Textile membranes
Lightweight and flexible envelopes as functional building membranes

The Allianz-Arena in Munich and the Water Cube in Beijing offer a spectacular demonstration of the new capabilities of textile architecture. In the EnOB research project “Development of low-emissivity coatings in textile architecture”, sheeting, fabrics and membrane constructions are provided with a special coating that makes a significant improvement to their thermal properties. These are referred to as low-e coatings, which emit little heat and reflect incoming thermal radiation well.

As part of a new research project “Membrane constructions for the energy-oriented refurbishment of buildings” (MESG), the aim is firstly to develop new concepts in order to achieve significant energy savings for buildings in Germany through the use of sheeting or fabrics in refurbishment projects. This involves heating energy as well as cooling and lighting energy. Secondly, such concepts can also contribute to energy optimisation in new buildings.

Membrane with integrated PV module © Jan Cremers / Hightex GmbH | Membrane with integrated PV module

In addition, an interdisciplinary approach is being pursued as part of the project. As well as the individual components, this will also look at their integration into the building and the control concept that is necessary for the heating and/or climate control system. For example, an increase in thermal mass with simultaneous reduction of the response time of the building’s control system is desirable in order to enable an optimum control strategy in respect of ventilation, heating and cooling.

Successes

To date, functional surface coatings have been developed that reduce heat emission into the environment. Low-e fabrics of this kind can significantly improve the thermal insulation of membrane constructions, thereby contributing to increasing energy efficiency in the building. At the same time it has become possible to combine the low-e characteristic with any desired colour effect, which yields flexible architectural design possibilities.

A further aim of the project is to prepare a pilot application and implement individual innovations and developments in connection with real buildings after the project ends. 

Application

The scientists developed a concept for an inner courtyard roof for two buildings at the HFT Stuttgart and the TU Munich. One focus of the research was the thermal flow conditions as well as the daylight situation in the atrium and the adjoining rooms. The results show that ventilation options must be provided via the membrane roof, as the interior temperatures in summer rise steadily with height. Cushions that can be moved upwards are an option here. Depending on the lifting height, a variable opening width is created. A sufficient number of adjustable air inlets ensures the necessary air exchange.

The daylight situation depends on the geometry and size of the covered courtyard. In the case of the HFT Stuttgart, the small and tube-like area of 400 m2 of roof surface means that the adjoining office rooms are no longer supplied with sufficient daylight from a room depth of 2 metres. In Munich, with a covered area of 1,300 m2, the offices have sufficient daylight.

The climate concept places high demands on the building services. The atrium behaves like an air collector. The air temperatures vary greatly depending on the air exchange and solar irradiation.