Lighting Energy Conservation Research Articles

Maximum photosynthetic efficiency: A problem to be resolved

The great disarray in the measurements of the maximum efficiency of conservation of light energy in photosynthesis is an outstanding problem in the development of photosynthetic biotechnology. The short-term measurements of the efficiency based on O(2) release by suspensions of cells or chloroplasts have given minimum quantum demands between 4 and 12 hv/O(2). The defect of the short term measurements is that the effects of growth conditions, which can alter the efficiency by a factor of 2, have been generally ignored. In contrast, the steady-state growth method, which depends on measurement of the maximum growth yield in photosynthesis, ensures that growth and photosynthesis are normally coupled. This growth method indicates that the minimum quantum demand lies in the relatively narrow range of 5.3 to 8.6 hv/O(2). The question of whether the minimum quantum demand is less or greater than 8 hv/O(2) is a crucial test for present theoretical concepts of the conversion of radiant energy to chemical energy in photosynthesis. To obtain the definitive maximum value more rigorously controlled measurements of photosynthetic efficiency in growing organisms are essential.

Lighting energy conservation: simple analytic methods with time-lapse photography

Although time-lapse photography offers great potential for providing information on lighting energy conservation, it has been undeveloped because the quantity and detail of the data demand a great deal of time for analysis. Two simple analytic procedures are described to make time-lapse photography more useful: (1) a sampling procedure for data reduction, and (2) a formula for computing wasted lighting energy based upon occupancy and light usage. It is argued that poor utilisation of lighting energy can be addressed with these procedures.

Lighting Controls, Patterns of Lighting Consumption, and Energy Conservation

Some of the important areas of the lighting energy conservation research program currently being carried out at the Division of Building Research, National Research Council of Canada, are described. The major emphasis of the program is to monitor present patterns and levels of lighting consumption in offices and schools and then develop and encourage cost-effective control systems to reduce the hours of use of lighting power loads. A new device to measure lighting energy consumption is described. Tine-lapse photography is being employed to obtain detailed information regarding patterns of lighting use in offices and schools. This information is used to develop cost-effective manual- and automatic- control devices. The savings measured with a daylight-linked automatic system installed in a typical office are discussed.

Procedure to Determine Background Luminance for use inESIand Visual Performance Methods

Two major factors determine the visibility of common objects: the luminance contrast of the object detail with respect to its immediate background and the adaptation level of the visual system. CIE Publication No. 19 chooses the term task luminance to characterize an observer's state of adaptation and then uses this factor to describe a task in connection with all operations carried out in the visual performance framework of methods. The imprecision and poor understanding of this parameter severely restrict the accuracy of the visual performance methodology in lighting energy conservation and design. Experimental procedures are proposed for accurate measurement of background luminance for typical office and school tasks.

The CIE visual performance system

The International Commission on Illumination (CIE) has developed a system for evaluating the visual performance aspects of lighting. The system and its concepts are presented with special reference to lighting energy conservation. Some of the problems involved in the application of the CIE system and the data required before widespread application is possible are discussed.

Lighting Esthetics with Energy Saving Ideas

Lighting engineers' best contribution to the energy conservation movement will be to optimize the application of new and highly efficient lighting sources in an esthetic way. In order to achieve this goal, creativity is the key. This could bring lighting esthetics and energy conservation into coexistence. This paper outlines some creative lighting systems which use highly efficient light sources to achieve energy conservation as well as esthetic appearances.