Technical Report No. 4
Environment Australia, June 2002
ISBN 0 6425 4868 4
Early discussion of the significance of the growth in firewood use from 1978 in Australia occurred at the 'Fuelwood Cropping Investment Seminar' held in Melbourne in March 1981 and organised by the International Tree Crops Institute (Australia) (ITCI 1981). This seminar was important in that it brought together business and research organisations to discuss both industrial and residential use of firewood.
The Institute of Foresters of Australia (IFA 1983) organized the 'Firewood Forum' in Canberra in 1983. This Forum explored issues of firewood supply (Crane 1983, Groves 1983, MacArthur 1983, Turnbull 1983, Dal Piva 1983), woodheater design (Todd 1983a), popularity of woodheaters in the residential sector (Todd 1983b, Austin 1983) and the increasing problem of wood-smoke (Dunn 1983, Todd 1983b). Many of the problems associated with residential firewood use that are now widely recognized were aired at this Forum, although the general thrust of the Forum was relatively positive, i.e. suggesting that firewood was a desirable fuel.
Reviews, drawing on the experience of the United States and relating this to the Australian context, were also prepared, e.g. Emissions from Residential Wood Combustion Appliances: a Review of their Origin, Effects, nature and Measurement Techniques (Quraishi 1984).
Temporal changes in the number of households using firewood for space heating, water heating and cooking are available from occasional Australian Bureau of Statistics (ABS) surveys conducted nationally or in individual states. The ABS data span the period 1976 to the present. Other surveys have been conducted occasionally by state authorities or as part of research studies. Variation in survey questions about space heating means that not all data sets are compatible. The most common problem is that some surveys ask householders what the 'main' form of space heating is, some ask what the form of heating used in the main living area is, and some ask what heating appliances are in the household. The main form of heating and the heating used in the living area give comparable results, but asking what types of heating appliances are present grossly overestimates the importance of masonry fireplaces (e.g. ABS 1981). Many older homes have fireplaces that are never, or rarely, used. In some surveys information is sought on both main and secondary heating fuels/appliances. This provides the most detailed information on space heating.
The most useful national data set consists of
- ABS 1976 – main heating for 1976
- ABS 1983 – main and secondary heating for 1983, also water heating and cooking
- ABS 1987a – main heating for 1985/86
- ABS 1995 – main heating for 1994
- ABS 1999 – main heating for 1999, also water heating and cooking
Figure 2.2.1 summarizes the data set for Australia for the proportion of households using firewood as their main heating fuel, based on the above ABS publications. Fitting a fourth order polynomial to the data suggests a peak in popularity around 1992/93. The date of the peak may be an artifact of the curve fitting, but it is consistent with other information sources such as woodheater sales (AHHA 1999).
This data suggests that the proportion of households using firewood as their main heating source has dropped from about 18.5% in 1992 to 15.5% in 2000. This is a significant fall (about 3 percentage points or16% in relative terms). But when growth in the total number of households is included, the fall in the actual number of wood-burning households is much smaller, around 2% in relative terms. The annual decrease in the number of households using firewood as their main heating fuel is only around 3000 to 4000.
Figure 2.2.2, based on the same ABS surveys plus other data in each state, shows the trends in the proportion of households in each state and territory using firewood as their main heating fuel.
The graphs illustrate the relative importance of fuelwood in the residential sector in each state and territory. Tasmania has a significantly greater proportion of households using firewood than the other states. Western Australia's use is also high. The ACT is interesting, showing the greatest swing away from wood-fuelled heating, probably because reticulated natural gas was introduced in the late 1980s. Victoria, NSW and Queensland have shown the least decrease in the proportion of households selecting firewood as their preferred heating fuel.
Other surveys of household firewood use include the National Fuelwood Study, which conducted telephone surveys in five cities (Canberra, Hobart, Melbourne, Ballarat and Adelaide) and reviewed existing information on fuelwood use in other states and territories (Todd et al. 1989a). Various state surveys have also been carried out including:
- household energy sources, Tasmania (ABS 1975)
- residential energy use South Australia (ABS 1979)
- residential solid fuel use in SA (Kerby and Beer 1984)
- energy use in Victorian homes (SECV 1984)
- residential firewood use Tasmania (ABS 1987b)
Some of these surveys included discussion of the policy implications of increased firewood demand. For example, Kerby and Beer (1984) suggested that there was no need for government (Department of Mines and Energy) to change its involvement in firewood supply. It was felt that the existing supply system was relatively efficient and that demand was unlikely to outstrip supply. However, they did suggest a thorough review five years on. The report provided a comprehensive overview of firewood supply such as sources of firewood for the Adelaide region, who supplies it, how much consumers use, and the type of wood (80% hardwood logs, 10% softwood, 2% 'Mallee' roots, and 8% other). The question of air pollution is briefly raised as a matter requiring further study '… a detailed study of emissions from solid fuel heaters is necessary in order to monitor their contribution to air pollution' (Kerby and Beer 1984, p39).
The information from these surveys has been incorporated in various analyses of firewood demand and projections of heating preferences (e.g. Ferrier et al. 1985, Todd 1986a, Todd 1986b).
Estimates of firewood demand and total energy use in the residential sector require assumptions about the average firewood use per wood-using household. This introduces another layer of uncertainty into the equation. Several national and state surveys have sought information from householders about the quantity of firewood they use in one year (e.g. Todd et al. 1989a). However, there is some evidence that households that purchase firewood do not receive the weight that they assume they have paid for. Wall (1997) weighed 16 loads of firewood delivered in the Armidale region of NSW and found all were underweight, with an advertised 'tonne' actually weighing between 0.5 and 0.96t. A total of 26 'advertised tonnes' was, in fact, 19.9 tonnes or 23% underweight. If this is representative of other regions of Australia, it would mean that estimates of firewood use are significantly overstated. It is not known how widespread the practice of supply short-weight firewood loads is.
The estimates of total firewood use in Australia (about 4 million tonnes) presented in Section 1.2 are based on householder estimates of their annual consumption. Thus, they may have overestimated use by 23% or almost 1 million tonnes per year. However, more analysis of actual firewood use/delivery would be needed in order to firm up such estimates.
Driscoll et al. (2000), in their study of the ecological impact of firewood collection in Australia, estimated that household demand in 1999 was 4.5 to 5.5 million tonnes. This figure is slightly higher than the 4 million tonne estimate for 1999 given in Section 1.2. Driscoll et al. commissioned a national telephone survey of about 400 firewood-using households to collect information on firewood use. The agreement between the estimates is considered reasonable given the uncertainties in the two approaches.
The Australian Bureau of Statistics data show a clear change in heating preferences commencing around 1992/3 (see Figure 2.2.1). The proportion of households using firewood as their main heating fuel has dropped significantly. However, the increase in total number of households in Australia means that a relatively small decrease in the total number of firewood using households has occurred. The expected life of a woodheater (15 to 20 years) suggests that many heaters installed from the mid-1980s onwards will require replacement from 2000 onwards. This could lead to a more rapid fall in woodheater use because of growing public concern about wood-smoke and firewood collection. However, other factors such as increases in electricity or gas prices, or interruptions to supply could see a revival in woodheater use.
This Section provides an overview of national and state policies relating to the use of woodheaters and control of wood-smoke. This is followed by a brief description of Australian Standards for testing woodheaters.
As indicated below, it was only in the mid-1990s that wood-smoke was specifically targeted through state and federal policies (see also Todd 1996c). The need for such action was foreshadowed by several commentators a decade earlier (e.g. Quraishi 1986b, Quraishi 1988). A report commissioned by the National Energy Research, Development and Demonstration Council, The Impact of Woodheaters on Air Quality in Australia was published in 1989 (Todd and Singline 1989). This report recommended increased monitoring, household education programs on correct woodheater use and woodheater certification. These policy options were further refined and presented in the paper Policy Options for Reducing Smoke from Woodheaters (Todd 1998).
In 1990, the Heads of Government of the Commonwealth, States and Territories, and representatives from the Australian Local Government Association entered into the Inter-Governmental Agreement on the Environment (IGAE). The primary intention of the IGAE was to facilitate a more co-operative approach to the management and regulation of environmental issues between all levels of government and between jurisdictions.
Paragraph 2.2 of the IGAE confers the responsibility for facilitating the co-operative development of national environmental standards and guidelines on the Commonwealth government. To assist in the development of these standards, the Commonwealth government established the National Environmental Protection Council (NEPC) whose statutory objectives are to assist in ensuring that:
- people enjoy the benefit of equivalent protection from air, water or soil pollution and from noise, wherever they live in Australia; and
- decisions of the business community are not distorted, and markets are not fragmented, by variations between participating jurisdictions in relation to the adoption or implementation of major environment protection measures.
The functions of the NEPC under the National Environmental Protection Council Act 1994 and the corresponding Acts in each participating jurisdiction are to develop National Environmental Protection Measures (NEPMs) and to assess and report on the implementation and effectiveness of these NEPMs in participating jurisdictions. In accordance with the spirit of the IGAE, the NEPC Act provides that the primary responsibility for the implementation of all NEPM standards will remain the responsibility of the relevant jurisdiction. Hence, while the NEPC is responsible for the development of NEPMs in consultation with a variety of stakeholders, the Commonwealth government and each State and Territory government retains control over the implementation of the NEPM within those areas that fall within their respective jurisdictions.
The NEPC has the power to develop NEPMs in relation to a number of topics, one of which is ambient air quality. On 26 June 1998, the NEPC released the Ambient Air Quality NEPM (Air NEPM). The primary aims of the Air NEPM are to provide:
- nationally consistent ambient air quality standards; and
- nationally consistent ambient air quality measurement protocols.
It was hoped that by fulfilling these objectives, the Air NEPM would provide a nationally consistent air quality database for all major Australian air-sheds and assist in fulfilling NEPC's statutory objectives (NEPC 1998).
The national environmental protection standards established under the Air NEPM target six pollutants (carbon monoxide, photochemical oxidants (as ozone), lead, nitrogen dioxide, sulphur dioxide and particles) as the basis for the assessment of ambient air quality. Specific standards have been set for each of these pollutants and compliance with the NEPM requires all jurisdictions to evaluate its annual air quality performance against these standards. The goal of the Air NEPM is to achieve the specified standards in all jurisdictions by June 2008 (NEPC 1998).
As noted, one of the pollutants for which goals have been set under the Air NEPM is particulate material (PM10). It is the only chemical non-specific pollutant included in the Ambient Air Quality NEPM. It is also the pollutant most relevant to this review of air toxics. A National approach to measurement and calibration of particulates, through common operating protocols, was proposed in 1999 (Richardson and Crerar 1999).
The type and nature of particles differ considerably. These differences include size (as measured in terms of particle diameter), source, formation, chemical composition, and physical characteristics. However, the goal established under the Air NEPM concentrates solely on the size of airborne particles. In this regard, the goal set under Schedule 2 of the Air NEPM for PM10s is a calendar day average of 50 µg/m³ (microgram per cubic metre). The Air NEPM goal is to have a maximum of 5 exceedence-days each year by June 2008.
This standard is generally consistent with, or lower than, particulate pollution standards set in other developed nations. The particulate standards in the United Kingdom, European Union and California are all the same, or very similar, to the Air NEPM particulate standard. The US National Ambient Air Quality Standard for particulates is a 24-hour average of 150 µg/m³ while the equivalent Japanese standard is a 24-hour average of 100 µg/m³ (NEPC 1998).
The national environmental protection protocol of the Air NEPM requires the measurement of the six listed pollutants to occur at 'performance monitoring stations' that must be sited in accordance with the requirements of the Australian Standard AS2922-1987 (Ambient Air-Guide for Siting of Sampling Units). This standard requires the performance monitoring stations to be located in positions that provide an 'average' representation of:
- the general air quality in the airshed; and
- the exposure of the general population to these pollutants.
Further, section 13(2) of the Air NEPM explicitly requires performance monitoring stations to be located, 'in a manner such that they contribute to obtaining a representative measure of the air quality likely to be experienced by the general population in the region or sub-region' (NEPC, 1998). Compliance with the Air NEPM requires the relevant jurisdictions to adhere to the terms of the monitoring protocol when assessing whether air quality meets the NEPM standards (NEPC 1998).
The Air NEPM requires the establishment of a Peer Review Committee to provide advice to the jurisdictions in preparing and applying monitoring plans. In assessing jurisdictional monitoring plans, the Committee is required to consider whether the performance monitoring stations have been sited in appropriate locations in accordance with the terms of the Air NEPM protocol and the Monitoring Standard. Each participating jurisdiction has until June 2001 to establish monitoring procedures and to commence assessment and reporting in accordance with the terms of the Air NEPM.
The first periodic review of the NEPM was started in May 2001 with the release of an Issues Paper addressing the need for a PM2.5 Standard to replace or supplement the PM10 Standard set in 1998 (NEPC, 2001). The Issues Paper reviews the state of knowledge about particle levels in Australia and the health effects of particles of various sizes. It points out that domestic solid fuel heaters contribute a large percentage of total PM2.5 particles and strategies aimed at lowering the levels of these finest particles would inevitably involve more attention on domestic woodheaters. The NEPC suggests multiple possible monitoring strategies: using PM10 as a surrogate measure of PM2.5, using a PM1 standard, considering adopting overseas PM2.5 standards and looking at various ways of measuring PM2.5 including nephelometry. The Issues Paper explores various methodologies for setting a standard such as health risk assessment and expert panels. The Issues Paper was open for comment for one month. The NEPC will now revise the Issues Paper based on this feedback, conduct a series of workshops and further review and then consider starting a PM2.5 Standard through the official statutory review process.
The Federal Government is developing an amendment to the Building Code of Australia addressing proper installation of woodheaters. The AS4013 standard for the manufacture and testing of woodheaters was implemented in 1992 and updated with stricter emissions levels in 1999. This standard and the application in each state and territory are addressed in detail in State legislation below and in Section 2.6.
The Federal Government has also sponsored the $16 million Air Pollution in Major Cities Campaign, which is administered by the Natural Heritage Trust. This campaign aims to reduce the six major pollutants identified in the NEPM for Ambient Air Quality through a range of national educational projects. The campaign focuses on the regions with the worst domestic wood-smoke problems: Tasmania; Adelaide and Mt. Gambier; Perth and South-West Western Australia; Canberra; Shepparton, Bendigo, Ballarat and Gippsland in regional Victoria; Albury, Tamworth, Orange, Dubbo, Wagga Wagga, Goulburn, Cooma and Queanbeyan in New South Wales; Toowoomba and Maroochydore in south-eastern Queensland; and Alice Springs. An educational campaign, 'Breathe the Benefits', is designed to disseminate correct instructions for woodheater use. Other educational programs under the 'Major Cities' campaign include Air Watch and Smogbusters.
An Independent study of Urban Air Quality in Australia released in 1997 recommended that all States and Territories adopt uniform legislation and coordinate policies with respect to standards, community education, and controls on the sale of firewood (AATSE, 1997). One section of this study dealt specifically with residential sources of air pollution, including wood-smoke (Todd et al. 1997), setting out options for addressing the wood-smoke problem. In 'Clear the Air' the Government responded to the AATSE study and set out a timeline for addressing actions under its domain while encouraging all States and Territories to conform to uniform approaches (Commonwealth of Australia 1998).
This Section reviews policy documents and legislation related to air pollution and residential wood-smoke emissions in each State and Territory.
In 1989 the Legislative Assembly for the Australian Capital Territory initiated a series of investigations into the use of woodheaters in Canberra because of concerns about firewood supply and air quality (SCCHE 1991a,b). The Standing Committee on Conservation, Heritage and Environment prepared a set of 26 recommendations dealing with further studies, community education, fuelwood plantations, wood-smoke monitoring, improved thermal performance of houses, incentives to upgrade older heaters or change to other heating fuels and investigations into replacing some hardwood with softwood firewood.
In the years since Environment ACT and the ACT Government have formulated a number of regulations aimed at minimising pollution from domestic woodheaters. The Environment Protection Act 1997 instituted a 'general environmental duty' which means that individuals must take all practicable and reasonable steps to prevent or minimise environmental harm or environmental nuisance from activities they conduct. (ACT Government 1997a,b). In addition to this general duty, the Act called up the AS4013 standard for new or used woodheaters sold in the ACT. More recently, the sale of firewood has been regulated as a new Firewood Industry Code of Practice was made into law via amendments to the Act in 2000. Environment ACT has designed a fact sheet on air pollution from domestic premises which explains the Act (Environment ACT 1997) and in June 2001 began a major community education campaign entitled 'Don't Burn Tonight'.
The 1997 Act stipulates that a person shall not sell a woodheater unless it complies with AS4013 standard and it holds a certificate of compliance issued by a person or body authorised by the Authority. The ACT did not set up its own certificate system, but accepts the National Certificates from the two national energy centres approved under the AS4013 Standard. The language of the Act refers to maximum emissions specified in section 7 of the AS4013, so the newest AS4013 (1999) standards have automatically been adopted. The restriction applies to all sales (new and used woodheaters).
The Act also makes altering or removing a compliance plate an offence and specifies that anyone selling equipment for use on residential premises, or installing solid fuel-burning equipment on residential premises shall not altar the structure, air inlet, exhaust system or a part of the equipment involved in combustion.
The government of the ACT regulated the supply of firewood under an amendment to the EPA legislation (ACT Government 2000). The amendment to the Act adds the 'sale or supply, or cutting, storing or seasoning firewood in preparation for sale or supply' to the list of activities requiring environmental authorisation. As of 31 May 2000, anyone involved in these activities must acquire an authorisation by applying, paying a fee and submitting to public consultation and posting in a daily newspaper.
The criteria for authorisation are spelled out in the amendment to the Regulations (ACT Government 2000, original regulations are ACT Government 1997b). Authorisation may be awarded only to sellers or suppliers of firewood in the ACT who: (a) as far as possible, offer customers the choice of mixed wood loads; (b) supply wood by mass (weight) only and not by volume; (c) provide information on the weight of the load, the proportion of hardwood to softwood, the source and type of the wood and correct burning practices and (d) supply seasoned firewood only.
This amendment to the regulations was based on the Firewood Industry Code of Practice 1999 developed by ACT Solid Fuel Industry Working Party, a delegation of industry and trade organizations, consumer rights groups, government departments, and conservation groups (ASFIWP 1999). This Code of Practice was developed not only in the interest of minimising environmental harm, but also in providing consumer protection and allowing consumers to make informed choices. The specific environmental aim was to reduce the use of hardwood species in firewood, especially boxwoods.
The Code discusses the definition of seasoned wood (which was left undefined in the EPA Amendment). The Code does not specify a maximum moisture content for seasoned wood because of 'uncertainties associated with use of hand held moisture meters and because the moisture content of wood which is properly seasoned may vary between species' (ASFWIP 1999). It does set an 'indicative' measure of 20% and states that 'firewood merchants will use their experience and judgement to ensure that they only sell seasoned wood' (ASFWIP 1999). Merchants must be prepared to back up their decisions to Environment ACT if questioned. The Code also arranges for collection of information about the firewood industry and amount and types of firewood sold in the ACT. Merchants who agree to follow the Code supply the Environment ACT with information about the amount of hardwood and softwood sold and Environment ACT collates this data and gathers other data on complaints about smoke from domestic chimneys.
In addition to the Act and associated legislation, the Environment ACT released an Environment Protection (Air) Policy in 1999 (Environment ACT 1999). This Air EPP is not legally binding, but rather describes the relevant legislation and gives an indication of 'general environmental duty' in terms of ambient air quality and emissions. The Air EPP identifies transportation and fires from non-industrial activities as major sources of emissions in the ACT. As part of the effort to encourage better domestic fire management, the Air EPP spells out ways in which people can meet their environmental duty including using plenty of dry kindling and providing sufficient air flow, especially in older non-4013 compliant heaters, and storing firewood under cover. The state of the environment report on the Environment ACT web site notes that the department is conducting random 'inspections' of smoky chimneys. Inspectors will stop by and leave educational information if they see a smoky chimney, but are not giving out fines or penalties (Personal Communication, David Power, Environment ACT).
In June 2001 Environment ACT launched a new community education program, 'Don't Burn Tonight'. This program is similar to the 'Don't Light Tonight' campaign in NSW. It encourages people to use alternative heating on nights when poor dispersion is expected due to cold, still weather by announcing 'Don't Light' nights through the popular media (Environment ACT 2001). In addition to this campaign for householders, the ACT government is organising an education campaign for firewood wholesalers (Environment ACT 2000).
The ACT has begun monitoring ambient air quality in accordance with the NEPM PM10 standard, but 24-hour measurements are only taken once every six days in Canberra. Even so, PM10 levels exceed the NEPM limits occasionally and particles have been named a 'pollutant to be watched' (Environment ACT 2000). Levels are expected to exceed more days each year when continuous monitoring is started. The ACT suffers from excessive pollution due to temperature inversions, which trap particles during still, cold winter conditions. A few local areas experience intense problems, including the Tuggeranong Valley, which was studied by Environment ACT in 1995 (Environment ACT 1995).
The Environmental Protection Authority (EPA) released a Paper on Air Pollution from Solid Fuel Home Heaters in 1996 (EPA NSW 1996). The EPA hoped to inform decision making at the local council level and encourage feedback about tactics for reducing wood-smoke pollution. The paper reviewed research on wood-smoke emissions and community attitudes in NSW and outlined possible tactics including legislation, community education and codes of practice for heater installation.
In 1997 the Government of New South Wales adopted the AS4013 standard for woodheaters via the Clean Air (Domestic Solid Fuel Heaters) Regulation of 1997 (NSW Government 1997). A 2000 amendment to this regulation has incorporated the newest 1999 AS4013 standard. As of 5 July 2001 it is illegal to sell a new woodheater in NSW that does not meet the 1999 emissions standards and carry a metal plate stating compliance. The regulation applies to all woodheaters except: masonry appliances built on site, central heating appliances, cooking stoves, appliances intended solely for heating water and appliances intended solely for distributing heat through ducts. The regulation does not control the sale of used woodheaters.
The Clean Air Regulation (CAR) is in force under the Protection of the Environment Operation Act 1997 and is administered by the EPA. It requires that all applicable woodheaters be marked with a metal plate specifying the manufacturer, date of manufacture, and 'compliance with AS4013' or 'exemption from compliance with AS4013'. The onus for proving compliance lies with the manufacturer who must apply for either a Certificate of Compliance or a Certificate of Exemption for each model line. Certificates of Exemption may be issued if the woodheater cannot be tested by the methods described in the AS4013 standard (EPA NSW 1997).
The CAR devotes detailed mention to woodheaters fitted with catalytic converters. These woodheaters must meet a stricter emission standard (2.25g/kg instead of the normal 4.0g/kg) and come with a guarantee for the catalytic converter. The CAR also assigns random testing and certificate award and cancellation powers to the authority (EPA NSW 1997).
In addition to legislating woodheater standards, the NSW government has developed a broad 'Action for Air' policy framework for improving air quality throughout the Illawarra and Lower Hunter regions (EPA NSW, 1998). This framework addresses all types of air pollution but focuses on six key objectives, one of which is promoting cleaner homes. The two strategies for cleaner homes are 1) reducing emissions from solid fuel heaters and 2) improving energy-efficiency of homes. The actions toward reducing heater emissions include: ensuring compliance with the CAR, developing a code of practice for heater installation, conducting community education programs on heater use and continuing the 'Don't Light Tonight' campaign.
Since the release of the Action for Air in 1998 the EPA has developed a code of practice entitled 'Guidelines for Selecting, Installing & Operating Domestic Solid Fuel Heaters' (EPA NSW 1999). This guideline is designed to help local councils understand their role and responsibility in decreasing pollution from woodheaters. Under 1998 amendments to the Environmental Planning and Assessment Act and the Local Government Act, local councils are responsible for approving the installation of woodheaters and associated building work. In addition councils can issue orders under the Local Government Act 1993 to ensure people use their woodheaters in a healthy and safe manner and the EPA can fine people $320 for using solid fuel heaters 'in an environmentally unsatisfactory manner' (EPA NSW 1999).
The 'Don't Light Tonight – Unless Your Heater's Right' campaign alerts the public via mass media on nights when poor dispersion is expected due to cold, still weather and encourages the use of alternative heating. Other community education programs include a web site devoted to reducing pollution from wood-smoke and a council resource kit for local education.
In 'non-metropolitan areas' of NSW wood-smoke is a major wintertime pollutant and local-state cooperation has resulted in effective air quality management in some areas. In Armidale, where measured wood-smoke levels are high (Roberts and Lin 1998), the 'Clean Air Campaign' has encompassed community education and development of a local air pollution index. The Armidale Clean Air Campaign (in association with the local council) is considering issuing fines to repeat smoky chimney offenders.
The government of NSW commenced regular monitoring of PM10 particles in Sydney in 1988 and now monitors PM10 particles at six sites in metropolitan Sydney, three sites in the Lower Hunter and four sites in Illawarra.
Pollution from wood-smoke is a large concern in the Northern Territory, but the vast majority of this smoke is from bushfires and grassland burning; domestic solid fuel heaters rank as a small source of emissions. Nevertheless, solid fuel heater emissions were studied as part of a survey carried out by the Victorian EPA for the Northern Territory Department of Lands, Planning and Environment (DLPE) in March 2000. Solid fuel heaters are rare in Darwin, but in Alice Springs 25% of households surveyed used solid fuel heaters and all of these were woodheaters. Seventy per cent of these woodheaters were the slow combustion type and seventy per cent of the slow combustion heaters were AS 4013 compliant manufactured after 1993 (EPA VIC 2000b).
In the Northern Territory Monitoring Plan for NEPM Ambient Air Quality Standards, the DLPE identified bushfire smoke as 'the most significant pollutant in the Darwin region' (DLPE 2001). This conclusion is based on the correspondence between exceedences of the PM10 level and visible regional bushfire smoke. In terms of overall air quality policy, the Environment & Heritage Division released a five-year 'Strategy for Waste Management and Pollution Control in the NT' in September 1995. One of the actions in this plan was the development of an air quality management strategy, which would address the Air NEPM goals and propose appropriate legislation. The final report on the strategy (EHD 2001) notes that the Air NEPM was adopted under the Waste Management and Pollution Control Act 1999 and the Monitoring Plan (DLPE 2001) was near completion. The report also states 'a broader policy framework will be pursued following implementation of the Monitoring Plan' (EHD 2001).
In the Environmental Protection (Air) Policy 1997 (Air EPP) the Government of Queensland adopted the AS4013 standard for any (new or used) solid-fuel burning equipment sold for use in residential premises (Queensland Government 1997). The Air EPP applies within the legal framework of the Environmental Protection Act 1994 and the Environmental Protection Regulation 1998 and is administered by the Environmental Protection Agency.
Queensland did not create its own certification system for woodheaters, but instead accepts certificates of AS4013 compliance from the South Australian Energy Information Centre. The Air EPP requires plates with manufacture and compliance details are fitted to every woodheater sold in the state. It further defines tampering with such a plate or the woodheater itself as an offence.
The Air EPP also sets up complaint and dispute resolution procedures for the 'unreasonable release of contaminants' (Queensland Government 1997) into the environment, which cause 'unlawful environmental harm' or are offensive to others. An abatement notice can be issued to someone releasing such contaminants.
In addition to legislation on woodheater compliance and nuisance smoke, Queensland has developed the South East Queensland Regional Air Quality Strategy (SEQRAQS) that was released by the EPA in 1999 (EPA QLD 1999). The southeast region was chosen because it is much more densely populated than the rest of the state, with 60% of present population, and is expected to experience rapid population growth. The region includes 18 local government areas extending from Noosa in the North, to Beaudesert and the Gold Coast in the South, and from the Moreton Bay Islands in the East to Toowoomba in the West.
The air quality in southeast Queensland is presently quite good and the SEQRAQS aims to prevent deterioration with the expected population growth. Because pollution from solid fuel heating is the most significant domestic source, the SEQRAQS suggests enforcement of Australian installation and emissions standards AS3869, AS2918 and AS4012, in addition to AS4013 that is already in place. Further planned actions include: encouraging adoption of chimney/flue height standards into the Australian Building Code, investigating incentive schemes for switching fuels or upgrading woodheaters and developing and distributing guidelines for correct woodheater installation and use. In addition to these efforts, the SEQRAQS sets a goal for low polluting (e.g. solar) hot water generation to comprise 20% of the total by the year 2011.
The EPA monitors air quality under NEPM standards at fifteen stations in southeast Queensland. Results have shown that all pollutants have been fairly steady over the last 10 years and are generally within the NEPM guidelines.
The study of residential solid-fuel use in South Australia by Kerby and Beer (1984) did not identify air pollution as a serious concern. The study suggested new technology should keep any problems at manageable levels; '… a trend towards more efficient appliances may mean less air pollution. In particular, stoves which produce secondary combustion, through either pre-heating incoming air or using a catalyst, achieve almost complete combustion, and may add few contaminants to the air.' (Kerby and Beer 1984, p. 22)
The South Australian Department of Environment and Planning carried out a survey of local councils in 1987, seeking their views on the issues of back-yard incineration and residential woodheater use. The feedback from local government and the Department's recommendations concentrated on the issue of flue height in order to minimise the local problem of neighbour polluting neighbour (DEP SA 1987). It was suggested that legislation might be introduced to require covered storage of firewood. The Department also recommended development of an Australian standard for emissions from woodheaters. The AS4013 standard has since been implemented and updated, but the legislation to require AS4013 compliance in South Australia was stalled because of problems related to the Mutual Recognition Agreement (trade between states). Now that AS4013 standards have been adopted in most other jurisdictions, the EPA is again trying for similar legislation in South Australia.
The Environmental Protection Act 1993 (the Act) introduced a number of legislative tools including Environmental Protection Policies (EPP). An EPP can be made for any purpose directed towards securing the objects of the Environment Protection Act. This may include both mandatory and voluntary provisions.
A number of EPPs were set up immediately to replace legislation repealed by the Act. One of these transitional EPPs deals with burning policies and prohibits the use of firewood treated with copper-chrome-arsenate or other chemical preservatives. (DEP SA 1994a) Another transitional EPP deals with Air Quality. This EPP sets emission levels for industrial chimneys and boilers but does not explicitly address domestic woodheaters (DEP SA 1994b).
Environmental Protection Authority (EPA) discourages the use of open fires for domestic heating and the use of older woodheaters that do not meet the Australian Standard and is actively engaged in raising public awareness of the need to protect urban air quality. The EPA is currently developing a paper on domestic solid fuel heaters outlining actions and responsibilities related to current and future legislation (Personal Communication, Tom Whitworth, Manager Atmosphere and Noise Strategy Branch, EPA).
The EPA monitors ambient air quality at fourteen sites in the Adelaide metropolitan area, and operates additional stations in the Spencer and Southeast air-sheds.
Levels of particulate pollution in parts of Tasmania are well above the national standard (DPIWE 2000c) with PM10 levels in Launceston outstripping the NEPM standards one out of three days in winter (DPIWE 2000a), although significant improvements have recently been observed (see below). The main source of these PM10 particles is domestic solid fuel woodheaters and open fireplaces.
In 1993, Tasmania introduced the Environment Protection (Domestic Solid Fuel Burning Appliances) Regulations. These Regulations called up the Australian Standard AS4013, requiring any appliance model-line manufactured, or imported for sale, in the State to hold a certificate demonstrating the emission factor is not greater than 5.5 g/kg (or 3.0g/kg if fitted with a catalytic converter). The Regulation does not make it an offence to modify an appliance, nor does it restrict the sale of second hand appliances (built before 1993) that do not hold a certificate. Exempted woodheaters include any that are: built on site and used as open fireplaces, used for central heating used to produce heat for distribution through ducts or used solely for cooking or heating water (Tasmania Government 1993).
Because the numerical standard (5.5g/kg) for emissions was written into the regulation, the stricter AS4013 standard introduced in 1999 has not been incorporated into Tasmanian law. Best guess estimates for the state are that only 30-40% of woodheaters now in residences are AS4013 compliant (1993 Standard) and that there has been no serious attempt to enforce the standard (DPIWE 2000a). The 1993 regulation instituted a system of certification at the state level, very similar to that instituted in New South Wales; the onus of applying for certification is on the manufacturer and the state authority can issue certificates of compliance or exemption.
In January 2000 the Department of Primary Industry, Water and Environment (DPIWE) began the process of developing an over-arching Air Policy with the release of a Discussion Paper on Air Quality Management and Policy Development (DPIWE 2000a). Following a period of public comment DPIWE released a response addressing issues raised in written submissions (DPIWE 2000b) which formed the basis for a Proposal for a Draft Environmental Protection Policy (EPP) (DPIWE 2000c). An approved EPP becomes a statutory document under the auspices of the Environmental Management and Pollution Control Act 1994. It can therefore be used both as a regulatory and general policy instrument.
The proposed EPP will form an umbrella policy covering the regulation of woodheater, fuel and ambient air quality standards. The basis for the EPP will be the Response to Public Comments on the Discussion Paper on Air Quality Management and Policy Development that cites a number of ways that the present AS4013 compliance system should be changed. These recommendations include:
- revising the emissions limit to match the AS4013 standard instead of instituting the present numerical value;
- substituting the state certification system with National Certificates from the Energy Information Centre;
- prohibiting the installation of pre 1993 woodheaters;
- requiring all new installations to be AS 2918 compliant and prohibiting the modification of woodheaters;
- capping the moisture content of firewood for sale and prohibiting the use of wet wood in woodheaters and fireplaces; and
- empowering state and local officials to conduct audits of woodheater and firewood suppliers.
In September 2001 the Draft Environment Protection Policy (Air Quality) and Regulatory Impact Statement was released for public comment (DPIWE 2001a). The Policy includes several new initiatives to address wood-smoke including making it an offence to allow visible smoke from a woodheater of fireplace to come into contact with another residential building for a continuous period of two minutes or more.
DPIWE also suggests other strategies such as community education, development of a Code of Practice for woodheater installation, a buy-back scheme, smoke patrols and air quality forecasts for possible consideration (DPIWE 2000b). In July 2001, the Federal Government, as part of its Air Pollution in Major Cities Program, announced a grant of $2.05 million to support such a program in Launceston (Newman 2001).
The monitoring of ambient air quality for NEPM standards is ongoing at one station Hobart and one station in Launceston. Particles, principally due to emissions from domestic woodheaters in winter, are the only ambient air pollutant of high concern. The results of monitoring from 1999/2000 show that the annual average PM10 concentration in Launceston has decreased 30% since 1992/1993 and the number of exceedences of the NEPM standard has decreased 43% over the same period (DPIWE 2001b). The Tasmanian Air Quality Management plan has been approved by the NEPC and new monitoring stations will be placed around the state over the next few years.
Particulate pollution is a major concern in Victoria, especially in Melbourne, and woodheaters are significant contributors to particle levels. It is estimated that domestic wood combustion contributes around 60% of PM10 emissions and 68% of PM2.5 emissions in Port Phillip Region in the cooler months of the year (EPA VIC 2000a). Present legislation is under development that will enforce the AS4013 standard for woodheaters sold in the state and outlaw installation of non-certified woodheaters (personal communication, Krista Milne). Victoria and South Australia are the only states that do not yet require that new woodheaters comply with the emission standard AS4013.
In addition to encouraging the passage of this legislation, the Environmental Protection Authority (EPA) has developed a series of policy documents through research and community consultation. These include the Draft Air Quality Improvement Plan: Port Phillip Region (AQIP) released in July 2000 (EPA VIC 2000a) and an announcement of a review of the State Environmental Protection Policy (Air Quality Management) in December 2000 (EPA VIC 2000c). Both of these documents address pollution from domestic solid fuel heaters and suggest a variety of strategies. Other relevant documents include an exploratory paper on air quality management and an air emissions inventory for the Port Phillip Region (EPA VIC 1997 and EPA VIC 1998) as well as the Melbourne Mortality Study (EPA VIC 2000d).
The AQIP summarises present actions and outlines future possibilities for Melbourne, Geelong and Western Port. The AQIP names wood-smoke from residential sources as a priority concern and outlines two main areas for future improvement: 1) improving the standard of woodheaters and installation and 2) promoting practices which reduce woodheater emission rates. Besides encouraging legislation to enforce the AS4013 standard, the AQIP suggests changes to the Building Code of Australia relating to installation of woodheaters and endorses Queensland's suggestion of flue height requirements related to the heights of surrounding structures. The AQIP also suggests development of a Firewood Industry Code of Practice such as that in place in the ACT (EPA VIC 2000a).
Other initiatives under consideration include 'change-out' programs, community education on correct heater operation and improving media coverage of voluntary curtailment program during periods of high air pollution ('smog alert days'). The AQIP also encourages empowering local governments to control nuisance smoke.
The review of the State Environmental Protection Policy (Air Quality Management) (SEPP (AQM)) suggested steps toward empowering local officials. The proposed framework of local environmental stewardship keyed on Neighbourhood Environment Improvement Plans (NEIP). Local groups can develop these NEIPs on a voluntary basis, but if pollutants are measured in a community above set 'trigger levels' than a local plan must be established (EPA VIC, 2000c).
A separate act of legislation, the Environment Protection (Livable Neighbourhoods) Bill, passed into law in March 2001. This legislation adopted many of the suggestions from the review of the SEPP (AQM) including assigning a shared environmental responsibility and setting up a local intervention system.
Victoria adopted the NEPC air quality standards as state law with the passage of the State Environmental Protection Policy (Ambient Air Quality) 1999 (Victoria, Government 1999) and its Air Quality Monitoring Plan was the first state plan approved by the NEPC in May 2001. The EPA is now monitoring PM10 levels at ten stations in Melbourne, two stations in the Latrobe Valley and one at Bendigo.
In 1997 the Western Australian government began a four-year process of developing a Perth Air Quality Management Plan (PAQMP). Discussion papers on open burning (Tubby 1997a) and smoke emissions from home heating with firewood (Tubby 1997b) were released for comment. At various stages in this process the Government of Western Australia passed relevant regulations and the resulting plan builds on this present legislation to map out a strategy for the next thirty years.
In dealing with wood-smoke pollution, the PAQMP focuses on enforcement of the Environmental Protection (Domestic Solid Fuel Burning Appliances and Firewood Supply) Regulation 1998. This regulation adopts AS4013 standard for new and used woodheaters sold in Western Australia and prohibits the sale of firewood with greater than 20% internal moisture content (Western Australia Government 1998a). It also prohibits the sale of firewood that has been painted, coated with plastic, or treated with copper-chrome-arsenate.
The AS4013 standard applies to all woodheaters sold as individual appliances, but does not apply to woodheaters 'installed in and sold together with' (Western Australia Government 1998a) a building. The legislation includes a grandfather clause for woodheaters, which met the AS4013 standard that was in place when they were tested and delegates authority to inspectors of the woodheater retail industry. The legislation also clearly defines marking or selling a woodheater which does not meet standard as a punishable offence if the person knows 'or ought reasonably to have known' (Western Australia Government 1998a) that the appliance was substandard.
The prohibition on the sale of green firewood is limited in geographical area to the districts of Wanneroo, Swan, Mundaring, Kalamunda, Armadale, Serpentine-Jarrahdale and Mandurah and does not apply to wood sold to a firewood wholesaler or retailer. The Regulation stipulates that retailers and wholesalers must clearly label green firewood as not for sale and store it away from dry wood. It also sets up a system whereby people holding special permits may sell wood with a greater than 20% moisture content. The Chief Executive Officer issues and sets the terms of these permits.
This domestic woodheater and firewood regulation came out of the PAQMP development process that began in 1997 as a pre-emptive effort to preserve Perth's high air quality in the face of increasing development and population growth. The first stage in the process was a report by a Select Committee on Perth's Air Quality (SCPAQ 1998). This document and the Government's response (Western Australia Government 1998b) outlined the basic strategies for the formulation of a final policy. The DEP released a draft PAQMP in June 2000 (DEP WA 2000a) and the final policy in December 2000. This final PAQMP draft names haze caused 'mainly by domestic wood-burning heaters' (DEP WA 2000b) as a major problem in winter.
The plan suggests a number of strategies for cutting down wood-smoke. These include: adopting the newest AS4013 standard, updating the building code to include proper woodheater installation, operation, and repair and developing an accreditation course for woodheater installation based on this new code. The PAQMP also suggests changes in legislation to increase the enforcement powers of local officials and enhance awareness of the firewood legislation among wood suppliers. A research project into incentive programs discouraging woodheater use is also proposed.
In addition to focusing on cutting down wood-smoke production, the PAQMP deals with monitoring particulate levels in ambient air. PM10 particulate levels are presently monitored in the Perth area and generally meet the NEPM goals.
In response to concern from fire authorities, the insurance industry and academics about safety and air pollution, the Standards Association of Australia (SAA), now Standards Australia, established a committee to prepare a series of Australian standards for residential solid-fuel burning appliances – Committee CS/62. The Committee first met in 1983 and determined its first priority should be to prepare a standard for the safe installation of solid-fuel burning appliances.
Between 1978 and 1984, when the number of woodheater installations in Australia were increasing rapidly, building inspectors were recommending that installations should comply with the installation standard for oil burning heaters, AS 1691. The higher flue temperatures, more corrosive combustion products, and higher heat outputs from woodheaters meant that the oil heater installation standards were totally inadequate. A study of house fires in Tasmania from 1980 to 1983 indicated one house fire per year attributed to a woodheater for every 1000 heaters in use (Todd et al. 1985). When the draft Standard was released for public comment in 1984, it was rapidly adopted as the safest method of installation even though it had not been formally published.
The Standard AS 2918-1987, 'Domestic solid fuel burning appliances – Installation' (SAA 1987) adopted the usual practice for standards of this type in providing both performance based options and 'deemed to comply' options based on worst case situations (Todd 1987). The Standard applied to woodheaters, slow combustion cooking stoves, solid-fuel water heaters and solid fuel furnaces. It did not apply to masonry open fireplaces. From a practical installation perspective, the Standard meant that all manufacturers of solid-fuel burning residential appliances would have to have their installation requirements checked by a registered laboratory. The test procedure specified in the Standard included verification that minimum installation clearances for the appliance and flue were adequate and that sufficient protection for the floor under and around the appliance was provided. Two test regimes were required, one for 'normal' high fire operation and one for 'flash-fire'. Testing was to be carried out using air-dry Pinus radiata timber. A softwood species was chosen because softwoods were shown to give higher temperatures in the appliance and flue than hardwoods. In the high fire test, fuel is added every 10 minutes at the maximum rate the appliance will burn. The test is continued until all temperatures have stabilised at their maximum values. Temperatures on test enclosure walls, ceiling and floor must not exceed specified limits. The flash fire test requires removal of half the burning fuel load from the appliance while it is at its maximum temperature and filling the firebox with fresh fuel, then leaving the refuelling door ajar, opening ash removal doors or any other adjustment to give maximum heat conditions for the duration of this one burn cycle.
The Standard also set minimum height requirements for the appliance flue. These were aimed at safety issues, not smoke dispersion.
A second edition of the Standard was published in 1990 (Standards Australia 1990). The second edition included some revision of the 'deemed to comply' conditions as a result of experience gained in test laboratories (worst case conditions were made tougher, i.e. greater clearances) together with some other minor changes.
The Standard was called up in building regulations around the country, greatly reducing the risk of house fires associated with these appliances.
The design and construction standard for residential solid-fuel burning appliances was first published in 1991 as AS3869-1991. It was revised in 1999, creating a joint Australian/New Zealand Standard, AS/NZS 3869:1999 Domestic solid fuel burning appliances – Design and construction. The Standard specifies materials (e.g. the type of steel and thickness) for various components of solid-fuel burning appliances based on the maximum temperatures reached during a specified test process. The aim of the Standard is to ensure the durability of the appliance.
This standard has not been called up in any Australian legislation (i.e. it is purely voluntary). No manufacturer has had any appliance model tested to this Standard by NATA registered laboratories. However, the Standard is widely used by manufacturers when designing new models as a guide to materials and components. In practice, the durability of woodheaters appears good, with an average lifetime of 15 to 20 years.
The performance test method standard was first published in 1992 as AS4012-1992. It was revised and published as a joint Australian/New Zealand Standard in 1999, AS/NZS4012:1999 Domestic solid fuel burning appliances - Method for determination of power output and efficiency. The Standard provides a test method, using a calorimeter room, for accurate measurement of heat output rate (power) and efficiency of residential solid-fuel burning heating appliances. The Standard specifies design parameters, measurement accuracy and calibration procedures for a calorimeter room. It also specifies a 'real-world' fuel and operating procedure for the appliance.
The Standard was developed in response to industry and consumer group requests for a standard method of measuring and reporting appliance performance. The Standard measures and requires reporting of the total efficiency, which is the product of the combustion and heat transfer efficiencies. Also, the Standard requires labelling of the appliance with the average efficiency measured at high, medium and slow burn rates and the average heat output rate for the high burn rate cycle. This Standard is indirectly called up in State legislation because it is an integral part of the emission standard.
The emissions test method standard was first published in 1992 as AS4013-1992. It was revised and published as a joint Australian/New Zealand Standard in 1999, AS/NZS4013:1999 Domestic solid fuel burning appliances – Method for determination of flue gas emission. The Standard provides a test method, using a dilution tunnel, for accurate measurement of particulates emitted by residential solid-fuel burning heating appliances. The Standard specifies design parameters, measurement accuracy and calibration procedures for a dilution tunnel that must be operated in conjunction with a calorimeter room. Emission testing can be carried out simultaneously with performance testing.
The Standard applies to solid-fuel burning space-heating appliances (including those fitted with water heating devices). It does not apply to masonry fireplaces, cooking stoves, central heating appliances or water-heating-only appliances. Nor does it apply to heating appliances that have heat output rates greater than 25 kW or appliances where the carbon dioxide concentration in the flue at high burn rates is less than 5% by volume. These last two exceptions relate to the difficulty in carrying out tests in the laboratory, rather than any suggestion that emissions from these appliances are less significant.
The Standard includes an upper limit for acceptable particulate emissions of 4 grams of particles per kilogram (oven-dry weight) of fuel burnt. This emission factor was reduced from 5.5 g/kg (in the 1992 Standard) to 4 g/kg at the request of pollution control authorities. The decision to set the maximum allowable emission as an emission factor, rather than emission rate (g/h), was made so that the emissions during slow burning carried more weight in the overall average emission factor. The choice of emission factor or emission rate is not a trivial issue (Tiegs 1995a).
The emission Standard has been called up in legislation in most Australian states and territories (see Section 2.3.2). The legislation varies from state to state, but generally it applies at point of sale (i.e. it is not retrospective).
In developing the test method adopted in the Standard a series of inter-laboratory tests were conducted (Todd et al. 1989b). Testing at the Home heating Laboratory, University of Tasmania and Amdel in South Australia demonstrated that good agreement was possible between the laboratories (within ± 4%) provided wood parameters were carefully controlled.
The test fuels standard, AS/NZS4014:1999 Domestic solid fuel burning appliances – Test Fuels, has five parts each dealing with a test fuel used in the performance and emission test standards. The standard sets the acceptable range for physical parameters of each fuel type for use in the appliance testing. Parameters such as density, moisture content, calorific value, and piece size are specified. The five parts of the standard cover: hardwood, softwood, lignite briquettes, sub-bituminous coal, and semi-anthracite coal briquettes. Virtually all the testing done in Australia is done with the hardwood test fuel.
A suite of Australian Standards has been prepared over the past 15 years dealing with safe installation of solid-fuel burning appliances, appliance quality, appliance performance (efficiency, heat output rate), and emission of particulates. The safety, performance and emissions standards are widely used by most sectors of the industry and have shaped the on-going development of woodheaters in Australia.
Gilmour and Walker (1995) have criticised the performance and emission standards because they are based on 'correct' heater operation and do not include emissions during the lighting phase of woodheater operation.
The Department of Primary Industries and Energy commissioned the National Fuelwood Study in 1988 (Todd et al. 1989a). The study examined all aspects of residential and industrial fuelwood including historical and projected supply and demand. Information on the species used for residential heating in seven cities (Adelaide, Ballarat, Canberra, Hobart, Melbourne, Perth and Sydney) was collected from fuel merchants, foresters and householders. Fifty-two species were identified. Table 2.4.1 lists the 13 species identified as 'premium' firewood.
The survey also collected information on the quantity of firewood consumed per year in five of the cities through a telephone survey of firewood using households. Table 2.4.2 summarises these results.
The study showed that most firewood was coming from standing or fallen timber associated with land clearing operations. The report concluded that the supply of firewood based on 1988 practices was not sustainable. It recommended better integration of firewood supply and conventional logging to access logging residues, promotion of a wider range of firewood species and planting for firewood supply.
|Common names||Specific names||Where used*|
|Sheoak, Belah, Buloke, Black Oak||Casuarina spp.||H, C, M, B, A|
|Yellow Box||E. melliodora||C, M, B, S|
|Red Box||E. polyanthemos||C, M, B|
|Grey Box||E. microcarpa||C, M|
|Black Box||E. largiflorens||C. M|
|White Box||E. albens||S|
|River Red Gum||E. camaldulensis||C, M, B, A|
|Red Ironbark||E. sideroxylon||M, B, S|
|Mallee Roots||Various||M, B, A, P|
|Black Peppermint||E. amygdalina||H|
|White Peppermint||E. pulchella||H|
|Jarrah||E. marginata||P, A|
Note: * A-Adelaide, B-Ballarat, C-Canberra, H-Hobart, M-Melbourne, P-Perth and S-Sydney
Source: Todd et al. 1989a
|City||Main heating||Secondary heating|
Source: Todd et al. 1989a
In 2000, Driscoll et al. (2000) reviewed the ecological impact of firewood collection in Australia. Their study showed that little had changed since 1988. There was still a strong preference by consumers for dense, slow-growing hardwood species and very little firewood supplied from logging residues. Wood-merchants were travelling long distances to collect firewood because of diminished local supplies. In the ACT, for example, firewood was sourced from up to 450km away.
Driscoll et al. concluded that 72% of commercial firewood is obtained from low rainfall areas including inland and riverine forests, woodland and mallee. These areas are already extensively cleared for agriculture and have relatively slow tree growth rates. Thus, they are most vulnerable to damage from firewood collection. Substantial quantities of firewood are obtained from fallen dead timber and standing dead trees. This dead timber is an important habitat for vertebrates, invertebrates and fungi. Todd and Horwitz (1990) point out that the collection and transport of firewood also spreads insects. Driscoll et al. point out that detailed knowledge of the effects of firewood removal on biodiversity is very limited. They argue that additional information is urgently required.
The question of whether firewood is a renewable source of energy is a vexed one (e.g. does Biomass = stored solar energy? Todd 1991b). The surveys of firewood supply suggest that land clearing has been the major source, but potential clearly exists to provide a sustainable supply. The benefits, due to displacement of fossil fuels, could be substantial. Todd (1990a) argued that an additional 4.6x106t/y of CO2 would be emitted in Australia if fossil fuels replaced the estimated 4.4x106t of residential firewood used per year.
Performance testing of woodheaters for heat output rates and efficiency has been carried out in Australia since 1980. The early work at the University of Tasmania has been summarised in a series of papers (Todd 1981a, Todd 1983c).
A series of research grants from the National Energy Research, Development and Demonstration Program (NERDDC) led to the development of woodheater performance and emission test methods in Australia. In 1985/86, experiments were carried out to compare the various test methods used overseas (e.g. Jaasma and Shelton 1987) and see which proved most suitable for the types of appliances marketed in Australia (Todd and Sawyer 1986). Several stack-loss methods (indirect measurement of efficiency) were compared with the calorimeter room method (direct measure of efficiency). The study concluded that the calorimeter room method would give more accurate measurement of heat output and efficiency. The method involves operating a woodheater within an insulated room with a known airflow through the room and measurements of the temperature of the incoming and outgoing air. By placing the appliance on scales the weight of wood burnt can be monitored.
In 1986, a calorimeter room for accurately measuring the heat output of a woodheater (or any residential heater) was constructed and commissioned (Todd and Sawyer 1987). This research developed the fuelling and operating procedures for the Australian Standard performance and emission tests. Calorimeter rooms based on this design have been constructed at the two laboratories registered by NATA for woodheater testing in Australia: Amdel in South Australia and HRL in Victoria. At least two Australian woodheater manufacturers have also built calorimeter rooms for their own product development.
Performance testing of woodheaters in Australia is required as part of emission testing. Performance testing must be carried out in accordance with the Australian Standard AS4012. Thus, information on efficiency and heat output rates is also available for the 322 heater models that have obtained emission certification (EIC 2000). Figure 2.5.1 shows the range of efficiencies for all certified heater models based on the average efficiency at high medium and low heat output rates. Figure 2.5.2 shows the average heat output rate (power) for the appliances when run on the maximum air setting.
Source: EIC 2000 database
Source: EIC 2000 database
The arithmetic mean of the efficiencies of all heater models is 62.1% and the geometric mean is 62.7%. The arithmetic mean of the high heat outputs is 10.5kW and the geometric mean is 10.4kW. The possibility of setting minimum acceptable efficiency limits for woodheaters has been discussed as a means of reducing wood-smoke emissions. Increasing the average efficiency by five percentage points, for example, would reduce firewood use by eight per cent, assuming the same heat is delivered to households.
This section reviews all woodheater emission measurements published in Australia. It is divided into two sections: the first reviews the large database associated with the woodheater certification program in Australia; the second reviews all the available emission data from other sources. Most of the emission factor data were gathered using the Australian Standard method (see section 2.3.3d), although a number of different methods are available (Quraishi 1986a).
The Energy Information Centre (EIC), Adelaide, holds the most extensive data set of emission values and performance values. The EIC acts as a clearinghouse for testing carried out for the purpose of gaining certification under AS 4013. As discussed in Section 2.3.3, such certification is required for any heater models sold in Australian states and territories where the Standard has been called up in legislation.
The certification test results represent a valuable database of emissions for the range of heaters sold in Australia and for heaters fuelled with eucalypt species of firewood. The spread of emissions factors for certified heaters is shown in Figure 2.6.1.
Source: EIC 2000 database
A total of 322 heater models had been certified as complying with AS4013 in 2000. In some cases more than one model of heater is issued certification on the basis of a single series of tests. This may apply where two or more models have identical firebox and combustion air configurations and the test laboratory is satisfied that changes to the decorative casings would not increase emissions above those of the model tested.
For all models tested, the arithmetic mean emission factor is 3.3g/kg and the geometric mean is also 3.3g/kg. If only those models complying with the 1999 revision of the Standard (i.e. limiting emission factors to a maximum of 4g/kg) are considered the arithmetic mean is 2.8g/kg and the geometric mean is 2.9g/kg.
These emission factors assume the heater is fuelled with air-dry eucalypt fuel and operated correctly. Once an appliance is installed in a person's home there is no control over the quality of firewood used or over operating habits. There have been no in-situ measurements of heater emissions or heater performance in people's homes in Australia. The average figures also assume that the 322 certified heater models are equally represented in the market. No information is available on which models are most popular. Finally, prior to 1992, woodheaters were not tested under standard conditions and very little is known of their performance and emission characteristics. What little testing was done, and published, is reviewed later in this section.
In order to derive average emission factors for Australian heaters, Todd (1997a) estimated the proportion of certified and non-certified woodheaters in use (assumed 15% certified heaters in 1997), estimated what proportion of households used their heaters correctly (assumed 40% correct use), and also assumed about 15% of households were using their heaters very badly. With these assumptions, an average emission factor of 13.6 g/kg was calculated. Todd's analysis shows that by replacing older woodheaters with low emission models, achieving 85% correct operation and only 1% very poor operation, the average emission factor could be reduced to 3.2 g/kg. This analysis was purely theoretical and based on many assumptions for which no sound scientific data is yet available.
Emission tests on woodheaters were conducted at the University of Tasmania between 1984 and 1992. This testing involved trials of various emission measurement techniques, development of the test method adopted as the Australian Standard, and examination of various heater and operator parameters on emissions.
A series of tests were conducted by Quraishi at the University of Tasmania using an Australian manufactured heater that was designed to be used with or without catalysts fitted (Quraishi 1987). The heater was also fitted with an automatic combustion air control with three burn rate settings: high, medium and low. Emission testing for carbon monoxide and particles (using the Condar method, see Section 3.2) were carried out simultaneously. The heater was tested with large (> 9 kg) and small (<9 kg) fuel loads, split eucalypt firewood, firewood brands 1 , and pine brands. Quraishi (1987) concluded:
- on this model of heater the catalyst increased emissions compared to non-catalytic operation (emission factor with catalyst 12.0 g/kg, standard deviation [s.d.] 8.75; without catalyst 6.4 g/kg, s.d. 4.7);
- large fuel loads gave higher emission factors for all fuel types, for split eucalypt firewood the average emission factor for small loads was 4.4 g/kg and for large loads it was 11.5 g/kg;
- average emission factors with eucalypt brands were the lowest (1.81 g/kg, s.d. 1.31), next were pine brands (3.26 g/kg, s.d. 1.63), with split eucalypt firewood having the highest emission factor (8.15 g/kg, s.d. 6.68);
- higher fuel burn rates (>2.5 kg/h) resulted in higher emission factors for pine and eucalypt brands, but lower emission factors for split eucalypt logs; and
- no correlation between CO and particle emissions was observed.
The poor performance of the heater when the catalyst was fitted may have been a function of the heater design and should not be assumed for other catalytic heater models (as discussed in Section 3.1.2).
The results of these tests were reported in a series of papers, reports and a thesis:
Quraishi (1985a); Quraishi (1987), PhD thesis; Quraishi and Todd (1986); Todd and Quraishi (1986a); and Todd and Quraishi (1986b).
In 1987, during the development of an emission tunnel for determining woodheater particulate emissions in some complete tests using dry and wet eucalypt fuel, and brown coal briquettes (Todd et al. 1988). The tests showed high variability in emission results and it was not possible to draw any conclusions regarding relative emissions for the various fuels.
The final research study under the NERDDC funding program was a comparative study of performance and emissions when burning softwood and hardwoods (Todd 1991a). Three commercial models of woodheater were used. One hundred and seventeen burn cycles were monitored.
No statistically significant difference in heater efficiency was observed between hardwood and softwood fuels. This applied to high, medium and low burn rates in all three appliances. The conclusion drawn from these results was that the efficiency of woodheaters was not influenced by wood species.
The emissions from the three heaters are summarized in Table 2.6.1. These results suggest that there is little difference in emission factors when burning the heater at high or medium burn rates. However, at low burn rates the emissions from softwoods are two to three times greater than from hardwoods.
|Heater||Burn rate||Fuel||Emission factor (g/kg)|
|Heater A||High||Eucalypt||1.0 (± 0.6)*|
|High||Pine||0.7 (± 0.3)*|
|Medium||Eucalypt||1.9 (± 0.8)*|
|Medium||Pine||2.1 (± 0.7)*|
|Low||Eucalypt||6.0 (± 2.5)*|
|Low||Pine||18.2 (± 10.9)*|
|Heater B||High||Eucalypt||7.9 (± 3.0)*|
|High||Pine||6.4 (± 3.3)*|
|Medium||Eucalypt||8.5 (± 1.4)*|
|Medium||Pine||9.6 (± 2.4)*|
|Heater C||High||Eucalypt||2.0 (± 1.4)*|
|High||Pine||0.8 (± 0.2)*|
|Low||Eucalypt||25.0 (± 3.3)*|
|Low||Pine||45.2 (± 1.7)*|
Note: * the emission factor is an average of several tests, the number shown in brackets is one standard deviation for the results used to calculate the average.
Source: Todd 1991a
These heaters were pre-1992 models and so had not been tested for compliance with the Australian Standard for emissions. Thus, the eucalypt results provide an indication of emission figures for older models of heater. Heater A had an average emission figure of 3.0 g/kg, which would pass the emission test. Heater B had an average figure of 8.2 g/kg based on just high and medium burn rates. It is likely that the low burn test would have increased this by a factor of 1.5 to 2. This heater would not be certified under the present system. The third heater had an emission factor of 13.5 g/kg from high and low burn test results. This model would also fail the present test requirement. The overall average emission factor for these three heaters is 8.1 g/kg, which is 2.5 times greater than the average emission factor for all heaters now certified (see Section 2.6.1).
The same series of tests included tests with wet (green) pine at high burn rate in one heater model. The results are summarized in Table 2.6.2. The general applicability of the results is limited because only one heater was tested and only at the high burn rate. The results show a 50% increase in emissions for the wet pine. Intuitively, one might expect greater increases in emissions with wet wood at medium and low burn rates, but there is not experimental evidence to back this up.
|16||14.3 (± 0.8)||49 (± 3)||34.2 (± 19.1)||6.4 (± 3.3)|
|40||11.9 (± 0.7)||42 (± 2)||46.9 (± 5.6)||9.2 (± 1.5)|
Note: One standard deviation shown in brackets
Source: Todd 1991a
Emission testing was also conducted on one heater using firewood 'brands' (see above for explanation of 'brands'). The reason for this series of tests was to explore the differences that adopting the US test fuel criteria for emission testing in Australia. The results are summarized in Table 2.6.3. The results show an interesting feature of some woodheaters, that is, much greater emissions when the burn rate of the wood produces more volatiles than the oxygen supply can deal with. The pine brands show a factor of 10 increase in emissions, apparently for this reason. The early stage of the burn cycle is so rapid, because flame can easily penetrate the wood load, that high emissions result.
|Eucalypt brands||13.6 (± 0.7)||47 (± 2.0)||5.2 (± 2.3)||1.0 (± 0.4)|
|Euc. Firewood||13.8 (± 0.7)||51 (± 3.0)||4.9 (± 3.0)||1.0 (± 0.6)|
|Pine brands||14.9 (± 2.4)||53 (± 3.0)||39.6 (± 32.0)||10.6 (± 8.7)|
|Pine firewood||14.3 (± 0.8)||40 (± 4.0)||4.1 (± 1.9)||0.7 (± 0.3)|
Note: Numbers in brackets are one standard deviation.
Source: Todd 1991a
A research program to develop a heater capable of burning brown coal briquettes with good efficiency and low emissions was commissioned in 1988/89 by the Coal Corporation of Victoria and an Australian heater manufacturer (Todd and Wingham 1988, Wingham 1990). A downdraught design was developed, about the same size as a conventional woodheater but including a gravity feed fuel hopper. The results were promising with unattended burn times of 15 hours, efficiency of about 70%, heat outputs adjustable from 3.4 to 16kW and emissions of 3.8g/kg. This emission factor was much lower than any other commercial appliance when fuelled with brown coal briquettes. The appliance was not developed commercially. It was never tested with firewood. The design might have further promise because, as discussed in Section 3.1.2, downdraught combustion systems, where the smoke is drawn downwards through the hot coal bed, offer potential for very low emissions.
Chesterman (1984) collected particulate and gaseous samples of emissions from a woodheater, fuelled with eucalypt firewood, operating at the University of Tasmania and carried out chemical analysis using gas chromatograph and gas chromatograph/mass spectrometry methods. He identified 55 organic compounds but was unable to quantify the emissions. The compounds identified were similar to those identified in US tests (see Section 3 2). Quraishi et al. (1984) report similar measurements identifying biphenyl, methyl anthracene, phenanthrene, anthracene, propyl fluorene, fluoranthene and pyrene.
Freeman and Cattell (1990) measured polycyclic aromatic hydrocarbons (PAH) from open fireplaces burning eucalypt firewood as part of a larger study of PAH in Sydney. Eleven PAH species were measured from sources such as open fireplaces, bush fires, back-yard burning, cigarettes and a commercial incinerator. Emission factors were not measured. Results were expressed in terms of species concentration in particulate matter in the smoke. They concluded that the mix of PAH species was similar from all these sources except that bush fires showed relatively higher concentrations of benzo(a)pyrene and coronene.
No measurements of dioxin emissions from woodheaters or open fireplaces have been made in Australia. The current CSIRO study will rectify this gap in local data.
However, in assessments of dioxin sources in Australia, residential use of firewood has been included (Pacific Air & Environment 1998). The emission factors used were based on UK data. The study concludes that residential firewood use is the fourth largest category of dioxin emissions: behind prescribed burning, bush fires and cement production, but ahead of coal combustion. The assumed emission factors for 'clean' firewood are 1 to 3 µg/tonne for woodheaters and 1 to 29 µg/tonne for open fireplaces. The study also assumes emission factors of 5 to 50 µg/tonne and 100 to 500 µg/tonne for 'treated' wood burnt in woodheaters and open fireplaces respectively. In view of the very limited scientific data on dioxin emissions from residential firewood use, these assumptions are probably the best available. However, in applying these to Australian firewood use, Pacific Air & Environment have assumed that 470 000 tonnes of 'treated' wood is burnt annually. There is no evidence that this is the case; in fact all firewood surveys in Australia indicate very little waste wood or treated wood is consumed. If it is assumed that all treated wood is replaced with clean firewood then residential firewood use drops to the seventh or eighth most significant source of dioxins in Australia.
Studies of ambient air quality, particularly those examining PM10 and haze, were slow to pick up the influence of wood-smoke from residential heating. In Perth WA for example, commentators through to the mid-1980s focussed their attention on transport and industry sources (Robertson et al. 1985, 1986), even though, with the wisdom of hindsight, it is likely that wood-smoke was significant by that time. Similarly, a study of ambient PAH concentrations in Sydney, Port Kembla and Newcastle in 1984/5 (Pradhan 1986) attributed much higher winter concentrations in suburban areas to an increase in fossil fuels used for residential heating rather than firewood use. One exception to this was the study by Taylor et al. (1987) that used radiocarbon dating to establish the significant contribution to winter PM10 from woodheaters in Canberra.
Emission inventory studies (e.g. Boyle et al. 1996) acted as a catalyst for government action on wood-smoke in Australia because they demonstrated that firewood use was contributing a high proportion of PM10 in winter months in many major urban areas in Australia. Some initial calculation errors made the situation appear worse than it probably was, but even without these errors wood-smoke was clearly a significant air pollutant.
Launceston, a city of about 100 000 inhabitants in the Tamar Valley in northern Tasmania, has developed a reputation as one of the cities most affected by wood-smoke in Australia. The city is subject to winter inversions that reduce dispersion of air pollutants. Firewood is the preferred heating fuel for more than half the households in the air shed. Winter fogs exacerbate the perceived problem of wood-smoke, creating extended periods of poor visibility and obvious wood-smoke odour. The local community seemed to accept these conditions for many years, seeing them as more of a nuisance than a health risk. This was despite early warnings of potential wood-smoke problems in Tasmania (Todd 1981d). In 1990, Dr Lloyd Lyons, Northern Region Health Board called together a Working Party of air pollution and health experts to examine the problem of wood-smoke in more detail. Preliminary measurements of PM10 and TSP in the winter of 1991 suggested particulate concentrations exceeded 200 mg/m³ on several occasions. At the time, the suggested goal for PM10 was 120 mg/m³ (Streeton 1990), but observed concentrations were high enough to encourage the Working Party to mount a larger study, which continued for two more years. It was during this period that epidemiological studies (see Section 3.5.1) indicated much lower concentrations of PM10 were required if health impacts were to be avoided.
The Working Party's report (Lyons 1996) summarises the results of PM10 measurements at four sites and TSP measurements at one site. The Working Party reports that particulate levels exceeded 120 µg/m³ (24 hour average) on 15 days in 1992 and 3 days in 1993. Examination of the graphical information in the report suggests that about 50% of the winter days exceeded 50 µg/m³ in 1992 and 1993. Particles were analysed for a number of PAHs but only the benzo(a)pyrene results were reported. Table 2.7.1 summarises these results.
|Location||Jul – Sep 1991||May – Dec 1992||Jan – Sep 1993|
Source: Lyons 1996
Interestingly, the Working Party reported a strong correlation between PM10 and lead at all sites (r = 0.9). Since lead is normally associated with automotive or industrial sources, this raised some doubts about the assumption that wood-smoke was the main cause of winter particulates. The Working Party did not address this issue.
The Working Party recommended urgent action to control sources of PM10 in the air shed and continuation of the monitoring program.
The Department of Environment and Land Management (now Department of Primary Industries, Water and Environment), in fact, continued monitoring in Launceston. Carnovale (1997) reports on measurements from1991 to 1996. Updates of the on-going measurement program were released in 1998 and 2000. Table 2.7.2 summarises annual average values for PM10.
The data presented in Table 2.7.2 shows significant variation in annual average PM10 concentrations at the Ti Tree site. It is difficult to identify any clear tends. However, the number of days per year that exceeded 50 µg/m³ appears to have declined: 47 in 1997, 45 in 1998, 38 in 1999, and 36 in 2000. Whether or not any trend is apparent, a substantial improvement is necessary to achieve the Air NEPM goal of not more than five exceedences per year.
Analysis of the size distribution of particles in Launceston's air (Keywood et al. 2000) identified a strong peak below 1mm, which was attributed to wood-smoke through matching with non-sea salt potassium (used as an indicator of biomass source).
Ainsworth (1996) reports on PM10 measurements in Armidale, a rural NSW city with a high proportion of firewood-using households and winter PM10 problems. Limited measurements in July and August 1995 showed two of the six 24-hour periods measured using a High Volume Sampler exceeded 50 µg/m³ PM10 with an average value over 12 days of 20 µg/m³. Light scattering measurements, obtained using a nephelometer, showed very high concentrations of scattering particles during the late evening and early morning with one 3-hour High Volume sample showing 172 µg/m³ PM10 between 10pm and 1am. The concerns about wood-smoke in Armidale have been summarised in a monograph edited by Parton (1998).
|Year||East Launceston||Glen Dhu||Newstead||Newnham||Ti Tree|
Note: * in 1992 and 1993 TSP was measured at the Ti Tree site.
Source: Carnovale 1997 and updates
Berko (1999) has prepared the 'State of Knowledge Report on PAHs in Australia' for Environment Australia. The study noted that there had been eight main studies of ambient air PAHs in Australian cities since 1990. The studies showed PAH concentrations in winter were 2 to 5 times greater than in summer. Most studies attributed the PAH emissions to domestic heating or other combustion of organic matter during the winter. Table 2.7.3 summarises the maximum PAH concentrations measured in the eight studies. Comparison with Dutch National Institute for Public Health and the Environment Maximum Permissible Concentrations (a risk based limit) suggest that average concentrations of benzo(a)pyrene in most Australian cities are below the recommended value of 1 ng/m³ however Perth, Western Australia and Launceston, Tasmania had average values exceeding this recommended value, with average values of 1.88 and 1.77 ng/m³ respectively. The 1 ng/m³ goal is lower than the proposed German Federal Environment Agency goal of 10 ng/m³ and the Dutch interim goal of 5 ng/m³. So, by either of these criteria, the current Australian studies do not identify any excessive levels.
Gras (1996) in the Perth, WA haze study observed all the chemical species listed in Table 2.7.2 plus 2-methyl naphthalene, acenaphthene, acenaphthylene, anthracene, fluorene, indeno(1,2,3-c,d)pyrene, naphthalene, perylene and vanillan.
|Compound||Maximum concentration (ng/m³)||Sample period|
Source: Berko 1999
Atmospheric particle size distributions have been carried out by CSIRO in six Australian cities (Ayers et al. 1999). This pilot study provided details of a wide variety of chemical and physical properties of particles. A detailed discussion of these measurements for Launceston during the winter months when wood-smoke dominates the fine particle mass is presented in Keywood et al. (2000) and Gras et al. (2000). This study demonstrated the role of wood-smoke in particle size distribution with a mass peak between 0.6 and 1µ m diameter. The study also showed a strong correlation between PM2.5 and scattering coefficients.
Gras (1996) studied the particle size distribution associated with haze in Perth, WA over 1.4 years (two winters). Winter measurements, under poor visibility conditions showed high levels of 'modern' carbon suggesting biomass combustion as the source (i.e. residential wood burning).
There have been no studies of the direct impact of wood-smoke on human health in Australia. However, there have been epidemiological studies establishing correlations between human health and PM10. There have also been useful reviews by Australian researchers of international literature on the possible impacts of wood-smoke and PM10 on human health (Gras 1996, Robinson and Campbell 1998). However, the significance of wood-smoke as a component of ambient air pollutants was only acknowledged quite late in Australia, significantly later than in the United States for example (see Section 3.2). As late as 1991, an Australian review of air pollutants and respiratory disease (Abramson and Voigt 1991) did not mention residential firewood use as a source of pollutants.
Morgan et al. (1998a) report on correlation between daily mortality and light scattering coefficient (derived by nephelometer and a surrogate for particulate mass) in Sydney from 1989 to 1993. They found an increase in all-cause mortality of 2.6% associated with an increase in mean particulate concentrations from the 10th to the 90th percentile (10 to 56 inverse megametre in the units of the scattering coefficient). Baruch (1998) notes that these results are consistent with international studies (see Section 3.5). Table 2.8.1 summarises this comparison. Lewis (1998) reports on an observed link between PM10 and chest colds and nighttime cough in the Hunter-Illawarra region of NSW.
|Indicator||International Literature||NSW Study|
Morgan et al. (1998b) have also examined the link between air pollution and hospital admissions for Sydney. They found a statistically significant link between chronic obstructive pulmonary disease (COPD) in the elderly (over 65 years) and particulates (as measured by nephelometer) with a 3% increase when the one-hour particulate concentration increased from the 10th to the 90th percentile (23 to 142 inverse megametre). Correlations with asthma and heart disease were not found to be significant.
The Melbourne Mortality Study (EPA Vic 2000d) examined links between air pollution and mortality between1991 and 1996. The study (based on light scattering coefficient determined using nephelometers) suggested a 1.4% increase in mortality for a 10 µ g/m³ increase in PM2.5. The study found significant correlations in summer months but not in winter months. The report noted the difficulty in controlling for confounding factors.
Simpson et al. (1997) report similar links between mortality and particulate material (measured using nephelometer-derived scattering coefficient data) for Brisbane. Their results suggest an increase in mortality of 0.9 to 1.8% for each µ g/m³ increase in PM10 (the range is a function of the conversion factor used to convert from scattering coefficient to PM10). The effect was greatest in summer months and for people over 65 years.
The stronger association between particulates in summer months compared to winter months suggests that sources other than woodheaters are significant, although it does not eliminate woodheaters as a potential problem.
A study of preschool children in South Australia found a significant reduction in the prevalence of dry cough and wheeze in households with woodheaters compared to other forms of heating (Volkmer et al. 1995). The study identified increased dry cough and wheeze in households with unflued gas heaters.
A potential problem, little addressed in the scientific or health literature, is the accumulation of creosote in tank water for households using roof-collected rain water (Todd 1989). Many rural households use firewood for heating, water heating and cooking, this creates a potential problem of wood-smoke fallout (creosote) collecting on roofs and washing into water tanks.
Community education is an important control measure for reducing emissions of wood-smoke. It is known that very poor operation of a woodheater can increase emissions by a factor of 10 or more (e.g. Todd 1997b). Careless operation, i.e. failure to operate the heater according to instructions, typically doubles the emissions (Todd 1996c). If it is assumed that many people do not take particular care when operating their woodheaters, then any program that achieved careful operation by the majority of woodheater users could significantly reduce wood-smoke problems.
The importance of correct use of woodheaters has been stressed in Australia since 1983 (Todd 1983d) and repeated in many forums since then. Through the 1980s, the main medium for educating the public was the provision of pamphlets. Most states had various pamphlets about woodheaters and firewood available from Energy Information Centres, Environment Departments and woodheater retail outlets. Table 2.9.1 provides information on a selection of these brochures.
The information provided in the brochures reflected the current state of knowledge about optimum woodheater operation at the time. Table 2.9.2 provides an example of the sorts of suggestions included in many of the brochures.
The benefits of providing this advice have not been measured. It has been assumed that some heater users have accepted the advice and so benefits have occurred. However, as demonstrated in papers reviewed in Section 2.7, air quality continued to be adversely affected by firewood combustion, suggesting education campaigns have not achieved their goals.
|Victorian Solar Energy Council – a set of seven brochures (1986)|
|Types of wood heaters
Buying a wood heater
Installation checklist for wood heaters
Operating hints for wood heaters
Wood heating glossary
|Mines and Energy, and Environment and Planning South Australia (1986)|
|Light your fire – how to operate a solid fuel heater successfully|
|Forestry Commission Tasmania (1985)|
Cutting Firewood safely
|Environment Protection Authority, NSW (1987)|
|Is your wood going up in smoke?
Let's clear the air
|Solid Fuel and Wood Heating Association (various dates)|
|Your burning questions answered
Getting the most from your wood heater
Wood – nature's housewarming gift. Use it wisely
|Department of Territories, Canberra (1986)|
|Let's talk fireplaces|
|Municipality of Kingborough, Tasmania (c1986)|
|Stop the home fires smoking|
A more structured approach to education of woodheater users was attempted in Launceston, Tasmania in 1991 (Todd 1992) working with school science teachers, community groups, providing articles to community and regional newspapers, and participating in radio talkback programs. Participating primary and secondary school teachers enthusiastically supported the education program. In regions with a high proportion of wood-heated homes, i.e. where discussing woodheaters is relevant to many in a class, school programs appear effective in disseminating advice on correct heater use. The Launceston program was unfunded, and so only ran for one heating season. The outcomes were not quantified.
The Airwatch program, a national project introducing school children to air pollution issues, (Manins et al. 1995) might play a role in disseminating information and teaching packages on wood-smoke minimization actions to schools.
Articles on correct heater use and maintenance in magazines can also inform householders on wood-smoke minimization practices, e.g. Owner Builder (Todd 1982, Todd 1983d), Today (Todd 1991c) and Earth Garden (Todd 1996b). Some articles targeting, for example, teachers were also prepared (Todd 1981e).
Source: Todd 1997b
A more systematic study of the role of community education in reducing wood-smoke was carried out by McDonnell (1998). McDonnell worked with existing community groups, encouraging them to disseminate information on correct heater use to their members and the neighbourhoods in which they were active. This led to a multiplier factor of over 200, with direct contact with about 100 people achieving information dissemination to over 21 000 households (McDonnell and Todd 1997).
Ainsworth and Gow (1998) suggested a range of actions that local government might take to reduce wood-smoke including: interest free loans for households wanting to replace old woodheaters; licensing woodfuel suppliers; energy efficiency requirements for new homes; and notices to force upgrading of old appliances (although this was not a favoured activity). The suggestion that woodheaters should be banned was rejected because of the impact on low-income households.
In 1997 the Commonwealth government, in cooperation with the Tasmanian and Western Australian governments, ran a television and radio campaign 'Breathe the Benefits', supported with newspaper articles, pamphlets and 'fridge' magnets, aimed at putting across five simple points on correct woodheater operation (Schweizer 1997). The five points were:
- burn only dry wood;
- keep wood stored under cover;
- use small logs;
- burn the fire brightly; and
- do not let the heater smoulder overnight.
The media campaign continued for two years. It was supported by an Internet site, which provides more detailed advice on correct heater operation (Environment Australia 2000).
The 'Breathe the Benefits' campaign was backed up with pre- and post-campaign surveys in 1997 in Tasmania and Western Australia to assess the effectiveness of the coverage (Attwater and Thorpe 1997a, 1997b, 1997c, 1997d). In Tasmania there was a high awareness of the campaign (72%) with measurable effect on attitudes and practices. There was high level of recall of the campaign messages. In Perth, WA the awareness of the campaign was lower (47%) with television advertisements being recalled by about one third of those surveyed and newspapers and radio recalled by about one quarter.
The advertising campaign was extended to six states, focussing on regions known to suffer from wood-smoke problems. Further surveys to assess the impact of the campaign in 1999 (the last year of the radio and television 'Breathe the Benefits' advertisements) indicated good recall in those areas where other, local education campaigns were running concurrently (Attwater et al. 1999). In these areas, recall of the campaign was about 50%; in other areas the recall rate was about 35% for woodheater owners and 18% for others.
The Australian Wood Heating Association (now Australian Home Heating Association) believes that effective education campaigns can reduce the wood-smoke problem to acceptable levels (Mogg 1997). The Association provides pamphlets with practical advice on smoke reduction. It also provides a service to local government, where Association members will speak with woodheater users where a smoke nuisance has been reported and demonstrate to offending heater users how their heater can be operated with minimum smoke (AWHA 1997, p 13).
While community education campaigns have had undoubted benefits on some woodheater users' behaviour, there is cause for scepticism about their overall effectiveness. Some critics argue that the message has been too 'soft' and that brochures and electronic media advertising should stress the potential health impacts of wood-smoke (Robinson et al. 1998a). Recently several commentators have argued that education campaigns should target households where excessive smoke is observed (i.e. through smoke patrols, smoke inspectors, smoke police or similar terminology) (e.g. Todd et al. 1997, AWHA 1997, Robinson et al. 1998b).
The review of Australian literature on firewood use, ambient wood-smoke concentrations, and wood-smoke emission factors shows:
- about 1.5 million Australian households use firewood;
- the residential sector burns about 4 million tonnes of firewood per year;
- firewood use appears to have peaked in about 1992 and is slowly decreasing, but only by around 10 000 tonnes per year;
- firewood supply is based mainly on clearing of private land; it is not sustainable and is likely to be causing some ecological damage; better integration with conventional forestry and firewood plantations are required;
- the current generation of woodheaters must be certified to meet the emission factor limit of 4 g/kg when tested in accordance with AS/NZS4013;
- even with certified woodheaters, incorrect heater operation can lead to high emissions, education campaigns to inform households of correct operation do not appear to have been very successful;
- wood-smoke is contributing to decreased air quality in many urban centres and country towns; in some cities, such as Launceston, Tasmania and Armidale, NSW, wood-smoke is considered the main reason particulate goals (50 µg/m³ of PM10) are not being achieved in winter months;
- all Australian states and territories have introduced legislation, or have legislation planned, to address urban wood-smoke problems;
- chemical testing of ambient air with high levels of wood-smoke has identified a range of air toxic compounds similar to those associated with wood-smoke emissions in overseas research; and
- the current emission testing research will better define the toxic compounds associated with wood-smoke in Australia.
1 Firewood brands are sawn pieces of timber with wooden spacers nailed to them to maintain fixed spacing (vertical and horizontal) in the combustion chamber. They are used as the standard fuel in US emission testing (Douglas fir) but not in Australian standard emission testing. The spacers allow much greater penetration of combustion air between the pieces of firewood. The brands do not simulate real-world firewood loads.