In the fully glazed “AutomationCenter” at Festo AG & Co. KG, an exhaust air façade minimizes cooling requirements. The ideal indoor climate is ensured by the combination of concrete core activation and underfloor convectors, which ventilate, heat or cool quietly as required. Thanks to the so-called mixed-source ventilation, the floor units work extremely efficiently while remaining visually and acoustically unobtrusive.

The new AutomationCenter of Festo AG & Co. KG in Esslingen proves that transparent architecture and energy-efficient operation are not mutually exclusive. Despite the single-skin, glass façade, the building managed to meet the requirements of the EnEV. An innovative exhaust air façade is used here to minimize solar input. It has a glare shield between the glass front and the interior. It forms a separating layer to the rooms, the surface of which assumes approximately room temperature, so that the employees of Festo Vertrieb GmbH & Co. KG working here have no feeling of radiant heat. The glass façade and glare protection simultaneously form a cavity through which air is extracted. In this way, not only is warm air removed that would otherwise accumulate behind the glass in the sunlight, but the exhaust air from the office floors is also disposed of via the cavity (and also via the two stairwell cores). For heating and cooling, Festo relies on regenerative energy, concrete core activation and unobtrusive room units for ventilation and zone-specific temperature control.

For the air exchange in the offices, meeting rooms and other rooms, ventilation centers provide conditioned supply air, which is fed to the room units through ducts in the raised floors. During office hours, an average air exchange rate of 30 m³/h per person is aimed for. The air volumes can be regulated separately for the east and west sides via two volume flow controllers per floor. This also applies to the room temperature, so that the temperature zones can be controlled independently for different internal loads or depending on the amount of sunlight. Room units from LTG Aktiengesellschaft, Stuttgart, provide the zone-specific climate.

More than 600 LTG VKB floor fan coil units with fresh air connection are installed close to the façade to ventilate and control the temperature of the office areas. Think tanks are available to employees as room-in-room systems for meetings and to “recharge their batteries”. To ventilate and cool these rooms, LTG has developed and supplied 60 fan coil units in a special design with 240 connected LDU floor slot diffusers. High-induction LTG ceiling slot diffusers type LDB were chosen to supply the restaurant and cafeteria with conditioned supply air.

Stainless steel covers for an elegant look

To ensure that the transparent and clear architecture of the outer shell can be continued in the offices, the ventilation units had to meet high aesthetic standards and blend in discreetly. The underfloor fan coil units meet this requirement with high-quality stainless steel covers in LTG system design. The frames of the façade units were specially adapted for the Festo high-rise and have the color of aluminum.

Some of the floor convectors have already been arranged in such a way that it would be possible to divide up the office space differently, for example by setting up some single and double offices close to the façade. Thanks to the raised floor, it would also be possible to retrofit additional appliances with the same appearance to suit a different use. In general, however, the building concept follows the principle of avoiding interior walls and thus mixing the teams. Open-plan offices therefore account for the largest share of the gross square meter area (12,000 m²) at 5,000 m². Only around 200 m² are individual offices.

The design of open-plan spaces is not just a visual issue; acoustics also play an important role. Sound should not spread unhindered and the noise level of the building technology must be low enough to allow comfortable working conditions. This places high demands on the ventilation technology, as it has to supply fresh air effectively and quietly and dissipate heat, even on hot summer days with temperatures of up to 40 °C. The fact that this performance is available was demonstrated in summer 2015: The room temperature did not exceed the specified maximum value of 26 °C on any day.

On such hot summer days, in addition to the cooling provided by the concrete core activation, support from the floor convectors is essential. They operate with dry cooling, i.e. at a flow temperature of 17 °C, in order to avoid condensation on the pipes of the cold water circuit or on the appliances and to make efficient use of regenerative sources. This has the advantage that the cooling air flowing into the room is not so easily perceived as cold and draughty, but requires a high volume of air to be circulated to achieve the desired cooling capacity. The fans must therefore be able to handle a high air circulation rate at a low operating noise level.