Daylight Responsive Systems Research Articles

Modern Mashrabiyas with High-tech Daylight Responsive Systems

The environmental and social role of closed oriental balconies (Mashrabiyas) remains a significant vernacular aspect of Middle Eastern architecture. However, nowadays this traditional Islamic window element with its characteristic latticework is used to cover entire buildings as an oriental ornament, providing local identity and a sun-shading device for cooling. In fact, designers have reinvented this vernacular Islamic wooden structure into high-tech responsive daylight systems – often on a massive scale and using computer technology – not only to cover tall buildings as an oriental ornament, but also as a major responsive daylight system.It is possible to use the traditional architectural Islamic elements of the Middle East for problem solving design solutions in present-day architecture. The potential for achieving these solutions lies in the effective combination of the design concepts of the traditional elements with new smart materials and technologies. Hence, modern mashrabiyas could be a major responsive daylight system. Contextual information drawn from relevant theory, ethnography and practice is used to form a methodological framework for the modern mashrabiyas with high-tech responsive daylight systems. The main results set boundaries for the viability of computer technology to produce mashrabiyas and promote a sustainable way of reviving their use within Middle Eastern buildings.

The role of spectral response of photosensors in daylight responsive systems

Lighting control technologies using photosensors have a great potential for energy savings in areas with high levels of daylight. Although the proper application of these controls can exploit this potential, unfortunately, it has been accomplished in a small percentage of new projects. One reason is the difficulty in justification of energy savings, which in turn, is directly linked with the simulation of the behaviour of these lighting controls. The core of these systems is the photosensor, which adjusts the electric light output in proportion to the amount of the daylight that detects, using its spatial and spectral response. The aim of this study is to quantify the impact of photosensor spectral response on its illuminance values, by taking into account various daylight spectra as these are modified due to various types of coloured glazing. Five commercial photosensors were selected and their spectral response was measured. In addition, spectral transmittance of 16 commercial types of glazing was measured as well. Using these data, a set of simulations were performed using three colour channels in a typical office room and the relative differences in illuminance – and thus energy savings – among the photosensors are presented. The results show that differences are significant ranging from 36 to 118%, a fact that can affect the estimated payback period of a lighting control system.

Quantifying energy savings in daylight responsive systems: The role of dimming electronic ballasts

The application of lighting control technologies with photosensors has led to an increase in public interest. Although these technologies have been promoted during the last years their successful use in buildings has been accomplished in a small percentage of new projects. One reason is the difficulty in quantifying the energy savings and thus the subsequent payback period. Daylight responsive dimming systems consist of three basic components: photosensor, controller, and dimming unit. Electronic dimming ballast (EDB) is one substantial component of these lighting control systems which can adjust the light output due to the transferred signal from the photosensor and lighting controller. The aim of this study is to quantify energy savings among different EDBs. Eighteen commercial EDBs were selected and various sets of electrical and illuminance measurements were taken for different dimming levels, in order to develop polynomial functions between light output and consumed power. Using the measured data, a set of simulations were performed for a photosensor with an ideal cosine spatial sensitivity distribution installed in a typical office room using two control algorithms, closed loop and integral reset, trying to quantify the relative differences in energy savings.