Brussels, 24 Nov 2005
Winter is not an easy time for residents of Rattenberg in the Austrian Tyrol. A nearby hill south of the city entirely blocks out the Sun from November to mid-February. But heliostat technology is about to put an end to the dark days and bring the sun back to inhabitants by 2007.
When Rattenberg was founded a thousand years ago, its location between the hill to the south and the Inn River to the north was ideal for protecting the population from intruders - security was valued more highly than sunshine at that time. Nowadays, however, people are not so keen to live without sunlight, and Rattenberg's population is steadily falling, due in part to the lack of winter sun.
With help from the pan-European EUREKA programme, Bartenbach Lichtlabor GmbH, an Austrian company pioneering the development products for day-lighting and artificial lighting, thinks it has worked out a solution based in heliostat technology. A heliostat is a movable mirror which tracks the sun as it crosses the sky, thus constantly reflecting direct sunlight to any desired location by means of other fixed mirrors.
The company has already used heliostats in previous lighting projects around the world, for example to bring sunshine into basements and railway stations. But due to the high engineering and installation costs involved, heliostats were thought to be suitable only for 'effect illumination'. Bartenbach LichtLabor feels now that the reflector technology is advanced enough to justify the company's first attempt to bring sunshine to an entire population.
In the Rattenberg project, the heliostats are to be located about 400 m north of the city, and their task is to re-direct sunlight towards secondary reflectors located on top of Castle Hill, just above the city. The heliostats rest on a ball joint and are controlled by a computer that automatically traces the movement of the sun.
According to project manager Markus Peskoller, this method will provide illumination with all the properties of natural sunlight - accentuated spots, sharp contrast between light and shadow, brilliant light, spectral colour resolutions, and sparkling effects. Sunlight will not be present throughout the entire city, but residents and visitors will be aware of sunshine at any location, and will therefore gain the important psychological impression of being in a sunny city.
Bartenbach LichtLabor began its feasibility study and detailed development plans at the beginning of 2005, but due to the complexity of the project, they say an extended design and development process is required before this concept can be implemented. The present engineering phase will last around 12 to 15 months.
The company plans to have a full-scale mock-up of individual components ready by early summer 2006. Before then, however, several challenges need to be overcome, not least financing of the full-scale project, the budget for which is expected to run to around 1.5 million euro.
Bartenbach Lichtlabor and the municipality of Rattenberg found financial support for the project through the EUREKA programme. The project includes the participation of a German company and an Italian university, and aims at developing technological components that will allow sunlight installations to solve the problems of urban regions suffering a prolonged deficit of sunlight. Rattenberg's dark winter fate is shared by another sixty villages in the Tyrol region alone, and other mountainous towns could be attracted by the success of the project.