Noise from Essential Services car park fans

I thought I’d post a follow up.

The OC Committee commissioned an Acoustic Engineer to investigate the noise issue. The Acoustic Engineer deemed the noise to be “illegal” and that “an authority (e.g. health officer from the council) could order the OC to rectify the noise problem under the health act or noise regulations”.  The engineer recommended a change to a Carbon Monoxide Monitoring System (CMMS). All other advice to the Committee suggested that in a low use small residential car park (eg 14 spaces), the likelihood of ventilation fans being needed for a single car arrival or departure would be low.  When used with a Variable Speed Drive, even if the fans were needed, they could be slow started and initially run at lower (meaning quieter) speeds.

The change to a CMMS needed a building permit process.  That alone would normally mean a special resolution of the OC.   And as only one resident would benefit, the Committee thought that a special resolution would most likely fail.  But because the noise was deemed illegal, the Committee was advised that a special resolution of the OC in this case would not be required – OC’s must operate within the law.  So the Committee alone decided to install the CMMS at OC expense.

The cost was not quite as expensive as we thought: approximately $7,000 with around $2,000 of that being for all the process paperwork required.

The CMMS has solved the noise issue.  The fans rarely operate now and even when they do, they are initially slow started (over 20 seconds) to 40% speed. They are very much quieter at this speed.  But if needed they can still be operated at full speed.

It was interesting to see what the actual CO PPM (Carbon Monoxide Parts Per Million) levels in the car park were.  First, here’s what AS 1668.2 states:

Exposure Limit
AS1668.2 allows for:
Any arrangement that is demonstrated to limit the CO concentration, between 900 mm and 2500 mm above the floor, everywhere to –
(i) 60 ppm 1 h maximum average;
(ii) 100 ppm peak value; and
(iii) 30 ppm (Time Weighted Average) 8 h.

With no car activity the controller reads 0 PPM . An arriving car (warm engine) often doesn’t  increase the CO level at all.  Not even by 1 PPM.  But a departing car (cold engine) can cause a ‘cloud’ of CO which can sometimes exceed 30 PPM but quickly drops (in 25 seconds or so) to a steady 4 to 5 PPM once the ‘cloud’ disperses.  If there’s no further car activity, the CO level slowly returns to 0 PPM over the next hour or two.

The CMMS uses less electricity (due to less fan operation) but that saving is offset by increased maintenance costs (the CO sensor needs periodic calibration checks).

The bottom line: We have two very happy residents.