Introduction

Daylighting systems by Ahmet Cakir

Harvesting daylight with sophisticated modern means, opening our buildings to natural light in different ways or simple fenestration strategies require simple to complex technologies. Since daylight use is always accompanied by additional energy input into buildings efficient means for controlling energy input are always part of daylighting systems. This forum is for presenting and discussing high- and low-tech daylighting systems, their possible benefits and the prospects of daylighting for the next 50 years. A number of different benefits of daylighting is being discussed, among them: 1. Reduce daytime electric lighting costs by up to 90% annually. 2. Reduce lighting maintenance costs by up to 50% annually. 3. Reduce electric lighting heat loads on air conditioning systems. 4. Create an attractive and comfortable work environment 5. Reduce eyestrain and fatigue from artificial lighting 6. Increase light levels without the glare caused by other lighting systems. 7. Ensure that colors remain true, vivid, and vibrant. 8. Reduce waste from electric generation and transport. Some of these benefits are based on cost of energy. If the motivation for using daylight is based on cost related factors the effects of a system can easily be calculated. Reducing daytime electric costs by up to 90% can be a realistic estimate for many buildings up to a latitude of 50° N or S. Also estimable are effects concerning the heat loads on air conditioning systems which are not necessarily positive. However, improved motivation for workers by reduced eyestrain or by a more appealing environment is not calculable in monetary terms. But such effects may overweigh all other benefits of daylighting even in monetary terms by improved efficiency of work.