Demonstration of energy–efficient building
The new ZAE building located in the conversion area of the former Leighton Barracks in Würzburg, is scheduled for completion by the end of 2012. This whole area, which is also adjacent to the campus of the University of Würzburg, will be redeveloped completely in the course of the next few years, and turned into a new urban district called Hubland. University institutes, university-related services, as well as commercial and residential units are intended to supplement each other in an attractive mixture on the grounds.
The long, rectangular two–storey building designed by Lang Hugger Rampp provides office space, labs and technical centre rooms, as well as a seminar room on a floor area of 3,400 m². A public area with a hands–on information centre, presenting current research results and newly developed energy technologies – including those used in the new building itself – will be located on the ground floor. Easy-to-understand details about the energy consumptions and gains of the building will furthermore be presented in this information area.
The new building makes use of numerous efficiency technologies, both in the construction of the building itself and the technology of the facilities of the building. Some of these are still in the prototype phase and some — although already technically mature — are only used relatively rarely in buildings.
The most distinctive elements of the building envelope are certainly the convex roof membranes spanning the building. The membrane merely forms the outer envelope of a multiple–shell roof construction; the inner roof is flat, thermally insulated and only partly translucent. While the membrane functions as a light diffuser, offering protection from the weather as well as creating a thermally insulating layer of air between the two roof levels, the inner roof forms the actual climate envelope.
The façades of the ZAE Bayern building will be fitted with a newly developed, highly insulated profile system made of polyurethane, with a Uf value of 0.7 W/m²K, offering even better insulation than previously available profile systems for passive houses. TopTherm 90 — as the system is called — is moreover ready for installation of vacuum insulation glazing that has been developed at the ZAE for some years.
The interior finishing work of the new research building was carried out with dry construction techniques for the sake of flexibility. This means a limitation in the thermal mass and therefore also the heat storage capacity of the construction, which is to be compensated by integration of latent heat storage systems (PCM) in several locations of the construction. Installation of a newly developed heating and cooling ceiling with PCM layer in the upper storey office rooms is also planned. Connection of the PCM to an active cooling system was opted for to safeguard nightly discharge of the latent heat storage devices in midsummer as well.
The main source of thermal energy used by the new construction is local district heating. Installation of a solar heating system intended to satisfy most of the demand for hot water is further intended. The premises will be heated using three different systems. The heating and cooling ceilings with PCM already referred to will be installed in the offices and meeting rooms, an underfloor heating system will heat the foyer and information centre, and conventional radiators will be used in all the other rooms.
The building will be cooled using night–time infrared cooling as well as conventional vapour–compression refrigeration systems. The infrared cooling system is mainly intended to support the thermal discharge of the PCM cooling ceilings at night. The heat dissipated by these is initially transferred to a rain water cistern via a heat exchanger. At night, the water is pumped to the roof of the building for recooling, where it gives off heat (mainly by radiation) to the cold night sky while draining. The cooled off water is then returned to the cistern via rain drains and a filter.
Bavarian Center for Applied Energy Research (Bayerisches Zentrum für Angewandte Energieforschung e.V., ZAE Bayern), Würzburg, Germany
Lang Hugger Rampp GmbH, Munich, Germany
Building services engineering:
Ebert-Ingenieure GmbH, Munich, Germany
Support structure planning and project management:
SSF Ingenieure AG, Munich, Germany