Hunter Douglas transforms innovative folding system into flat closing sun screen

Folding screens on the façade of a building often create an unusual dynamic. Treating the transparent parts of the building envelope with closed or open folding screens, in combination with varying colour nuances, lends the building an entirely different look. According to Job Hoevenaars, product manager for Sun Control Systems at Hunter Douglas, architects applying folding screens tend to want flat closing ones to create a monolithic appearance when they are closed. Hunter Douglas has responded to this need by developing its existing harmonica folding system into a fully flat closing sun screen system. The flat closing screens are outfitted with the same hinge construction as the harmonica screens, but powered by a spindle motor attached to the screens themselves, so that they can be opened and shut electrically. Hoevenaars says: “This screen can be fitted with the same dressing as the façade, so that the sun screens are hardly noticeable in a closed position. Only when the screens are opened do the windows in the façade suddenly become visible.” Hunter Douglas has taken this newly developed technique and also applied it to folding screens for curved façade elements on the front of the Fioretti College in Lisse, the Netherlands.

The construction of the Fioretti College has recently been finished. Project architect Aldo Vos, of Rotterdam-based architecture agency Broekbakema, opted for Hunter Douglas’ fixed, horizontally sliding harmonica screens. These screens are not flat closing, but stand out at a slight angle in closed position. The powder-coated aluminium panels have a 12% perforation to reduce light fall and direct sunlight. The school’s design is compact: three floors with classrooms surrounding a central court. This means all of the classrooms catch a lot of outdoor light. Project coordinator Maurice Knook of Broekbakema explains: “Without light blocking, students won’t be able to read the smart boards in the classrooms. The commissioning party was quite clear about not wanting an indoor light protection system, as these tend to be less durable. So together with Hunter Douglas we developed a sun and light control system for the façade. The screens are linked to the building management system, but can also be operated at the press of a button by individual teachers in every classroom.”

The screens are two metres high and fold outward simultaneously on upper and lower rails. They’re driven by a geared belt fixed onto the upper rail. The moving screens consists of four or five modules, each 900 mm wide and interconnected with hinges. At the top of the folding screen there is a scissor arm construction to ensure stable movement. The same folding system has been used at the rounded façade corners, only here the upper and lower rails are curved, enabling the screens to hug the corner. “In order to open and shut these screens, the harmonica construction is set in motion by spindle motors mounted on the screens to move the panels either toward or away from each other. Technically, this was quite complicated. Initially, we developed the system for flat closing folding screens, but now we’ve applied it to the rounded façade elements of the Fioretti College as well”, says Hoevenaars.

The system blocks heat as well as light. The school is a so-called ‘fresh school’ type B with an Energy Performance Coefficient value of 0.7 that makes it almost energy-neutral. “The school and the adjacent swimming pool, which is still under construction, share a geothermal heat pump. The school’s heat is transported to the pool in exchange for water, which is used for cooling the building,” says Vos. A total of 117 modules of four or five elements in various shades of green and light blue were used for the Fioretti College. The result is a very colourful façade. To add to the ‘green’ look, ivy is growing up some of the façade parts.