When logs are freshly cut, depending on the species, they will have a moisture content of around 50 – 80%. With these levels of moisture content each kilogram of wood can contain between 500 and 800 grams of water. Therefore, a log weighing 1500 grams with a moisture content of 50% contains half a litre of water, which means most of the energy in the freshly cut log is used to evaporate the moisture and very little heat is produced which is the primary purpose of burning logs.

You should also consider the amount of air required to burn wood with high moisture content, as each cubic metre of air flowing up the chimney is an extra cubic metre of fresh cold air heating the.

Other advantages of using kiln dried logs is that the kilning temperature of 70 degrees centigrade sterilizes the logs and removes all traces of wood boring insects etc, and when dry, and burnt efficiently wood is a renewable carbon neutral source of energy.