The snail-shaped hothouse in the Botanical Garden in Aarhus is a national icon with regard to hothouse architecture. It was designed in 1969 by C.F. Møller Architects, and is well-adapted to its surroundings. It was therefore important to bear the existing architectural values in mind when designing a new hothouse to replace the former palm house, which has been literally outgrown. “The competition sought an independent and distinctive new palm house, but it was essential for us to ensure that the new building would function well in interplay with the old one,” says Tom Danielsen, architect and partner with C.F. Møller Architects. The organic form and the large volume, in which the public can go exploring among the treetops, experience botany and take a journey through different climate zones in a way which makes the new hothouse in Aarhus an attraction in a pan-European class of hothouse architecture. An assortment of tropical plants, trees and flowers fills the interior of the greenhouse’s transparent dome, which is built on an oval base. A pond is located at the centre of the space, while an elevated platform allows visitors to climb up above the treetops.
The design of the new hothouse is based on energy-conserving design solutions and on knowledge of materials, indoor climate and technology. Using advanced calculations, the architects and engineers have optimised their way to the building’s structure, ensuring that its form and energy consumption interact in the best possible manner and make optimal use of sunlight. The domed shape and the building’s orientation in relation to the points of the compass have been chosen because this precise format gives the smallest surface area coupled with the largest volume, as well as the best possible sunlight incidence in winter, and the least possible in summer.
The transparent dome is clad with ETFE foil cushions that have an interior pneumatic shading system. The support structure consists of 10 steel archesthat fan out around a longitudinal and a transverse axis, creating a net of rectangles of varying sizes. The cushions used on the south-facing side were made with three layers, two of which were printed. Through changes in pressure, the relative positions of these printed foils can be adjusted. This can reduce or increase, as desired, the translucence of the cushions, changing the light and heat input of the building.
Botanical Knowledge Centre
The overall project also includes a comprehensive restoration of the old hothouse, in which the palm house becomes a new Botanical Knowledge Centre aimed at the general public. This will take place at the same time the complex is extended with the new tropical hothouse.
Sustainable hothouse, Botanic Garden, Aarhus, Denmark
Client: Aarhus University and Danish University & Property Agency
Architect: C.F. Møller Architects
Landscape Architect: C.F. Møller Landscape
Engineering: Steel load-bearing structures: Søren Jensen A/S; Foil cushion planning: formTL GmbH
Size: 3,300 square meters (1,242 square meters new tropical hothouse and 2,071 square meters renovation and rebuilding of existing hothouse)
Prizes: 2009 1st prize in an architectural competition, 2014 Aarhus Municipality Architecture Award