VOICES | JACK HARVIE-CLARK Loud and clear Excessive noise from mechanical ventilation systems can have a detrimental effect on the comfort of building occupants, but Apex Acoustics Jack Harvie-Clark believes the proposed Approved Document F fails to address the issue A s part of the governments consultation on the Future Homes Standard, Approved Document F (AD F) is also out for consultation.1 This is a great opportunity for the government to go beyond the current position, in paragraph 4.34 of AD F 2010, that noise caused by ventilation systems is not controlled under the Building Regulations. Most people have personal experience of annoying noise from mechanical ventilation systems, which causes them to turn it down or off. In older, less airtight houses, there is likely to be sufficient ventilation from infiltration to avoid really poor indoor air quality. In modern, airtight houses, however, occupants rely on the effective operation of their ventilation systems to enable good indoor air quality. The research for our 2019 article, How loud is too loud: noise from domestic mechanical ventilation systems,2 in the International Journal of Ventilation, was issued with the consultation,3 and reinforces the risks that excessive noise causes for occupants. So how does the consultation draft AD F help prevent this unintended adverse consequence? (See panel AD F consultation draft wording). For one thing, it omits the line that indicates noise is not controlled under the Building Regulations but how does it propose to control noise in the future? Bizarre issues JACK HARVIE-CLARK is founder of Apex Acoustics The current proposal in the draft AD F (see panel) is entirely inadequate to address noise from mechanical systems. There are no objective standards to meet and, rather bizarrely, the issues highlighted in paragraph 1.5 dont mention noise from the fan. Why use terms such as minimise noise and not unduly noisy, rather than state objective noise levels that we can measure? Also surprisingly, reference is made to taking account of outside noise when considering the suitability of opening windows for purge ventilation. Is this purge ventilation, as described in AD F, to rapidly dilute pollutants and/or water vapour? From an acoustic perspective, there would be few concerns about external noise ingress when using it in this way. The more common use of purge ventilation is to mitigate overheating, but that is a separate issue. Why does this draft talk about sizing and jointing ducts correctly, rather than simply stating noise criteria to be achieved? If noise is controlled under the Building Regulations, contractors will quickly find out how to make sure their designs and installations work. The Building Control body can check or ask for thirdparty verification; measurements of noise levels can easily be made if there is any doubt about whether they comply with the criteria. Need for regulation The necessity to include noise from ventilation systems within the Building Regulations is evident to stop occupants suffering poor indoor environmental quality (IEQ) as a result of intolerable noise. There needs to be: Performance standards for sound from ventilation systems Demonstration of compliance at the design stage Demonstration of compliance on completion. We suggest the minimum performance standard to prevent most people being annoyed is: Whole dwelling ventilation: sound from any type of mechanical ventilation system when measured according to BS EN ISO 16032 should not exceed: 26 dB LAeq, T in bedrooms, and 30 dB LAeq, T living rooms. Extract ventilation: sound from any type of mechanical ventilation system when measured according to BS EN ISO 16032 should not exceed: 26 dB LAeq, T in bedrooms, and 35 dB LAeq, T in living rooms, and 45 dB LAeq, T in kitchens, sanitary accommodation and bathrooms. The requirement relating to whole-dwelling ventilation should include sound from mechanical extract ventilation (MEV) and mechanical ventilation with heat recovery (MVHR) systems. The one relating to extract ventilation It would be useful to have a consistent approach to describing sound levels, so designers can compare products and building control bodies can determine compliance 20 January 2020 www.cibsejournal.com CIBSE Jan20 pp20-21 Jack Harvie Clark.indd 20 20/12/2019 17:02