The historic post office was made as sustainable as possible for its conversion into a museum. An integral design was created through close cooperation between the architect, building physicist and systems engineer. This ensured that, for example, the building is now gas-free and has an indoor climate that is suitable for a museum, while at the same time the historic value has been preserved, which was one of the challenges that had to be met when the building was redeveloped. Low-temperature heating can be adjusted for every room, while low-temperature cooling has also been applied to meet the climate requirements in depots and museum rooms. An air-water heat pump generates heat and cold for the building and has been designed in such a way that it can be connected to the adjacent building complex in the future. The roof has been insulated, plastic window frames have been replaced by aluminium frames in renovation profiles in accordance with the original image, and new retention walls insulate the inner shell of the building that was built in the 1930s.

New additions also have sustainable and circular designs. The sculptural art window, one of the two new prominent features of the museum, has been clad on the outside with aluminium shingles. A fully recyclable product, with a long life and low maintenance requirements. The shape and the folds refer to envelopes, which is a tribute to the history of the post office. The inside has been finished with bamboo that seamlessly follows the organic form. In addition to this art window, the new park entrance is the second, contemporary feature. An intermediate section at a corner, built in the 1980s, has given way to a contrasting, inviting and transparent entrance that has also been clad with folded aluminium ‘envelopes’.

The historic stairwells have been restored and function as the pivot for logistics activities in the building. These stairwells have been supplemented with a new steel staircase towards the roof. Its stairs are removable and made of prefabricated cut blue steel that were assembled on site. A unique and circular product was developed for the interior cladding of the entrance desk and the museum bar, among other things. Regional construction waste was used for manufacturing the tile. The glazed finishing was made from a residual product from a local glass factory, without any artificial colourants. This concept applies for all materials used, from anodised aluminium shingles as facade cladding, bamboo cladding in the art window, blue steel stairs and bi-composite entrance panels to recycled cloth air ducts. This results in a natural colour palette, for both the interior and the exterior.