In order to be able to use the innercity, listed arena in winter as well, as the city envisaged, a temporarily installable pre-stressed membrane cushion strecthes over the elliptic internal area.
The air cushion is stabilized by a thin compression ring that rests on 30 columns at a height of 9.80 m. It is “sunk” into the arena in such a way that from outside it is invisible. The upper membrane rises 8.2 m and consists of strips of easily foldable PVC-coated polyester, 1 mm thick. The lower side was permitted a sag of only 4.2 m, which is why the lower membrane is supported by a cable net. The tension stress, which is thus less, allows a membrane that is not as strong, but more translucent. The supporting cable net is connected to the columns by radial cables and can withstand a grid in the middle for loudspeakers and lighting.
An inclined facade closes the building along its perimeter. This facade consists of 480 lamella-type elements which are made of polycarbonate plates and light aluminium webs. Each of these elements spans from the (main) ring to a second ring which is also referred to as the lower ring. The facade is transparent and it can be opened completely in order to allow natural ventilation.
The roof is extremely lightweight and can be completely dismantled so easily that at the beginnign of the summer season it can be taken down within a few days (including the ring), before being re-erected in the fall within three weeks.
