Our advice

Winter airborne pollution is a serious problem in a number of New Zealand cities and provinces. Minimising pollution means keeping your woodburner working well. And that requires careful selection of the fuel you burn, and the way you burn it.

You can do your bit to reduce emissions, even if you have an older burner:

• Make sure the wood you burn is well seasoned. You'll need at least one year of well-ventilated drying, with the wood protected from wet weather - longer for harder woods. Wet wood cools the fire and reduces heat output, which greatly increases emissions.
• Don't burn big logs (over 110mm diameter).
• Don't burn treated wood, painted wood, or driftwood. They all cause dioxins and other toxic substances to be produced.
• Keep the fire hot - smouldering fires are very dirty. This means refuelling relatively often: perhaps every 20 to 30 minutes for radiata, less often for the harder woods.
• Don't load the firebox up and turn the heater down to burn overnight. This is the most polluting and least efficient way of running a woodburner. It doesn't burn as much because it cooks the firewood, produces little usable heat, gums the flue with soot, and pours out large quantities of pollution into the still night air.

Our view

There is a need in many parts of New Zealand for woodburners to produce as little pollution as possible. Because of the nature of the national environmental standard compliance test for woodburners, that is not happening right now.

It would take only small design/manufacturing adjustments for woodburners to produce fewer pollutants than they do now, when burning typical firewood, if the compliance test was updated.

Two things are needed:

• Manufacturers need to develop woodburners that can cleanly burn a wider range of woods.
• Regulators need to develop a test fuel and testing method that more closely matches typical firewood, and the way householders normally operate their burners.

"Low-emission" woodburners would then be worthy of their name. And then we could all breathe easier.