Dubble bubble dome will be world's largest tropical greenhouse

Tropicalia exterior
© Octav Tirziu

Solar powered dome in France will cover five acres.

A giant plastic bubble is being built in the north of France; the architects, Coldefy & Associates, call it the world's largest single-domed tropical greenhouse. According to ArchDaily:

“Tropicalia” will cover an area of 215,000 square feet (20,000 square meters) featuring a tropical forest, turtle beach, a pool for Amazonian fish, and a one-kilometer-long walking trail. The biome aims to offer a “harmonious haven” where visitors are immediately immersed in a seemingly natural environment under a single domed roof.

Tropicalia interior© Coldefy & Associates

The dome is made of 200 foot long by 13 foot wide strips of double-walled EFTE (Ethylene tetrafluoroethylene), the long-lasting miracle plastic that was used at what I thought was the world's biggest tropical greenhouse, The Eden Project. However, its tropical dome is actually built up of multiple connected domes and only covers 15600 square meters (167,917 square feet.) EFTE is interesting stuff in that it is very long-lasting, is recyclable and has a low embodied energy. KieranTimberlake Architects used it on the U.S. Embassy in London for sun shading, and it has been widely used for stadium roofs.

interior with lake© Coldefy & Associates

Greenhouses usually take a lot of energy to heat in winter and are extremely hot in summer, but being a dubble bubble, this will hold the heat and may even generate enough through solar gain to warm the other buildings.

This double insulating dome will protect the tropical ecosystem in summer and maintain its temperature in winter. The partial burial of the greenhouse will reinforce this insulation. The excess heat can therefore be directly used, stored or redistributed to our neighbors as part of a network of private heat or a "smartgrid." - Denis Bobillier, Technical Director of Major Projects, Dalkia

Dalkia is an energy services company supplying heating and cooling systems and has invested in solar and biomass energy, and is a partner in the project.

Interior of dome © Coldefy & Associates

The dome will evidently be an “exceptional oasis for tropical flora and fauna” beneath.

Visitors are led along a kilometer-long path, encountering an 82-foot-high (25-meter-high) waterfall, 82-foot-long (25-meter-long) “tactile pool” filled with koi carp, and an Olympic-sized pool filled with Amazonian fish, some growing up to 3 meters in length."

Crystal PalaceCrystal Palace Exterior/Public Domain

This bubble is big, but for context, at 20,000 square meters it is a quarter the size of the Crystal Palace built in 1851. Designer Joseph Paxton also had to deal with solar gain, according to Wikipedia:

Crystal Palace InteriorCrystal Palace Interior/Public Domain

To maintain a comfortable temperature inside such a large glass building was another major challenge, because the Great Exhibition took place decades before the introduction of mains electricity and air-conditioning. Glasshouses rely on the fact that they accumulate and retain heat from the sun, but such heat buildup would have been a major problem for the Exhibition, and this would have been exacerbated by the heat produced by the thousands of people who would be in the building at any given time.

I wonder if the Tropicalia bubble might not get a bit too tropical in summer.

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