Experimental Acoustic Testing Of Alternative Ventilation Ducts.

Ducts of alternative materials to galvanised steel, are widely employed in residential buildings' mechanical ventilation systems in a bid to comply with the conservation of energy regulations in circumstances that prevent the use of natural ventilation. The noise transfer predictions of systems with alternative ducts are still being based on data for galvanised steel due to the lack of acoustic performance data of alternative ventilation ducts tested in controlled conditions. To close this knowledge gap, a test rig was designed and built based on the test set up defined in ISO 7235. Alternative ventilation ducts and associated 90º bend samples were acoustically tested in controlled laboratory conditions utilising customized test rig developed to suit typically small duct profiles of alternative ventilation ducts. Test samples were tested using two methods: the substitution principle as outlined in BS EN ISO 7235 (2009) as well as applying a novel "zero substitution" conceptual approach. The preliminary results of the "zero substitution" approach tests show indication of its validity. [ABSTRACT FROM AUTHOR]