CASE STUDY | EDGE SUEDKREUZ The solution to keeping the office floors comfortable was developing a bespoke, highcapacity hybrid active chilled beam. control of their environment if they can open a window, explains Elze. To help limit heat gains on the office floors, the full-height glazing incorporates solar protection film. This incorporates a small mesh to provide shading from inclined sunlight while allowing horizontal views out. Its a passive system that works like a louvre, says Elze. In addition to the ventilation, the majority of the piped services are distributed to the floor plates through risers contained in the central concrete core. On leaving the riser, pipes and ducts enter the floor plates through the dropped ceiling of the adjacent toilet blocks. On office floors, the ceiling height is 3.0m to the underside of the wooden beams, 3.05m to the underside of the chilled beams. However, in the toilet areas, the ceiling height has been dropped to 2.3m to create space to allow pipes and ducts to be re-routed before entering the office floor. Office floor plates are intended to be mostly open plan. There is, however, a central spine on each floor where the ceiling height has been dropped to 2.6m to enable ductwork and pipework to be distributed on the floors. Office floors are designed to be predominantly open plan Elze refers to this as the corridor because the dropped ceiling follows the same linear route along the centre of the floor plates as a corridor would, should partitioning be installed. There is a 40cm space above the toilets to re-route the services and bring them into order before they go into the corridor dropped ceiling, he says. Internally, all of the office floors are linked by a giant, 1.600m2, 26m-high square central atrium that includes a series of striking timber-clad concrete trees soaring up to 15m high. Special care has been taken to ensure a comfortable environment in this area (see panel, Cooling the atrium). Managing the electrical loads Beneath the building, a giant reinforced concrete underground car park connects COOLING THE ATRIUM The central atrium features a series of flying staircases bridging between the floors and four free-standing timber-clad concrete trees. The tallest of these is almost 15m high, the shortest 4.5m. This atrium gives the building its character; it provides spaces for both formal and informal meetings, including seating spaces in the trees, along with seating on the ground floor for the cafe. The atrium also includes a loggia on level 5, where there is a sky lounge and access to an external roof terrace. Detailed modelling simulations ensured comfort conditions are achieved through a combination of passive and active design solutions. These include moveable foils within the ethylene-tetrafluoroethylene (ETFE) roof pillows (ETFE material is extremely low weight compared to glass and offers exceptional light transmission) to control the amount of solar radiation entering the atrium in both summer and winter. There are also additional openings directly beneath the roof on the north and south elevations to exploit the wind direction to remove hot air from high levels in the space. To ensure the atrium remains comfortable in summer, Buro Happold amalgamated various cooling systems, including: underfloor cooling; cooling from cylindrical air diffusers in the corners of the atrium; and displacement units set into the floor of the seating areas on the trees. In addition, cooling units above the entrances supply conditioned fresh air; these are connected to roof-top air handling units via run-around coils. We did a lot of energy studies for the atrium in order to determine what cooling we needed; with energy simulation modelling we were able to trim the cooling down to figures that are sensible, says Elze. Cooling is provided by two hybrid cooling towers mounted on the roof. 76 November 2022 www.cibsejournal.com CIBSE Nov 22 pp74-76, 78 Edge Berlin.indd 76 21/10/2022 16:46