Making radio waves.

This building may, as the author suggests, represent an intermediate stage in the development of electronic communications. But it does very clearly exemplify today's balance between humanity and the world of machines.

As exchange of electronic information increases there is a growing need for microwave links - high-frequency radio waves transmitted in a straight line from one parabolic dish to another, via satellites or with repeater stations to overcome the earth's curvature. Until a few years ago, electronic communications in Lausanne converged on the turn-of-the-century central Post Office, but antennae all over the listed building were unacceptable, and the position was compromised for radio reception. Swiss Telecom therefore decided to build a new telecommunications station on the city outskirts. One might have expected that for maximum reach the building should be placed as high as possible on a hill or mountain top, but such exposure brings with it excessive interference.(1) The place chosen was Ecublens, a western suburb on Lake Geneva where the building commands a clear view of its most important link stations. Next door are Lausanne University and Ecole Polytechnique Federale, which occupies part of a floor of the new building with a research project. The new building is inevitably a landmark, and the position makes it a gatepost for city and both universities.

Rodolphe Luscher was appointed as architect in 1987, and the building was completed early in 1995.(2) Although much of the work was sophisticated engineering, somehow all the disparate technical concerns had to be brought together in clear relationships and given some kind of narrative structure - especially the architect's task. Luscher decided, for example, that the upper part of the tower should be in steel and that it should grow out of the concrete core, when engineering logic suggested a simpler all concrete tower. And it was Luscher who created the tense relationship between the central core and its contrasting flanks. It all makes sense technically, but makes more than technical sense. The central item of the brief was clearly the transmitting and receiving station, but the complex also needed to provide engineers' offices and a base for their technical equipment. Less directly functional, though no less significant, was the need to give the expensive but invisible activities a visible focus and in some measure to ritualise its operations.

The tall central tower carries the aerials. Its spine is a rigid concrete shaft growing out of the linear central core. This core, again of concrete, is aligned precisely north-south and contains services, ducts and central stair. To each side of it are framed and clad structures. The eastern one, with its curved glass wall is clearly the front; the entrance at its north-east corner leads to reception and cafeteria on the ground floor. Above this are three office floors, and at the top a special conference room with a terrace offering spectacular views of the lake. On the west side is a stack of technical spaces housing transmitting equipment. The cantilevered top floor with airport-tower windows is the operators' control room. In the basement are large diesel generators which turn on automatically if power fails. Their shiny exhaust tubes run up the south side of the tower with other services.

To the west of the tower is a large platform over basements. Along the southern edge set at 15 metre intervals are support structures and underground equipment rooms for three upward-facing satellite dishes, the largest aerials in the complex.

In its plan, the building picks up and responds to various aspects of the site. The precise north-south orientation of the concrete core accords with the rationalist grid of the polytechnic campus, but the territory west of the tower follows the building line against the main road, which is skewed some 23.5 degrees anti-clockwise of east-west. This angle twists the construction grid for both tower and car park area 4 degrees anti- clockwise from north-south, for reasons that are not at first obvious.(3)

Within the building, the 4-degree angle shift is the crucial agent of disengagement. Playing on the two themes of communication and transparency, it detaches the central core from the two flanking territories and produces corridors tapering in opposite directions on the two sides. On the east (office) side, corridors expand toward the south and lake, allowing the introduction of open wells which reveal the verticality of the building. On the west side, in contrast, corridors taper with reducing traffic, the single open well and best view being at the north end. So the angle shift in plan enlivens and differentiates the building's territories helping occupants to orientate themselves. In contrast, the continuous plate floors of conventional office towers allow no vertical views except through peripheral windows, and lifts anaesthetise almost all sense of vertical progression.

Also important to the general organisation and effect of the building are the two curves introduced into the plan. The large arc to the north contains the whole rear of the complex and defines the raised platform to the west. Following this curve, the gentle vehicle ramp onto the platform is neatly integrated. The other curve is taken by the glass wall of the offices. It allows expansion towards spectacular views, and from the outside it stresses the corner position of the building between main road and university drive. The curve contrasts, too, with the straight facade of the technical rooms to west, just as its elaborate glazing system contrasts with their rudimentary cladding and clerestory strips.

Communications must be preserved at all times. Antennae have to be stable to remain accurately focused on distant companions. This required pile foundations some 30 metres deep, and extra-heavy steel work on the upper part of the tower, not for load-bearing but rigidity, preventing significant deflection even with winds of 100 mph. Such a mast inevitably acts as a giant lightning-conductor, and care had to be taken fully to earth all metal parts. The reinforcement in the concrete spine was welded together to make it act as a Faraday cage, preventing contamination of small signals by stray electric fields.(4)

The architects developed a sophisticated environmental strategy. Heat is extracted from the water in Switzerland's largest lake by heat pumps, and distributed through ceiling radiators. Summer cooling can be effected by reversing the process, but the primary instrument on the office side is a double glass wall with a wide ventilated cavity. By manipulating louvres in the outer glass skin, the stack effect in the three-storey cavity can be controlled, allowing cooling by convection. Inner wall windows can be opened at will.

As in earlier Luscher buildings, construction is on show and detailing fastidious. Habitual tricks with glass floors and balustrades are effortlessly incorporated, and raw concrete is surprisingly well finished, contrasting well with the more refined materials. A limited palette with some strong reds and blues adds cheer and a welcome touch of abstraction.

The station is an exciting place to visit, especially the open metal grids of the vertiginous upper platforms. It is now doubtful whether it will all be fully exploited, for in the eight year planning and construction period electronic equipment has become much more compact. So antennae on the tower are of much smaller diameter than originally envisaged, making the supporting structure seem inappropriately beefy.

It may not be long before the technology can perform without a special building. The exploitation of large antennae as signs, which has fascinated architects since the Constructivists, may become an anachronism. For the moment, though, the technical demands that make this building such an exciting landmark are genuine, and fulfilling them makes electronic communication both visible and susceptible to celebration.

1 For this and later technical information, see the article A Ecublens, "Telecom PTT construit le futur' by Andre Jacques, Journal de la Construction no 3, 15 March 1994.

2 For earlier works by Luscher see AR September 1991, pp48-51. 'Kindergarten contrasts', for Centre Enfantine in Lausanne.

3 Its basis lies in the rectangular grid of the car park area, which has the simple ratio of five to 15 metres. Since this 1:3 ratio occurs between the short side of the triangle and its hypotenuse, it produces the apparently irrational angle shift of 19.47 degrees, along with the discrepancy of around 4 degrees in relation to north-south.

4 See Jacques, above.