Department of the Environment and Heritage, May 2004
Woodsmoke pollution from woodheaters is a major environmental problem in regions throughout Australia. Woodsmoke contains a range of air toxics pollutants, including benzene, formaldehyde and polyaromatic hydrocarbons. However, the principal pollutant associated with woodsmoke is particles.
The Australian/New Zealand Standard, AS/NZS 4013 is used to regulate the maximum particle emission rates in most States and Territories within Australia. The particle emissions performance of retail models, however, may not be the same as certification results because (a) woodheater models sold may differ from models tested in the laboratory and (b) woodheaters may have been modified, for example, to achieve longer burn times.
In recognising the need to better characterise woodheater emissions from models actually sold to the public, a National Woodheater Audit Program, with funding from Commonwealth, NSW, Victorian, Western Australian and Tasmanian environment agencies, was implemented. Retail models representing popular Australian models were purchased from retailers and tested for emissions performance under AS/NZS 4013 conditions. These results were then compared with their certified emissions values. As a concurrent exercise, the design features of key woodheater components were compared against design specifications to determine if this relatively inexpensive test is a reliable proxy for costly laboratory emissions testing.
To address these issues, the AHHA Testing Laboratory was contracted to carry out woodheater testing, both within the laboratory (AS 4013 emissions tests), and on-site design specification tests to determine if they are a reliable proxy for costly emissions testing. The 12 most popular nationally available models were tested for emissions and design specifications, with a further 35 models tested for design specifications alone.
Results from the Program showed that the extent of non-compliance was significant:
- 58% (7 out of 12) of woodheaters failed to meet AS/NZ 4013 particle emission limits
- 55% (26 out of 47) of woodheaters had one or more serious design faults that could affect performance
- 72% (34 out of 47) of woodheaters had one or more labelling faults that could affect emissions performance
An analysis of heaters tested for emissions performance showed that the presence of engineering design faults was a good indicator of emissions compliance:
- 100% (7 out of 7) of woodheaters that failed to comply with AS/NZ 4013 emission limits had one or more serious design faults
- 20% (1 out of 5) of woodheaters that complied with AS/NZ 4013 emission limits had one or more serious design faults
The most common engineering design fault associated with emissions and engineering design non-compliance was primary air inlets that were smaller than originally specified in design drawings.
These results indicate that the degree of non-compliance, in terms of emissions performance, engineering design specifications and labelling requirements, is significant and needs to be addressed by manufacturers and/or retailers. Further auditing is required to monitor the compliance of woodheaters available for retail sale. Assessment under future audits could take the form of initial engineering design testing, followed by emissions testing in cases of non-compliance.
Results also indicate that the Australian/New Zealand standard for determining emissions from woodheaters, AS/NZS 4013, may require amendment to make it more difficult for engineering modifications to be made to woodheaters and to ensure that when woodheaters have been modified during testing to meet allowed emissions under the Standard, that these modifications form the basis for woodheater design when woodheaters are subsequently mass-produced.