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Dynamic façade changes translucency

A new greenhouse in a Danish botanical garden has the remarkable property of being able to change its translucency and regulating daylight.

It does this by pumping air in and out of polymer pillows, which expand and contract accordingly. Each pillow is made of double-layered ETFE and each layer has a foil, with a printed pattern of circles, on its inside.

Using a pneumatic pumping system, the pressure inside the pillows can be adjusted. As the layers of the pillows change position, the foils overlap to cover each other and decrease transparency. With the façade fully opaque, heat retention is increased. In total, the ETFE façade covers around 1,800 m2.

The 17,5m high structure consists of ten steel arches. These cross each other to make rectangular shapes, which are filled in using the polymer cushions. These cushions puff out with air to form the insulation for the hothouse.

Designed by Danish office C.F. Møller, the bulbous structure looks a little like a bio-dome, such as built for the Eden Project in the United Kingdom.

There’s a good reason for this geometrical form. Dome shapes are highly energy efficient, as they come close to maximising their volume to surface area ratio. This means less heat loss per square meter of façade, which is particularly important in botanical gardens.

In this case, the dome’s apex is angled slightly towards the north. This further increases the surface area on the south side, meaning a higher light influx on sunny days.

More on the project via the architects, C.F. Møller. The engineers are Form-TL.