The Gerontology Technology Centre in Bad Tolz, Germany is the first building to use a single layer of transparent ETFE film for its curved facade. The spiral-shaped building houses the Innovations Centre and the Generation Research Program Institute, forming the nucleus that new ideas will radiate from. An open walkway behind the double curved ETFE facade acts as a climate buffer and reduces heating requirements through solar heat gain in winter. The complex curved geometry of the facade was constructed using a steel frame and tensioned ETFE film, with adjustments made based on laser scans and without pre-construction drawings.

1. NANDINI S DEV
IRENE ANN TOMI
LOCATION : BAD TOLZ GERMANY
COMPLETED YEAR : 2004
MATERIAL : ETFE FILM, TRANSPARENT ONE LAYER
FACADE TYPE : SINGLE LEAF, MECHANICALLY PRETENSIONED
USE : RESEARCH/ CIRCULATION
GERONTOLOGY TECHNOLOGY
CENTRE, BAD TÖLZ

2. The Gerontology Technology Centre [GTZ) in Bad Tolz is the first building in the world to use a single
layer of transparent film for its facade. It is not only the physical properties of this extremely thin
material that make this a highly unusual facade design; the double curvature of the facade lends the
building a new aesthetic and presents a challenge to conventional perceptions of architecture.
CONCEPT
To create a focal point for and at the same time also a contrast to the rigid, box-like arrangement of the
former American army barracks, the architects designed a spiral-shaped building to house the new
Innovations Centre. The spiral can be seen as a symbol of renewal, of development, or as a symbol of life
itself, reflecting the work of the centre. For this purpose, the GRP [Generation Research Program)
Institute, an Off-campus section of Munich's Ludwig Maximilian University, was housed in the centre of the
spiral, forming in terms of both content and location the nucleus from where new impulses will radiate.
This geometrically complex building evolves like a ramp from the three storeys at the start of the spiral to
the four storeys at the end of the spiral. In addition, behind the facade each storey is stepped back and
includes an open walkway at each level. The walkways link the individual office retail units, thus
encouraging informal communication between the various companies.
CLIMATE CONCEPT
The external envelope in front of these open walkways is formed by a transparent ETFE film curving in two
directions. It provides protection against the weather and at the same time controls the internal climate.
The open access zone behind, acting as a kind of conservatory, forms a climate buffer between the
building itself and the exterior. In winter, spring and autumn , the intermediate zone stores the solar
radiation and therefore reduces the heating requirements and hence the heating costs. The stack effect in
the multi storey void between walkways and facade is responsible for the airflow which replaces the warm
interior air with cold night air. Another advantage is the generous transparency of the facade ; daylight
can be exploited to the full and energy costs for artificial lighting minimised.

3. CONSTRUCTION
● The curve of the membrane facade gives it a natural look, like a row of
bird feathers .
● The single layer of ETFE film forms a complex, twisted surface geometry
due to the spiral-shaped, terraced and, at the same time , ramp -like
arrangement of the building.
● Consequently, the load bearing structure over which the film is stretched
is not simply a supporting framework, but rather determines the very
shape of the facade .
● The architects chose steel Circular hollow sections for the facade
structure. Inclined in two directions, they form trapezoidal bays on
elevation and in section follow the terrace-like outline of the building.
● Owing to the ramp -like increase in height, every column is positioned at
a different angle to the building. In addition, every trapezoidal bay
includes a diagonal member which curves outwards.

4. ● Only after erecting the load bearing structure and with the help of
special computer programs was it possible to draw the actual
double-curvature membrane geometry and hence the elevation.
● A three -dimensional laser survey of the most important fixed points
provided the necessary input data for this. The drawings were first
produced after erection and served only for the computer-aided
determination of the facade material. This meant that there were no
drawings, as design aids, with which to check, fine-tune and adjust the
configuration. The laws of statics and physics replaced the drawings.
● Another special feature of the construction results from the relaxation
angle of the film. Unknown in conventional membrane construction , the
tensioning facility necessary was devised in empirical trials on a 1:1
model - a world first. Finally, the circular aluminium bars with
adjustable screws responsible for the final tension in the film were
mounted on the curved diagonal members.
FABRICATION