The clients decision to undertake wind tunnel testing for the initial design of the Concourse in Chatswood and also for the revised design, clearly demonstrated the benefit of carrying out the wind tunnel analysis for the project, said Kevin Peddie Senior Engineer at Windtech Consultants.

The importance of carrying out the testing was both to ensure the design had correctly accounted for the localised wind effects for patrons and for the design of the natural ventilation system and facade.

But also from the cost perspective wind tunnel testing enabled far more accurate design loads to be obtained which would not have been otherwise achieved through other methods such as the wind code.

Some of the major challenges of the project include ensuring the constructed development matched the architectural design of the project. Additional verification testing had to be carried out to ascertain the impact of issues which arose during the construction phase on the analysis, including louvre opening parameters.

Further challenges was being able to accurately account for the drag loads and over-turning moments on the main feature tree during strong wind events.

The change in the tree’s aerodynamic profile had to be taken into account for varying wind speeds to provide the correct results for the arborist in their analysis of the required soil depth for the root system.

By fjmt engaging wind consultants and utilising wind tunnel testing, the proposed treatments provided tailored solutions to mitigate the wind effects within and around the site as well as provides adequate natural ventilation for the atrium space.

The effectiveness of these measures was verified following construction.

Windtech’s role was critical in the minimising the reliance on mechanical means of ventilation and hence reducing the carbon footprint of the development.

The wind tunnel testing of the façade cladding became part of the cladding tender specification. The louvred openings and roof vents were specified based on the analysis carried out by Windtech for the natural ventilation study.

Windtech Consultants undertook wind tunnel testing to accurately determine the following wind effects:

1) Expected wind conditions for pedestrian comfort which would be experienced within and around the Concourse site. This included recommending treatment solutions to mitigate wind effects. These treatments mainly involved screening and strategic planting.

2) Windtech also carried out a wind tunnel study of the façade and roof cladding pressures which is essentially a value engineering exercise to minimise the cost of the cladding for the project as well as provide more definitive estimates of the wind loads rather than go off notional estimates from the wind code.

The usual feedback we get from contractors is that the wind tunnel study tends to shave between 5 percent and 30 percent of the cost of the façade package, depending on the extent of shielding and type of construction. More importantly, wind tunnel testing was able to provide greater certainty regarding the expected loading due to wind.

3) Windtech also carried out wind tunnel testing to accurately determine the wind-induced structural loads on a large LED screen proposed on the elevated platform.

4) Windtech also carried out the natural ventilation study for the atrium areas of the project to help reduce reliance on mechanical means to ventilate the atrium space.

This study recommended intake and exhaust vents in certain strategic locations to mobilise the effect of the prevailing winds for the site to provide natural ventilation to achieve both adequate air quality and sufficient flow to flush out smoke in the event of a fire.

Windtech was able to liaise with the builder’s design manager at AW Edwards and the architect FJMT to develop a passive ventilation system for the atrium volume that negates the need for any mechanically assist ventilation.

5) Windtech analysed the reflectance of the glazing elements and their impact on drivers

6) Windtech were able to combine local extreme wind speed measurements with measured drag coefficients of trees of similar species to determine the wind loads on the feature tree that is to be planted above the underground car park level of the development