Light(s) at Wuhan station
A tool like Phanie was absolutely necessary for photo-simulation of the entire station with its 4 600 planned light fittings with four direct and indirect lighting levels in the 40-meter high all-curved architecture. This powerful software was developed by CSTB engineers and it has the undeniable advantage of being regularly updated. As soon as a particular or complex situation arises, a computer scientist enriches the software core with new modules. For example, the new materials are measured in the laboratory to determine their photometric characteristics before being immediately integrated into the software databank.
For the Wuhan project, CSTB team began by simplifying the 3D model supplied by AREP. The number of facets in the station’s curved architectures has been reduced and all elements that do not influence the light environment were eliminated so as to reduce the calculation time. Data on the behavior of materials in terms of absorption, transmission or reflection have been integrated. Level by level, the different types of light fittings and their photometric characteristics were positioned in space and oriented according to the initial assumptions. A long, iterative refining work on the number and distribution of light sources was then used to validate the systems as a function of the uniformity and intensity of the required lighting. No less than 12 hours of calculation were involved between each model verification step!
Studies integrating indirect light sources and sources of light reflected by the roof have shown that some light fittings, specially manufactured for the operation, need to be installed in pairs at a height of 4.50 m and a spacing of 18 meters, so as to obtain an average illumination of the platforms equal to 80 lux. The lighting project is exceptional in its size, its interest and its design complexity, and it is also particularly luxurious in terms of the power used. "With some areas illuminated to more than 200 lux in the car parks, as requested by the Wuhan owner, we are globally well above currently accepted European values", says Michel Garcia, engineer at CSTB. An outstanding cultural feature, even a genuinely local landmark, although not altogether consistent with French energy concerns.
