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Steel and glass define a public-facing greenhouse that pushes the scale of urban agriculture

By Chris Walton •

Built atop an existing concrete office building, the Agrotopia greenhouse pushes the limits of urban agriculture in Belgium. Covering 9,500 square meters (102,000 square feet), the greenhouse—designed by META architectuurbureau and van Bergen Kolpa Architecten—juts out from the city of Roeselare’s skyline, making a statement with an all-glass-and-steel structure designed for both visitors and vegetables.

The building provided areas for the cultivation of fruits and leafy vegetables in four climate zones as well as research facilities for Inagro, the Flemish research institute for agriculture and horticulture, and REO Veiling, a produce distributor. Public walkways link the programs to provide an educational opportunity to visitors. REO Veiling’s headquarters occupied the pre-existing office building upon which that Agrotopia was built, and the project received support from the Flemish government.
The scale of Agroptopia pushes the limits of urban agricultural production. (Filip Dujardin)

The facade and roof were a standard aluminum greenhouse system with diffuse glass. Optimizing for agricultural production, and working with researchers at Wageningen University, the design team chose diffuse glass with a particularly high haze factor, increasing crop yields by up to eight percent by allowing sunlight to better reach the plants. An entrance staircase moves visitors to the central square of the greenhouse’s interior.

Glass windows span the entirety of the greenhouse, allowing for both views into the building and sunlight for crop growth. (Filip Dujardin)

The facade along the building’s entrance is comprised of vertical glass bay windows, with screens that provide sun shading and reduce energy consumption. According to van Bergen Kolpa Architecten owner Jago van Bergen and managing partner Niklaas Deboutte of META architectuurbureau, “the screens can be controlled in two independent directions, rotating with the sun from east to west, so that half of the facade always remains open and transparent to view,” a move that maintains the public-facing character of the structure. Furthermore, pipes for the greenhouse were integrated through the steel facade columns on this face of the building. 

The facade’s transparency is emphasized from the interior as well. (Filip Dujardin)

On the west side of the facade, the greenhouse’s horizontal construction provided significant exposure to sunlight for crop growth, and reflection-free views from the ground level. The facade on this side rose twice the height of the other faces of the building, providing spaces for vertical cultivation and storage for rainwater collected from the roof. The two cantilevered faces of the building owe their “striking appearance to the expressive, faceted façades in transparent glass,” said van Bergen and Deboutte.

Drawings detail the multitude of functions within Agrotopia, making it a self-sustaining environment. (META architectuurbureau and van Bergen Kolpa)

Mounting the greenhouse atop an existing concrete structure was a challenge, particularly for a team that values sustainability. The bearing lines of the steel structure had to align with the concrete structure, and given the need to slope a greenhouse roof, the steel structure was mounted at a slope. An elevated, flat concrete-tiled floor was applied after, and covers supply lines for nutrient water, a discharge line, a return pipe for water circulation, and the carbon dioxide supply. Adjustable feet were designed for the base of the steel columns, allowing for ten centimeters (four inches) of expansion per hundred meters of facade in order to account for expansion and contraction between the summer and winter seasons.

Public pathways are cooled to provide occupant comfort in a system that is contained entirely within the building. (Filip Dujardin)

The most impressive aspect of Agrotopia is its self-containment. Run-off from irrigation is recycled, allowing for a fully contained system, and surplus heat from a waste incinerator elevates the temperature of the interior. The spaces through which visitors circulate are surrounded by a “buffer climate,” that also includes offices and meeting rooms. The temperature of the public spaces is controlled via evaporative cooling when thermostat would otherwise become unreasonable on hot days. The designers described the climate control as a process of “circular symbiosis with the city.”

Details of the building’s technical features are integrated into multiple programmatic sections of the building. (META architectuurbureau and van Bergen Kolpa)