Putting a new front on services design
If the design of building services is considered early enough, it can almost become part of the building fabric rather than added later — with considerable benefits, as a landmark building in Germany demonstrates.It is generally the lot of the building-services designer to be presented with a building and asked to design the services. And the string of requirements usually includes minimum space for services, maximum flexibility, the best possible comfort conditions and minimum energy consumption. Far better for the building and its services to be designed as an entity, which is just what happened with a major development in Dusseldorf — with the integration of ventilation and comfort cooling into the façade itself? Client driven It will come as no surprise to learn that the project was client driven, enabling ventilation and air-conditioning manufacturer Trox GmbH to work with building-envelope specialist Schuco to develop the facade for this building. Capricorn House is in the Media Harbour close to the River Rhine. It is a 7–storey building with four basement levels and potential office sizes from 270 to 22 700 m2. The total amount of space available for offices is 18 411 m2, with a further 3580 m2 of shop space. There are also over 500 parking spaces. Tightly integrating the services and the façade enables ventilation and cooling around the building perimeter to be delivered from units that are all 1 m high, 1 m wide and just 190 mm deep from front to back. 850 bespoke FSL units have been installed in this building, which was designed by German architects Gatermann + Schossig. Provision for drawing in fresh air and exhausting stale air for each FSL unit are incorporated into the façade panels at low level as part of the prefabrication stage, with Trox supplying the sill units to Schuco. At a later stage in the building’s construction, the indoor units were mounted and connected using quick-release couplings to pipework supplying chilled water and hot water. The indoor units have separate fans for supply and exhaust air, an energy recovery unit between the two airstreams, F6 fine dust filter and dampers to control the airflows. Air is delivered into the room at low level at displacement velocities with a reach of 6 m. Return air comes in through the sill trim above the unit and is filtered. Energy-efficiency strategy By making possible cooling overnight, energy recovery between supply and exhaust airstreams and free cooling, the Trox FSL units make an important contribution to the building’s energy-efficiency strategy and integrate with heating and cooling systems served by heat pumps using ground water for heat supply and rejection — or even to provide free cooling. The building has been designed with a primary energy requirement 20% lower than the German energy-saving regulations. The role of a Trox unit is to draw in fresh air directly through opening in the façade, with a motorised shut-off damper closing the inlet when the unit is not operating. The exhaust-air damper is coupled to the inlet damper, so that both are operated by one actuator. The fresh air is cleaned using an F6 fine dust filer and passes through an automatic mechanical flow-rate controller that limits the fresh air to a set maximum. The air then passes through the energy-recovery unit, followed by a 4-pipe coil to further cool or heat it before being delivered to the space. Extract air passes through a coarse dust filter and then through the energy-recovery module. To enable free cooling to be provided using outside air, the energy-recovery unit can be bypassed. The units in Capricorn House can provide three flow rates — 60, 90 and 120 m3/h, and all three settings can operate on full recirculation or fresh air. Energy efficiency can be further increased by operating units in an asynchronous balanced mode. All dampers, including recirculation, are open. The exhaust-air fan can be controlled independently of the BMS to provide a constant flow and, depending on the speed of the supply fan, more or less air is recirculated, making possible substantial energy savings in heating and cooling modes than using full fresh air. UK potential Terry Farthing of Trox UK believes this approach to integrating the building façade and services has definite potential in the UK. He suggests its specification would be ideal not only for office complexes but also schools, hospitals and many other types ofFor more information on this story, click here:Jan 07, 68
