One of the postings re car park ventilation noise mention that the fans start when a car enters the car park. AS1668.2 provides for simple systems for car parks accommodating less than 50 vehicles, This prescriptive design is sloppy and cheap only requiring a photo – electric beam at the car park entry and a “guess as to how long the fans should operate – a cost of probably less than $1,000.
The best compliant performance design is to use Carbon Monoxide monitoring which activates when levels reach certain levels and shuts down when the levels drop. With this system occupants should be educated as not to leave engines running in the car park – this will cause the fans to run all the time!
I hope that this comment is useful.
Retired Mechanical and Fire Safety Engineer