Decentralization and Integration

With the goal of environmental transparency in mind, Murphy/Jahn designed the Bayer Headquarters in Leverkusen, Germany with an active, environmentally responsive facade. A double skin creates environmental buffers and zones of control to address occupant comfort (Fig. 5.4).

Figure 5.4 - Inside the double-skin wall of Bayer Headquarters

To provide solar control, 12-inch- (30-centimeter) wide perforated aluminum louvers were located between the two glass walls, exterior to the occupied space. The perforation pattern was carefully designed to maintain visual connectivity to the exterior while minimizing glare and insolation. The ends of the building, without double glass walls, are shaded by an exterior metal mesh. In both cases, direct solar gain is blocked so as not to produce a secondary radiant heat load in the occupied space.

Between the two glass walls of the double skin develops a laminar air flow that further controls heat transfer. The louvers separate two layers of air. The outermost layer is heated by sunlight on the exterior glazing and the blinds. This heated air moves up due to a natural chimney effect and exits through outlets at the roof. This convection is fed by fresh air entering via inlets at the underside of the glass "shingles."

The inner layer of air is cooler, introduced through ground ducts to the interior side of the blinds. This configuration draws air into the occupied space across tempering fin-tube convectors, creating a comfortable temperature-controlled natural ventilation. Radiant coils within the exposed concrete ceiling are the main source of temperature control, reducing the role of air as a temperature-exchange medium.

The lower air volumes required result in lower velocities, allowing natural stratification to separate the heated air for extraction at grills placed high in the room. An under-pressure air system or fan box draws the ventilation air over the fin tubes at each module. A low-volume distribution system transmits the required hygienic ventilation air at a base level temperature, allowing the tempered exterior air to be controlled by individual occupants, according to their choice for both air volume and temperature.

The inner wall contains operable windows, which may be controlled by the occupants. These allow for the influx of large quantities of fresh air when exterior conditions allow. The venting of the buffer zone can be modulated to extend the period throughout the year when exterior or buffered exterior air is suitable for natural ventilation.

Murphy/Jahn extended the principles established in the four-story Bayer Headquarters to the 40-story Deutsche Post highrise in Bonn, Germany, where a fan-powered slab-edge fin tube convector was put into full production (Fig. 5.5). There are no interior shafts or air handling equipment.

Figure 5.5 - Deutsche Post in Bonn, Germany