Light, lightness and transparency
From the outset creating an atmosphere that blends light, lightness and transparency was a prime concern for Renzo Piano. At the same time the illumination inside the exhibition areas has to be precisely regulated so that the quality and life of the highly light-sensitive works of art are not put at risk.

Restorers recommended a luminous intensity of only 50 to 100 lux (unit of illumination) for the works of Paul Klee. To give some idea of what this means, a sunny day in July produces a luminous intensity of 100,000 lux while a cloudy day in March has a brightness of some 10,000 lux. It takes 400 lux to illuminate an office with electric lighting, and even the Moon’s crescent produces an illumination of 0.2 lux.

Crepuscular twilight mood
The intricate light and luminous ceiling used at the Fondation Beyeler, also designed by Renzo Piano, makes sense as the collection is able to withstand an illumination of 240 lux without damage. Compared to those levels of brightness the exhibition areas of the Zentrum Paul Klee feature a crepuscular twilight mood. Here projectors are used to provide the basic lighting by casting the light onto the ceiling from where it is reflected with a softer, broader effect. With the precision-control lighting system additional light sources can be used to showcase individual works of art, creating the ideal, consistent conditions for admiring the works on display.