Daylight in underground (exposition) spaces

Truus de Bruin-Hordijk, Siuhang Chan and Marinus van der Voorden Building Physics Group, Faculty of Architecture, Delft University of Technology P. O. Box 5043, 2600 GA Delft, The Netherlands E-mail: G. J.de Bruin-Hordijk@bk. tudelft. nl

The world population is still growing and people will always need more space for living. Problems arise especially in the urban environment. One of the possibilities to solve the problems is to make constructions and buildings below the earth’ s surface. However, underground spaces give many people negative associations with cold, dampness and most of all darkness. It feels gloomy and unsafe. People need light, natural light where possible, and they like to be connected with their surroundings.

Daylight is dynamic and gives information about the weather and the time. The possibilities for the use of daylight in underground spaces has been investigated.

1. THE SCOPE OF THIS PAPER

In order to investigate the possibilities for the use of daylight in underground spaces we have limited our study to one underground space with only one light entrance, a tube in the ceiling, to measure the level of illuminance for different dimensions of the space and the tube. One light entrance for one space was a precondition made beforehand, because it is the most simple model and one light entrance above earth surface can be easily integrated into the surroundings or can be hidden by landscaping.

First, preliminary experiments in the daylight chamber of our faculty were done.

After that, a simulation model of an underground exposition space is made with the computer program (desktop) Radiance [1]. Computer simulations with a diffuse sky and a clear sky are done. After the first conclusions, different variants for the light entrance are simulated in Radiance in order to avoid the negative effects of the direct sunlight. At the end of this paper a design concept for the light entrance is shown.