What is the difference between an open fire and a closed fire?
Modern wood-burning fires and stoves have extremely high yields and excellent combustion. The devices are sophisticated and ensure that the wood is burned as cleanly and efficiently as possible. Unfortunately, this is something that we cannot say about the open fire. How is this possible?
The first major difference is in the fact that all modern wood-burning fires and stoves are closed by simply fitting them with a glass window/door. You may probably think that this is detrimental to heat production. But nothing could be less true! The fact that the fire is closed increases the temperature in the combustion chamber.
In addition, a great many devices have extra insulation in the form of a vermiculite back wall and the flue gases are expelled through an ingenious labyrinth. This results in clean combustion and also optimum enjoyment of the heat that is released.
As an indication: An open fire achieves just 15% yield precisely because it loses a great deal of warmth through the chimney. A modern wood-burning fire or stove achieves an average of between 60 and 80% yield. The emissions from an open fire in comparison with a good wood-burning fire are many times higher. When both are used to heat a room, the open fire emits 15 times more CO2 than the wood-burning stove and 50 times more fine particulates than the wood-burning stove.