The Advanced Ventilation Technologies Group at CSIRO has extended its expertise to car park ventilation for large shopping centres and ventilation in process buildings in the mining industry.
Car park ventilation design has generally been based on the prescriptive method of AS1688.2-1991 and AS1668.2-2002. While the AS method covers totally enclosed (below street level) car parks fully, it does not adequately cover semi-enclosed above-ground car parks with partial wall openings. In particular, in the estimation of natural ventilation flow rates for car parks, there is no definitive methodolgy to account for airflow through various openings in the building envelope.
A hybrid ventilation (mechanical and natural ventilation) model has been developed by CSIRO to determine the natural ventilation airflow rates for semi-enclosed caer parks. Anecdotal evidence has shown that the prescriptive method often leads to over-design. A performance-based approach, however, can be modelled to parameters specific to the particular car park.
A CSIRO performance-based dilution model on the total carbon monoxide (CO) emission within a car park was developed to compute the total car park ventilation requirement to fulfil Worksafe Australia criteria fore maximum CO exposure during a specified period. It has been shown by post-construction on site CO measurements that a performance-based approach rather than the prescriptive method was more realistic in the determination of car park ventilation air quantity.
For multi-level car parks such as those in large shopping centres, energy consumption due to ventilation requirements can be very high; the CSIRO performance-based design approach will contribute substantially to the reduction of building energy usage. In some semi-open car parks, application of the model may mean the difference between requiring supplementary mechanical ventilation or using natural ventilation only.
The CSIRO performance-based design methodology has been applied to large shopping centres with multi-level above and underground car parks with interconnecting ramps. When the model was applied at the design stage, CSRIO was able to predict the ventilation requirements to assist in the optimum design of traffic routing, the amount and location of wall and roof ventilation openings, the number and location of exits, etc.
For example, in the choice of external louvres for the façade of a multi-level car park, the hybrid ventilation model is able to predict the available natural ventilation flow rates due to wind pressures by modelling the porosity and spacing of the louvres.
Source: Building Products News.