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Mechanical Ventilation Rate of Commercial Buildings Index of indicators

Indicator description

Data

Related Indicators

Acknowledgment

Indicator description

This indicator examines the provision of adequate ventilation for indoor air quality. It provides a measure of the fresh air intake rate of commercial buildings relative to requirements of the Building Code of Australia (1990). The Building Code of Australia and state building regulations require that all occupied rooms have 'adequate flow-through or cross-ventilation and air quality', consistent with their function or use. Commercial buildings are to be provided with permanent openable windows or mechanical ventilation systems that meet Australian standards. Mechanical ventilation rates are required to comply with AS 1668.2 and AS 3666. Adherence to these standards ensure removal of objectionable odours, remove the accumulation of harmful contamination by micro-organisms, pathogens and toxins, and provide fresh outdoor air to building occupants.

ASHRAE standard 62 (1989) ventilation requirements

Occupied space

Outdoor air ventilation rate
(L/sec/person)

Bars

15.0

Classrooms

7.5

Conference rooms

10.0

Offices

10.0

Residences

0.35

Theatres

7.5

Dining areas

10.0

Source: ASHRAE 1989


A difficulty arises with mechanical ventilation rates because there is no post-construction monitoring system in place to ensure continued compliance with the relevant Australian standards. The building control system in Australia is one of individual state and territory authorities administering a set of generally uniform technical provisions through individual State administrative acts. The Australian Building Codes Board's role therefore, is merely advisory, so enforcement is generally at local government level.

Future assessments for this indicator could include factors such as thermal comfort criteria, optimal humidity range and concentration of carbon dioxide in steady state conditions.

Data

No systematic evaluation of ventilation rates has occurred in Australia. Limited measurements indicate that a large proportion of commercial buildings in Australia do not comply with AS 1668.2 - 1991. One study (Williams 1992), showed that 82% of 228 low rise office buildings in suburban Melbourne failed to meet Australian standards.

This is in contrast to a Tasmanian study into commercial buildings (Mesaros 1995), which demonstrated that Hobart low rise office buildings were consistent in complying with recommended ventilation rates. Air exchange rates in 61 public and private sector buildings were monitored in the Hobart CBD, Glenorchy and Clarence. Results revealed that the majority of surveyed buildings complied with the ASHRAE standard 62 (of 10L/sec/person). Although, it should be noted that the study was not a long-term investigation, therefore the findings are only representative of a short sampling period.

Buildings in Hobart that did not comply with relevant ventilation standards had consistently more problems regarding microbial contamination such as fungal growth (Mesaros 1995). This is apparent in the photo below, which illustrates the state of some Tasmanian offices.

Acoustic tiles affected by a combination of inadequate ventilation, water damage and fungal growth.

Related Indicators

Thermal Comfort In Commercial Buildings

Air Infiltration Rates of New Housing

Proportion of Commercial and Recreational Buildings with Smoking Prohibition

Acknowledgment

National Human Settlements Key Indicator 7.2 (Newton et. al. 1998).

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Last Modified: 14 Dec 2006
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