The Glaspalast in Sindelfingen, an indoor sports arena, was built in the years 1974 to 1977 by architects Günter Behnisch & Partners and had been in use without major repairs or refurbishment ever since. More than 40 years later, however, it had finally become necessary to subject the building to a substantial overhaul and to bring it up to today’s technical and ecological standards. One premise was that the measures would not interfere in a big way with the existing qualities of the hall. The objective was the preservation of the character of the building whilst transforming its qualities to present day standards. The planned refurbishment focused on two main points: The roof was optimized in terms of its energy performance and technical construction, the shed roofs, to which the Glaspalast owes its epithet, were improved in terms of their aesthetic appearance, energy efficiency and lighting quality.

During the renewal of the roof, which over the years had acquired problems with leakage, special priority was given to improving its energy performance by increasing the insulation thickness. The missing vapor barrier also had to be added during the refurbishment. After some thorough research a white roofing membrane was chosen on account of its advantageous properties to minimize energy input of the building. As the indoor arena also functions as a venue for conventions and other events, it was important to maximize the use non-combustible material for the roof structure. The selected foam glass insulation consists largely of waste glass and meets the required characteristics. The roof build-up comprises of a fully adhesively bonded, water-tight compact roof system consisting of white FPO waterproofing membrane with bituminous underlay. Thanks to its high degree of reflection, the white FPO waterproofing membrane can lead to dramatically lower energy gains.

Together with the company Bartenbach lighting design a product was sought for the shed roofs that would meet several requirements simultaneously. One important criterion for the shed roof, for example, was to achieve an optimal result for sports and other types of events with a light-flooded hall that would have no distracting glare or shading effects. The product used in this case is tempered double glazing which is filled with argon gas and covered by a complete capillary layer to provide additional protection against the sun and disperse the light in the glass cavity. In addition, the width of the glass panes is twice as large as that of the previous glazing. This should help to prevent heat and size-induced stress, which used to be a recurring problem with the former glass elements. In order to provide full shade against the sun, solar shading elements were mounted inside the shed roofs on the north and south sides. In addition to other purposes these serve to direct additional light from the north side into the building by utilizing the reflection of the blinds on the south side.

Thanks to these measures a result was achieved which created ideal, minimal distraction lighting conditions for sports as well as other types of events, almost without the need for artificial lighting during the day.