Switchable facades and visual comfort

A. D. Tenner, Philips Lighting B.V., The Netherlands
L. Zonneveldt, TNO Building and Construction Research, The Netherlands

Keywords

light, daylight, electrochromic glazing, electric lighting, electric lighting control, daylight control, switchable facades, visual comfort, experimental research, user assessments, integrated lighting control

Abstract

Electrochromic glazing has been developed as an adaptable shading device for thermal energy control. This material has also a great potential in daylight and glare control. This paper discusses an experimental investigation of the possibility to provide high comfort and efficient lighting using electrochromic glazing. The integration of artificial lighting and daylight in working environments is a crucial factor [1].

In an experimental office separately controllable electrochromic windows have been installed in the façade to enable optimal daylight and glare control. The daylight is supplemented by electric lighting with suitable level and colour temperature, according to the transmittance (setting) of the glazing. People will be asked to work for several hours in the experimental office and will be questioned about their preferred lighting conditions and well-being.

The application of electrochromic glazing in this project is based on visual comfort criteria, multiple elements are used to enable maximal flexibility. An integrated system for the control of daylight and electric lighting based on lighting levels, glare prevention and colour temperature is developed through the use of LON network technology. Detailed monitoring (based on the IEA task 21 Monitoring Protocol [2]) involves all technical parameters mentioned above and will especially focus on user reactions.

This project is an ongoing research project and part of the European SWIFT project.

Preliminary results show that the electrochromic glazing is highly appreciated by the users. It is appreciated because it produces good, maybe a bit optimistic, rendering of the outside world and meanwhile reasonable glare protection. Also daylight measurements show good control for the daylight distribution in the rooms.