Car Park Ventilation
The need for car park ventilation stems from two key concerns: controlling carbon monoxide (CO) from engine exhausts and smoke from a fire. The concentrations of both these types of contaminants can be evaluated using Vipac’s methods to help optimise the natural ventilation system.
Carbon monoxide is an issue compounded when the car is idling or moving at low speed after having been started from cold. Through Boundary Layer Wind Tunnels and Vipac’s algorithms, our Wind Engineering Group provides expert evaluations of their effect on the overall emission into the space. For wide area and background pollutant evaluations, see our Air Quality page or to watch Vipac being interviewed by Channel 9 News, click here.
Working hand-in-hand with the project’s traffic engineers and the design team, Vipac also offers professional design assistance for the performance of naturally ventilated, conventionally (mechanically) ventilated, and newer hybrid systems, including fan-only (and ‘impulse’) systems. Our analysis considers:
- Whether the car park is elevated or underground
- Whether it’s a single or multiple compartment
- What the floor plan and details of the layout are
- Whether there are ventilation or access openings
- Whether there are ducted or free supply and exhaust locations
- The nature of any recirculation devices
- Whether there’s any spill of air from adjacent spaces
- Management operation of the monitoring and control systems
Best Industry Practice
Vipac applies a range of codes and standards related to acceptable levels of CO concentrations in the air, these might be 400 parts per million (ppm) over a minute, 60 ppm over an hour, and 30 ppm over an eight hour average.
The Vipac Difference – Using Intelligent Design to Improve Performance
There are two types of design methods for National and International standards – namely ‘deemed to comply’ (bespoke) and ‘performance’. While a bespoke method may nominate permanent wall openings to provide cross flow ventilation, anticipated performance method is applied through simulation, known as fluid flow analysis. This method assists designers achieve performance over larger area car parks, at lower capital cost, and with less operational energy than for bespoke design systems.
Step 1: Desktop Study
A good initial step to evaluate candidate layouts, understand potential complications and incorporate recommended design alterations, a Desktop Study is based on experience, previous studies and a literature survey. For simple cases, a Desktop Study may be sufficient to evaluate the car park ventilation.
Step 2: Wind Tunnel Study
To grasp the fullest possible picture on pollutant dispersion, a Wind Tunnel Study is recommended. It provides the most comprehensive information on pressure distribution on the façade that, once integrated with the local wind climate, allows Vipac to predict the average air changes achievable for a particular design.
Other Considerations and Influences
- Nearby and neighbourhood buildings that interact with the local wind flows
- Exit vs entry movements
- Keeping the aircon running
- Proportion of diesel vs petrol engines
- Fleet mix (range of engine size)
- Travel distances (find a spot, distance to exit).