Discovery of fire and subsequently lighting has contributed hugely to the modern advancements in human life all over the world. However, only a few are aware of proper applications of lighting or that effective lighting also needs planning and design. Most people incorrectly infer lighting design to mean simply selecting lighting equipment for a system. Of course, selecting the most energy-efficient and cost-effective products is important, but they are simply the tools to achieve the design.

In reality, lighting design requires assessing and meeting the needs of the people who will use the space. It also requires skillful balancing between the functional aspects and the aesthetic impact of the lighting system.

That makes lighting both an art and a science. It also implies there cannot be any hard and fast rules for designing lighting systems. Additionally, there will also not be any single ideal solution optimum for all lighting problems. Typically, lighting designers face conflicting requirements and must set priorities before reaching a satisfactory compromise. Assets necessary for successful lighting designers include a proper understanding of basic lighting concepts, extensive experience, careful planning, assessment and analysis.

Lighting mostly involves use of energy. One of the chief concerns is achieving optimum energy efficiency, which means getting maximum lighting quality with minimum consumption of energy. This requires a combination of thoughtful design together with selecting the appropriate lamp, luminaire and control system. Additionally, decisions made must include informed choices of the level of illumination required, the integration and awareness of the space or environment being lit.

Lighting designers must have an intimate knowledge of the human eye and the way it perceives light and color. For example, light falling on an object is partly absorbed and partly reflected by the object. We see the object because of the reflected light entering our eye. The color of the reflected light also determines the perceived color of the object.

A flexible lens within the eye helps to focus the image on the retina and allows clear vision. The retina of the eye has many rods and cones. These convert light into electrical impulses that reach the brain via the optic nerve. The brain interprets the impulses into a proper image. However, illumination levels also change the way the eye perceives an object.

During the day and in normal daylight conditions, the cones in the retina enable us to see details in color. This is photopic or daytime adaption of the eye. As light levels dip, cones become less effective and the more sensitive rods take over. For example, in a well-lit street, the eye sees a mixture of cones and rods to see.

However, rods do not differentiate colors and respond only to different shades of black and white. The overall impression in average lighting is an image with lower color – the mesopic adaption. As light levels fall even further, such as in dim moonlight, the cones cease to function altogether and the eye loses all capability to see in color. This gives completely black and white vision – the scotopic or nighttime adaption.