Prof. (Dr.) Dharmakanta
Kumbhakar
(drkdharmakanta1@gmail.com)
Lighting, or illumination, is the deliberate use of light to achieve a practical or aesthetic effect. Lighting includes the use of both natural illumination by capturing daylight as well as artificial light sources like lamps and light fixtures. Not only will greater reliance on natural light reduce energy consumption, but it will also favourably impact human health and performance. Daylighting has been proven to have positive effects on patients in hospitals as well as work and school performance. New studies have shown that the performance of students is influenced by the time and duration of daylight in their regular schedules.
Good lighting is essential for vision. If the lighting conditions are not ideal, the visual apparatus is put under strain, which may lead to general fatigue and a loss of efficiency. For efficient vision, the lighting should be sufficient to enable the eye to discern the details of the object as well as its surroundings. Well-designed lighting sends light only where it is needed without scattering it elsewhere. The eye responds to a range of illumination ranging from 0.1 lux (full moonlight night) to 100,000 lux (bright sunshine). There is considerable confusion about standards of illumination because of the adaptability of the eye. A useful rule of thumb is that the illumination level should be 30 times higher than the level at which the task can be done. Generally, visual efficiency increases with an increase in illumination, but the curve flattens out at higher levels when applying the law of diminishing return. The distribution of light should be uniform, having the same intensity over the whole field of work. If there are contrast differences in light, it will strain the eyes and adversely affect the visual acuity. Proper dispersal of light without the production of shadows is therefore necessary for efficient vision. Glare is excessive contrast. Glare causes annoyance. The eye cannot tolerate glare because it causes acute discomfort and reduces critical vision. Slight shadows are inevitable, but sharp and contrasting shadows are disturbing. The source of light should be constant. It should not flicker because flickering causes eye strain and may lead to accidents. The colour of the light is not very important as long as the intensity is adequate. A high level of illumination is required where there is little colour contrast.
Considerable attention has recently been focused on the biological effects of light. The observation that light could cause the in vitro degradation of bilirubin is now being used as a therapeutic measure (phototherapy) in premature infants with hyperbilirubinemia. Other biological effects of light include an effect on the biological rhythm of body temperature, physical activity, the stimulation of melanin synthesis, the activation of precursors of vitamin D, adrenocortical secretion, and food consumption.
Studies show that the quality of light affects people in many different ways. For example, office worker satisfaction and productivity can be positively affected by well-designed illumination. Building owners and managers have the potential to add value, reduce costs, and enhance performance through the application of good lighting. It’s no secret that people are attracted to well-lit public facilities, commercial shopping districts, and parks. Good lighting enhances the mood and desirability of these spaces. It contributes greatly to people’s sense of well-being. Lighting illuminates the performers and artists in a live theatre, dance, or musical performance and is selected and arranged to create dramatic effects. Correct light intensity and colour spectrum used in critical inspection or colour matching tasks, or for retail displays of food and clothing, give the best overall lighting effect.
Proper lighting can enhance task performance, improve the appearance of an area, or have positive psychological effects on occupants. Good lighting makes the home feel spacious, clean, and well-coming. Bad lighting causes headaches, sore eyes, and frustration in the kitchen at not being able to see what we are doing. However, emotions are intensified in the bright light. Designing school facilities to incorporate the right types of light at the right time of day for the right duration may improve student performance and well-being.
Light pollution is a growing problem in reaction to excess light being given off by numerous signs, houses, and buildings. Light pollution is described as artificial light that is excessive or intrudes where it is not wanted. Polluting light is often wasted light, involving unnecessary energy costs and carbon dioxide emissions. The adverse health effects, such as headache frequency, stress, and increased blood pressure, may be induced by the higher lighting levels. In addition, glare or excess light can decrease worker efficiency. Poorly designed lighting can compromise safety.