them off as it empties as this makes it easier to reach in and get at the wood.

If space is limited the perhaps consider storing your wood against a wall with a small, simple roof above.

If you fell your own wood then the best thing to do is to split it immediately and then store it. If this is not possible then store it under cover and make sure you split it as soon as you can, storing it split for as long as possible. Some people store larger timbers in situ, putting down a couple of timbers on the ground to raise the pile off the earth and then covering the top with corrugated sheeting or similar to form a waterproof roof.

Splitting and chopping your wood

I use two types of axe to split my firewood. Outside I use a heavy maul which is a wide headed large axe to split oversize logs. A raised flat platform like a very large log is an ideal surface to chop wood on. The surface should be hard so that the energy from the axe transfers into the wood you are chopping and not into your chopping block. Inside I use a hatchet to make kindling to start the fire with. You might do this outside as it can cause mess and damage your floor.

Types of wood

Softwoods like pine burn fast and fairly hot and make good kindling to start your fire with. But pine will not last that long so once your fire is going you are better off switching to a hardwood. Hardwoods (like beech, ash, oak, chestnut) burn for longer and are ideal once the fire is going. Ash is great for burning and when freshly cut has a moisture content that can be as low as 30% which means that it takes less time to season than other, wetter woods. I personally like oak as it lasts for a long time because it is a very dense wood.Treated woods should not be burnt as noxious chemicals are released into the atmosphere. This is the problem with wood from building sites, skips and so on as you cannot be sure that it is untreated.

Finding a UK firewood supplier

There are a couple of searchable firewood supplier listings available online. The most up to date one, which is also free for firewood suppliers to join, can be found by following this link: UK Firewood supplier search.

You enter the first part of your postcode and then click 'search'. Firewood suppliers that deliver in your area are listed with the ones with fewest delivery areas displayed first (so the most local suppliers are listed first).This is a free service so if you are a firewood supplier and would like to be listed simply visit the page and fill in the simple application form.