Introduction

Energy aspects of lighting are increasingly drawing attention. In the early seventies much attention was focused on energy saving through the development and use of energy efficient lamps. This lead for instance to large scale production and implementation of highly efficient High Frequency lighting appliances such as the new generation of CFLs.The quality of luminaires and additional electronics such as controls did not stay behind. On the contrary, recent years have seen the introduction of smart control devices and highly efficient electronic ballasts whereas a complete turn around occurred in the design of luminaires. Over the last decades installed power for office rooms has dropped even further as a result of lower depreciation rates of lamps and luminaires.

Over the last few years, also a renewed interest in the utilisation of daylight is apparent. Daylight can provide excellent lighting in many buildings. Using daylight as a source for task lighting however asks for special care for daylight as a light source is constantly varying. So when not enough daylight is available, or when parts of the room remote from a window are in question, electric light has to be supplemented

While artificial lighting can be very efficient, problems arise when daylight and electric light are combined. These problems are well known and are getting a lot of attention. Thanks to powerful new design tools that have come available new approaches can be made. In many countries the use of daylight in working spaces is compulsory. Hence windows have to be provided that not only offer a view on the outside world but that can also provide task illumination with daylight. By using as much daylight as possible electric energy for lighting can be saved.

One of the most important conclusions regarding energy efficient lighting in general that was again confirmed during this 23rd session of the CIE in Delhi, is that quality and energy efficiency of lighting are very much related. It is important to note that without good quality in lighting no real energy savings can be made. Therefore we first summarise some of the conclusions with respect to the important item of quality made in the papers presented at the Session.

For research into quality aspects of lighting extended knowledge of biological and psychological factors is required. Some interesting new results were shown in New Delhi. These results indicate possible new approaches and solutions, but also constraints expected to be encountered.

From there we move on to new developments in energy efficient lighting products (components and systems) and further to energy efficient lighting design and usage. Some highly sophisticated design tools and techniques for improving the energy efficiency of lighting products, unveiled in New Delhi, are highlighted.

In two highly interesting and comprehensive descriptions of the actual lighting situation in developing countries the discerning reader will find openings for extending liaisons and possible future co-operation. Examples of successful implementation of energy efficient lighting and the refurbishment of existing installations with energy saving technology presented at the 23rd session of the CIE in New Delhi are given.

We will conclude this review of the 23rd session of the CIE with the summary of Evan Mills (LBL/USA) on the results of his workshop on energy efficient lighting.