Like other areas throughout the world, Christchurch suffers from temperature inversions in winter which cause a smog-like atmosphere, resulting in poor air quality throughout the district.
Car exhausts, industry, commercial use and heating all contribute to this effect to a greater or lesser degree, but some industry experts say domestic wood heating has received more than its fair share of the blame.
Dave Pullen, President of the New Zealand Home Heating Association, says this is because all solid fuels, and appliances, are lumped together with open fires when addressing the issue of air quality.
“We readily accept the need to improve the situation in Christchurch and other areas. It has been one of the Association’s key mandates for many years now. As a trade body we have been instrumental in developing international emissions codes for wood burning appliances.”
Recent developments in wood heater design have resulted in emissions levels not thought achievable 10 years ago, and most appliances now produce a clean and environmentally acceptable burn, even when not operated correctly.
In addition to the familiar enclosed wood heater, specially designed high efficiency fireplace inserts burn almost as cleanly, yet provide the ambience and accessibility of an open fire.
The reality, it is claimed, is that in the air quality equation, wood heating is not the demon it seems.
Open fires in masonry chimneys appear to be the X factor – the unknown quantity.
While emission levels from wood burning appliances are measurable, little has been done to effectively assess pollution from the ordinary open fire.
“An estimated 45 000 open fires are still in regular use in the Christchurch area during the winter period,” said Mr Pullen.” And it is quite probable that more than 50% use coal as their main fuel.”
The real problem appears to be that no meaningful qualitative or quantitative research on the affect of open fires, and user habits, has yet been undertaken.
Because of design and low operating temperatures, there can be no control on the level of particulate matter emitted from the traditional open fire, even if only wood is burnt. But the situation becomes worse with coal.
“We know that open fires in masonry chimneys are extremely “dirty” by comparison to wood heaters, and we are not convinced that sufficient research has been done to ascertain their true impact on air quality” he continued.
Yet imposing controls on the open fire is difficult because so much relies on the integrity of the operator.
He says that properly conducted tests may well confirm the Association’s assertion that by simply replacing 25% of existing open fires with inbuilt wood burners, or high efficiency wood burning fireplace inserts, could reduce Christchurch’ s emissions levels by as much as 1.5 tonnes in just a 4 hour period on a cold night.
“While this figure has been derived from a number of different tests done by various laboratories, we believe a reduction of this magnitude could be realistic. Controlled research into this area is absolutely vital if Christchurch is to make significant advancements in reducing pollution attributed to solid fuel home heating” he said.
In calling for this research, Mr. Pullen said that there was good reason to believe that by introducing an incentive to convert fireplaces to wood heaters, combined with a public education programme, a substantial improvement in air quality would result.
“In Launceston, which suffers similar atmospheric conditions, a targeted education programme produced a substantial positive outcome in a very short space of time ” he said.
“If such a programme was introduced here, we would see similar results. Combine this with a heater or insert replacement programme, and we believe that the outcome would be quite startling.” he concluded.