How to get a cloud indoors?

The climatisation of the Corderie del Arsenale was a challenging task, given the fact that the open space once was instrumental for Venetians’ ship and rope production. Transsolar saw an oppourtunity in that difficult aspect, using the historic railroad tracks spanning throughout the 400m long Corderie as an underfloor plenum which supplied cold air into the space. “An idea of which we didn’t know until the end whether it would work or not”, they say. The rooftop, too, had to be closed off, to isolate the unique microclimate from the rest of the Arsenale. A stretch-ceiling made of a polymer membrane created an airtight seal for the exhibition space without penetrating the heritage’s protected structure. Even the ramp allowing visitors to wander through the cloud incorporated the columns of the Corderie, using them as load-bearing elements for the minimalistic steel beams with thicknesses of only a few centimetres that carried the entire load of the 10 ton structure.

Creating the cloud is based on a stable temperature and humidity stratification in the space in 3 layers: below the cloud 18 – 24°C, 60% humidity, in the cloud 26 – 32°C at 100% humidity and above the cloud with 32 –38°C at around 50%. The stratification is created by an air-to-air heat pump, extracting heat from the space below the cloud and supplying the energy into the space above the cloud, both by low flow air return systems without mixing the thermal layers. A humidification system based on evaporation within the cloud creates the necessary humidity range.

“Clouds are an essential component of our planet‘s atmosphere. They are the visible part of the terrestrial water cycle, carrying water – the source of life – from the oceans to the lands. They find balance within stable equilibrium and naturally sustain themselves, embodying and releasing solar energy throughout each day, and over the course of every year. However, harnessing these natural wonders and bringing them into buildings is quite another matter.”

This is how Transsolar KlimaEngineering describe Cloudscapes, an installation allowing visitors to experience an indoor cloud based on the physical phenomena of saturated air and condensation droplets floating in an area of the Corderie del Arsenale. The cloud spans from wall to wall at a height of around 3m. To allow the visitors the experience of crossing the cloud to the space above, a 75m long ramp has been designed by Tetsuo Kondo. People can cross the cloud of approximately 1–2 m in thickness, interact with it and feel the different microclimatic conditions condensed within a few meters. The atmosphere above the cloud has a different quality of daylight and artificial light, separated from the space below by the light filter effect of the cloud.