Resilient toward the future

Regional office Alliander Westpoort in Amsterdam is the tallest wooden office building in the Netherlands with its seven floors. The building has won several awards, including the National Timber Construction Prize and the Amsterdam Architecture Prize (AAP) 2024. Although Alliander Westpoort has a wooden character, the facade is dominated by metal and glass. An impressive feat of craftsmanship by three facade parties, including Blitta Gevelystemen, which even initiated a fire test especially for this project. In fact, no system house had a fire certificate of such a size fixed glass-frame combination on the shelf. 

Alliander Westpoort consists of an office building, workshops, warehouses, test rooms, a training and parking building for 700 employees. The new regional office is a design by De Zwarte Hond and is characterized by "a rhythmic alternation of buildings and interspaces positioned on the lot like a barcode." The eye-catcher is the seven-story office building at the head, visible from the A5. But the work buildings and storage areas have also been designed with the same care as the office building and woven together into a robust whole. According to the architect, the building therefore embodies a high degree of flexibility, scalability and modular design.

Sustainable and circular

An all-wood structure was designed for the office building and training facilities that is flexible, creates a healthy working environment and stores as much as 1,195 tons of CO2. The parking building can grow or shrink thanks to a demountable structural design. This makes the regional office resilient toward the future. Sustainability and circularity are therefore important pillars in the design. As many circular materials as possible were used and as few harmful substances as possible, such as glue, pur or sealant. The building is naturally natural gas-free, but also energy-neutral. Rich planting ensures that not only humans but also all kinds of insects, birds, amphibians and small mammals feel at home in the grounds. 

Facade Partners

Blitta Gevelystemen also feels completely at home in Amsterdam's Sloterdijk III harbor district.   

"Several years ago, we made the façade of the prestigious Edge Amsterdam West, a stone's throw from Alliander Westpoort, in this area," says Sanneke Kettenis, commercial director at Blitta Gevelystemen, with appropriate pride. "For Alliander Westpoort, we were initially asked by Dura Vermeer to take care of the complete facade. Because of the diversity in facade construction with a significant percentage of HSB elements and weather-resistant Corten steel, we preferred to take on the facades with two partners, where we brought the three parties together at the front and were responsible for the delivery and assembly of the frames and curtain walls. So we had three at the table together with Verhoeven Timmerfabriek and VPT Versteeg for the corten steel."

Special test setup

The facade of the office building is characterized by large areas of glass, especially at the ends. "What we as Blitta have been very busy with at the front is to provide a suitable solution for the requested dimensions of the glass in relation to the specified fire requirements," says Sanneke. "No system house had a fire certificate on the shelf for such a size frame of 2.3 by 3.2 meters. In addition, we were almost at the maximum size glass that can be produced at all in 30-minute fire resistance. We then offered the contractor and architect two options: either add an extra style that would divide the glass area or perform a fire test. So it became the latter. Because of our knowledge and experience with previous project-specific fire tests, we were able to fairly quickly clarify the process and the costs. This was approved by the client, after which we were able to set the entire process in motion. What was also special about this test was that we also included part of the HSB construction and the perimeter connection in the test setup, which then passed the fire test with flying colors."

Extensive prefabrication

Blitta Gevelystemen worked exclusively with Schüco's aluminum systems, namely the AWS 75.SI+ window system, the FWS 50 S curtain wall system and the AWS/ADS 65 window and door system. All systems are finished in the color RAL 8019 with 30% gloss level. "Because of the wooden support structure of the headquarters and training facilities, it was important to seal the facade as quickly as possible," Sanneke rightly states. "The facade was prefabricated as much as possible, and then of course it is of great added value that we are practically neighbors of Verhoeven Timmerfabriek. This allowed us to assemble our frames with glazing into the HSB elements quickly and with hardly any additional transport movements. On demand, the elements were transported to the construction site ready-made with special transport. Only the glazing for the elements on the first floor we assembled on site, due to the substantial size of 4.5 meters and an increased risk of breakage."

Corten steel

The aesthetic shell of weather-resistant Corten steel was also installed on site. "The office building was already wind and watertight at that point," assures Sanneke. The three facade partners consulted among themselves quite a bit to make the aesthetic shell feasible. "Corten steel is a heavy load for the facade. Therefore, not all elements are anchored to the facade, but additional supports have been developed where the corten steel leans off at ground level." At the parking garage and the work building, that load was less of an issue because of the nature of the structure and limited height. "Here, however, we did supply and assemble another considerable number of square meters of shed roofs and window and door systems, executed in Schüco AWS/ADS 65. These, too, were prepared largely prefabricated." 

Sanneke looks back on a fantastic end result. "That is partly due to the fine cooperation with all parties and understanding of each other's profession. During the preliminary phase we visited all the parties together with the client, architect and contractor to get a good impression of the various techniques and areas of expertise. That has paid off handsomely during the rest of the project."