The role of bioethanol flueless fireplaces on indoor air quality: Focus on odour emissions

This study concerns flueless fireplaces powered by liquid or gel bioethanol based fuels. These devices have a pleasant aesthetic design and can be used in indoor environments; in particular, they do not need any connection to a stack to evacuate the flue gases. This work evaluates the polluting impact of the mentioned fireplaces, with a special focus on their odour emissions, in order to assess the environmental impact of these items and to provide the European Commission information useful to define the guidelines for a dedicated legislation. For these reasons, a series of experimental tests, structured with well-defined steps, alternating operation (combustion) and shutdown phases, was performed for several fireplaces. The concentration trends of both the main combustion products and by-products as well as the odour were monitored; furthermore, specific odour emission factors (OEFs) were calculated. The combustion pollutants were mainly released during the operation phase, while the most significant odour emissions occurred during shutdown. The average OEFs reached values between 40 and 110 [*100 ouE kJ −1 ] during the shutdown, but they were below 10 [*100 ouE kJ −1 ] during the operation periods. It was found that the extent of odour emissions depends crucially on the burner design and geometry of each fireplace; in particular, the air-fuel contact surface is the most relevant parameter. Moreover, this study proved that the electronic nose can be a valid additional instrument in activities aimed at evaluating the indoor air quality, and considering its peculiarities, the idea of using it not only as an odour detector, but also as an integrated device in air ventilation systems for indoor environments, is both interesting and achievable.