Renewal of the Climate Greenhouse at the Hortus Botanicus

Client | Hortus Botanicus Amsterdam |
Completion time | 2019 - 2025 |
Market | Art and culture |
Team | |
In collaboration with | ZJA Architects & Engineers, BOOM Landscape, Designwolf, AKOR, CRHS, Infinitus Solutions, Vic Obdam Staalbouw, Buitink Technology, Kingspan Light + Air, Lek/Habo, Copijn, en Kloosterboer |
Location | Amsterdam |
Project scope | ~1.400 m2 bvo |
Expertises | |
Plants are returning
The characteristic waterfall, constructed from existing paving stones, is complete. Additionally, the new landscaping of the greenhouse is underway, and the preserved plants are returning from their temporary accommodation.

Roof and facades
Starting in February 2024, all plants were removed from the greenhouse. The plants that are being preserved have been placed in temporary accommodation. The facades and roof of the greenhouse have also been stripped. It is now clearly visible how slender the original structure is.
To make the greenhouse climate-neutral and gas-free, insulating, transparent lightweight air cushions made of ETFE film are being installed in the roof. The facades will be fitted with double glazing, a storage system for the reuse of (rain)water, and smart, energy-efficient integrated climate systems. This allows the Hortus to make significant progress in energy savings and reducing the CO2 footprint. Since the greenhouse is being built as a detachable structure, it is also easy to dismantle. Regardless of what the distant future holds for the greenhouse, the steel structure is ready for a new and sustainable life and can easily last a third term. By November 2024, the greenhouse will be wind and watertight again.

Construction site
In addition to all the technical challenges the project faces, the layout of the construction site is also a complex puzzle. Around the current greenhouse, there is only a three-meter-wide strip available. Therefore, all materials are delivered to the project just-in-time. Moreover, some materials are transported to the construction site via the Amsterdam canals due to the limited transport options in the city center. The construction cabins are also placed in the canal to optimize the limited workspace.
Passionate client and construction team
The Hortus wanted to open the greenhouse during Amsterdam’s 750th anniversary in 2025. That this will actually succeed is partly due to the passion of the client and an involved design and construction team, coordinated by CRHS.
Environmental permit granted
The renovation of the iconic greenhouse is one step closer: the environmental permit for the modernization of the Three Climates Greenhouse has been granted. Additionally, the structural design is now fully completed. The renovation will begin in 2024. ABT is also responsible for the technical development of several interior elements in the greenhouse. In preparation for the major move, the first plants and trees are already being pruned. This also makes it easier to measure the existing structure. The existing steel structure of the Climate Greenhouse forms the basis for all newly added elements. Because the connection of the new steel structure had to be very precise, a 3D scan was made of the entire existing structure. All data was then converted into a BIM model, in which all new components were added and checked for clashes. An additional challenge was that it was not known how the tension structure would behave after the removal of the existing roof. To ensure that all new components fit exactly, a calculation was made with an assumed spring-back of the structure. The components from the facade builder and roof supplier were also developed using the measurement model. Without the use of digital technologies such as 3D scanning and BIM, this would have been a complex and time-consuming task.

Special main load-bearing structure
In recent years, extensive work has been done on the new design. The designers have succeeded in preserving the existing characteristic main load-bearing structure while meeting the current stricter requirements for sustainability, accessibility, and light transmission. Thanks to ABT’s advice, the principles of the original design—lightness and slenderness for optimal daylight entry—have been maintained, with even more focus on the special main load-bearing structure.
New roof structure
The roof will be equipped with lightweight insulating 3-layer ETFE air cushions; the structural motivation behind the ETFE roof is that the roof weight, unlike a roof with (safety) insulation glass, remains virtually unchanged compared to the original single-layer glass greenhouse roof. This prevents the existing structure from being overloaded. Moreover, the ETFE air cushions provide good insulation properties and light transmission.
ETFE cushions are multi-layer membranes that are inflated with a slight overpressure. This gives these cushions strength and stiffness to withstand loads from wind and snow. This membrane action results in vertical forces and horizontal forces acting on the adjoining structure. The existing main load-bearing structure of the greenhouse is extremely suitable for absorbing vertical loads but not for absorbing horizontal loads parallel to the roof plane. Additionally, the center of gravity of the horizontal force from the ETFE cushions acts at least half the profile height of the roof girders higher, creating torsional moments relative to the roof girders. Furthermore, by removing the original glass roof, including the auxiliary steel, the support against buckling and tipping (around the weak profile axis) of the roof girders (IPE240) has disappeared. This unsupported length could reach up to about 16 meters.
Additional construction is therefore required. Several options were considered, and ultimately, it was decided to place extra steel profiles on top of the current roof girders. These are flat tubes, which have good torsional properties (insert figure 4). The width of these tubes is adjusted to the unsupported length in the horizontal direction.

Renovation decision made
The decision has been made: the iconic Three Climates Greenhouse of the Hortus Botanicus will be renovated. The Three Climates Greenhouse on the Nieuwe Herengracht dates back to 1993 and has since been a prominent and recognizable icon in the center of Amsterdam. With its ingenious combination of components from production greenhouses in the Westland and an external skeleton that gives the structure its strength through tension rods on the roof, it is a flexible and functional home for the famous plant collection.
Nearly thirty years have passed since the greenhouse was built, and the present day imposes new requirements, particularly focused on reducing energy consumption and transitioning to more sustainable sources. The decision has therefore been made: the greenhouse will be made more sustainable and redesigned. With this renewal, the Hortus aims to create a fully sustainable greenhouse that provides optimal shelter for the plant collection, is future-proof, and tells the story of biodiversity. Just as in 1993, ZJA is providing the architectural design and ABT the structural advice.
Header image: design of the new Climate Greenhouse, © ZJA Architects & Engineers
