Developing the Tasmania protocol to define Ultra-low emission burners for hardwood fuel

In Australia and New Zealand (NZ) domestic wood heater emissions contribute to a substantial community burden of air pollution-related illness and death. Despite increasingly stringent emission standards for wood heaters in Australia, there has been frustratingly little progress in reducing ambient air pollution from this source.  In contrast, Environment Canterbury NZ, has made impressive progress driving innovation in wood heater designs  to improve air quality. Interventions have included the 2014 introduction of a new performance testing standard, the Canterbury Method One (CM1) that is used to define a class of Ultra Low Emission Burners (ULEBs). CM1 testing is conducted under conditions intended to simulate typical home usage and includes the heater’s start-up phase which generates a significant portion of pollutant emissions. It is primarily designed to test the performance of appliances burning softwoods, the main source of fuel in NZ.  We aimed to: (1) design testing protocols based on the CM1 for appliances burning Australian hardwoods, and (2) conduct preliminary evaluations of existing ULEBs fuelled with hardwoods as a test-of-concept for ULEBs in Australia.  The main variation from the CM1 was the use of a single burn phase with double the weight of wood. We also evaluated two different protocols for the start-up phase. We evaluated four certified ULEBs of different designs using our protocol. Emissions from hardwood fuels were higher than for softwoods as anticipated because the appliances we tested had been optimised for softwood combustion. The overall performance of the heaters was promising, although there was large variation between appliances. Our results provide proof-of-concept that ULEBs could potentially be optimised for hardwoods and have a place among strategies for reducing the harm from air pollution in Australia.