When Allen Jack+Cottier principal, Michael Heenan, first walked on to Milson Island to begin the process of designing a sport and recreation hall, he did so without preconception.

Instead, he carefully considered the site conditions and allowed these to shape the building.

Aerodynamic analysis revealed that the channel carved through the spectacular sheer rock faces by the Hawkesbury River bends the breeze up and over the island.

“So, we designed the building shape to react to this more constant breeze,” says Heenan. “We knew we had the opportunity to harness it for natural ventilation.”

The wing-shape of the roof creates suction, which is used to draw hot air out of the building through roof turbines, creating an internal cooling effect.

Air is drawn into the building through low-level louvres, which run the length of the building, and over large shaded and moist river stones that enhance the cooling effect.

Heenan pushed hard to place the hall amongst bushland rather than in a clearing, in order to camouflage it from the adjacent Milson’s Passage residents.

The building’s roof design, which extends toward the ground, becomes a protective shell and fire deterrent skin, wrapping the entire building.

The roof also deflects tree debris, which collects on the ground alongside an in-ground rainwater gutter that lies beneath a filtering stone garden.

The design was enough to extinguish fire hazard concerns and the hall nestles deeply into a thick clump of trees.

Photography: Nic Bailey

Read the full story on Milson Island Indoor Sports Stadium in Indesign #48, out now.

Allen Jack+Cottier
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