Reducing ventilation noise levels from MVHR systems in housing – Challenges and feasibility of field tests

In Denmark - and probably most countries in Europe - regulatory noise limits apply for noise from ventilation systems in housing. During the last few decades, mechanical ventilation with heat recovery (MVHR) has become increasingly prevalent in new and retrofitted housing in Europe, and such systems may operate continuously 24 hours/day and transmit noise into and between rooms. In practice, many people get annoyed or disturbed by the noise during night or when having quiet activities. Many people complain about the noise, and some people change the operation of the MVHR system or even destroy the system. For new-build and new systems in renovated housing, the ventilation system must comply with a noise limit, LAeq ≤ 30 dB in dwellings, measured and documented using a simplified version of ISO 10052. Due to dissatisfaction from occupants, it is considered reducing the limit to LAeq ≤ 25 dB in living and sleeping rooms, which is currently tested in a voluntary sustainability class (in Danish abbreviated FBK), including use of ISO 16032 for correction of background noise. This paper describes results from a case study comparing the methods and other challenges, when measuring low ventilation noise levels, aiming at providing input for a revised field test method to be applied in the Danish regulations.