When deciding where to buy firewood, we understand why many of you ask ‘can kiln-dried logs really be environmentally friendly?’ We get that it can seem counter intuitive to burn fuel to dry wood, which is then also burned as fuel, and appreciate that on the surface, it might seem like seasoning wood is better for the environment than kiln-drying it.
However, as always when it comes to sustainability, the answer is not that straightforward!
We need to look at a few different factors such as the type of kiln the logs are dried in, where they're sourced from and the impact on air quality.
But first, let’s look at the difference between seasoning and kiln-drying.
Why does wood need to be dried?
When wood is burned it emits particulate matter (PM), which are tiny particles of solids or liquids in the air. Some we can see, like smoke and soot, and others are microscopic, but they're all small enough that we breathe them in. This can cause health problems if inhaled in large amounts, so it’s important that we reduce them as much as possible.
Wet wood emits twice as much PM as properly dried wood, so making sure you only burn wood with less than 20% moisture is the best way to minimise your impact on air quality.
Drying wood is also important to make sure it can actually burn! When we (attempt to) burn wet wood, lots of energy is used to evaporate the water from the wood, which makes it much harder to light your fire, and results in a smoky mess with lower heat output.
What does it mean to season wood?
Seasoning means leaving wood to dry to below 20% moisture naturally. It needs to be stacked away from walls and floors, with good airflow and can take anywhere from six months to two years to get to below 20% moisture content.
What is kiln-dried wood?
Kiln-dried means the wood has been dried in a ‘kiln’ or chamber where heat, humidity and air flow are controlled to remove the moisture from the wet wood.
Depending on the kiln, it can take anywhere from a few days to a few weeks to dry the wood below 20% moisture.
How is the kiln powered?
In the UK, there are dozens of different types of kiln, powered by different types of fuel. The efficiency of a kiln and the fuel used to power it have a big impact on the sustainability of the process.
All of our Love Logs wood is dried in waste-wood or biomass fuelled kilns, and are super-efficient so very little energy is wasted.
Are kiln-dried or seasoned logs better for air quality?
As kiln-dried logs are more reliably dried to below 20% moisture than seasoned logs, it can be argued that kiln-dried logs are better for air quality.
Why are kiln-dried logs more reliable than seasoned logs?
Demand for firewood in the UK tends to be low throughout the summer, and much higher during the autumn and winter months, so log sellers make most of their money during the cold season, October – March.
However, the time taken to properly season wood depends on so many factors – the species and thickness of the wood, the weather over the time it’s seasoning and how well it’s been stacked to allow air flow can all impact the duration of time to get to 20% moisture.
Therefore, when seasoning logs, it’s very difficult to plan for them being properly dry at the start of the cold period, and to guarantee you’ll have enough to last the winter, especially if it’s an extra cold one.
The kiln-drying process is much more precise, and the time taken to properly dry wood is consistent when temperature, air flow and humidity can be controlled. Therefore, sellers of kiln-dried logs can accurately predict when their wood will be ready to burn.
It’s true that seasoned logs can be dried to an average 20% moisture and burn well, but in practice, it’s much more difficult to achieve than with kiln-drying so there can be a temptation to sell off seasoned logs before they’re properly dry, and the likelihood that you’re buying an inferior product is higher.
Therefore, if you want to guarantee that your logs will be below 20% moisture every time, and therefore emit less soot, smoke and PM2.5, kiln-dried logs are a much safer bet for air quality.
What else makes firewood environmentally friendly?
We can argue about the environmental impact of kiln-drying wood vs seasoning it all day, but in reality, the thing that will make the most difference to the sustainability of your wood is where it’s sourced from.
Firewood sold in the UK doesn’t have to be labelled as imported and over 50% of the wood sold in the UK has travelled thousands of miles to get to you, usually from Eastern Europe, where there aren’t strict procedures in place to make sure the wood is taken sustainably.
Buying British wood, taken from properly managed forests is the best way to minimise the carbon footprint of your fire.
Are kiln-dried logs environmentally friendly?
They can be! As long as they’re properly sourced in the UK from a sustainable forest and dried in a biomass fuelled, efficient kiln, packaged without plastic and not shipped halfway around the world, your kiln-dried logs are an environmentally friendly way to enjoy a cosy night by the fire.
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