Problems in residential design for ventilation and noise part 2: Mechanical ventilation

Part 1 of this article described the design drivers and regulatory regime for noise and ventilation in dwellings through the Planning system and Building Regulations. This part discusses noise aspects of mechanical ventilation systems in dwellings. Mechanical ventilation is increasingly adopted to meet more onerous energy performance requirements, or to limit the potential for external noise ingress. General limits for internal ambient noise levels described in the World Health Organisations Guidelines for Community Noise (GCN)[1] are generally unsuitable for noise from mechanical services, as they are frequently too high to tolerate. Noise from mechanical ventilation systems is not currently regulated in the UK. In the UK the industry for the design, supply, installation, commissioning and maintenance of domestic mechanical ventilation systems is currently in its infancy. Although the skills and expertise required to address all issues in every part of the supply chain are present and utilised for commercial buildings, they are rarely applied to dwellings. Failures in parts of the supply chain can result in excessive noise levels. Domestic mechanical ventilation systems have at times attracted bad press as if they are the cause of problems in buildings, when it has often been failures in the design, installation and commissioning that makes them unsuitable to use. With an industry currently unwilling to acknowledge the challenges of providing appropriate mechanical ventilation systems in dwellings and in the absence of regulation of noise levels, it is unsurprising that excessive noise frequently results. As the systems are usually under the control of the occupants, systems are generally operated at the level at which noise is tolerable – or turned off completely. As noted in part one of this article, the adverse impact of inadequate ventilation upon health and well-being is extensively documented as a public health problem and is not repeated here. The ventilation requirements and conditions under Part F are described first. This article is based on the paper presented at the 2013 IOA Spring conference, with additional material that has subsequently become available.