Just Burgeff architekten and a3lab
Asterios Agkathidis

Client: Aberdeen GmbH, Frankfurt am Main
Design: Just/Burgeff Architekten GmbH, Frankfurt am Main & a3lab, Asterios Agkathidis Architecture, Frankfurt am Main
Structural design: Wilhelm und Partner, Stuttgart
Date of completion: December, 2010
Location: Hamburger-Allee, Frankfurt am Main

WestendGate, also known as the Marriott Hotel, has currently being extensively modernized. At 159 meters and 47 storeys, the original structure was for a short time the tallest high-rise in Germany. Built in 1976 by the architects Siegfried Hoyer and Richard Heil in the Westend of Frankfurt am Main, the building became the path breaker for high-rise construction in the whole district and the rest of Frankfurt.
Among other things, the renovation includes an architectural and energy efficient new design as well as a new design and refurbishing of the entire façade, the installation of new solar façade modules, new building air-conditioning and optimizing of the lighting.

Grounds and Canopy
The high-rise is located at the intersection of public green areas which are now extended by the newly created grounds. With the relocation of the underground garage exit, a large urban space for recreation was established.
The organic tree-like structure of the sculptural roof is easily recognizable from a great distance. 1000 square meters of roof surface extend at one point up to a height of 14 meters, zoning in the square, with translucent air cushions filling out the construction and providing office workers and hotel guests refuge from the rain.

Idea and Determination of Form
The roof landscape design integrates aspects of urban development as well as spatial program and structural demands.
The flying reticulated shell, created from an inverted tree growth algorithm, is supported on the supports of the underground garage. The tree-like mesh was statically optimized with a Finite Element Analysis method to arrived at a minimal deployment of steel. The result was doubly curved surfaces, which depict the distribution of forces of the structural framework. A unity of form and structure.
This type of „associative“ design requires not only the deployment of highly developed software, but also a new form of collaboration between all those involved in the planning.

Execution
The supporting structure consists of steel pipes.
The double curved, hive-like roof surfaces were fitted with transparent pneumatic ETFE plastic cushions in different shapes. The permanently inflated cushions furnish protection against sun and rain in spite of their optical and physical airiness, offer an unencumbered view of the future new WestendGate façade.
The canopy draws in the entire forecourt, which provides access to the combined new office centre and hotel driveway ensemble.

Façade
The existing façade was completely renovated and redesigned and vertically arranged solar façade modules are integrated on the outside.
The façade was assembled from 3-dimensional components. As the shadow and the light reflections of the elements vary depending on the position of the sun, the façade adapts to the sunlight.