A global method for efficient synchronized shading control using the 'effective daylight' concept

摘要

The majority of modern office buildings have large glass facades on every orientation. The significant impact of glass facades and dynamic controls on energy use for lighting and air-conditioning should be carefully investigated to determine ways of saving energy while maintaining comfortable conditions for the occupants. Interior roller shades are commonly used to control glare and solar heat gain. Reduced outdoor view, glare problems, increased energy use or insufficient daylight provision are some of the problems encountered with simple shading controls. Automated control of roller shades may result in improved conditions and reduced energy use if advanced criteria are used, but recent studies have shown that appropriate set points are not easy to calculate and apply in practice. This paper extends previous findings and presents the development of a new, improved control strategy applicable for any climate and orientation. The new control method, based on the "effective daylight" transmitted into the space, aims to maximize daylight utilization while satisfying visual comfort restrictions using only one sensor mounted on the window. It can be applied to spaces with one or multiple exterior facades equipped with roller shades. The method was implemented in full-scale offices and experimental results are presented in terms of daylighting and visual comfort performance. Furthermore, the new strategy was implemented in an integrated thermal and daylighting model, validated by experimental data, to investigate the annual energy and daylighting performance of perimeter spaces with one or multiple exterior facades, and compare the new control strategy with more conventional shading controls. Overall, this study presents the principle of synchronized control of multiple shading devices on different facades (orientations) of commercial buildings. Integrated with efficient lighting and HVAC controls, it can lead to significant improvement of indoor conditions and reduced energy use.