Light is ubiquitous. Therefore, we often take light for granted and give little thought to its value. This will change as the world population expands exponentially and we strive for a more sustainable planet. Commodities like light, air, water, and nutrition will begin to take on increased significance and will begin to be seen as more valuable.
But how does one measure the value of light? Value is calculated as a ratio of the benefits provided by a desired product or service divided by the costs to procure that product or service. To calculate the value of light then, we first have to decide on the purpose of the lighting. Will it be used to thread a needle, complete a jigsaw puzzle, avoid objects in the roadway, detect deer coming onto the highway, illuminate a photograph on the wall, or even to sleep well? Once we decide on the purpose (i.e., define the desired benefit), we then need to accurately measure that benefit as well as the costs needed to deliver that benefit.
Unless we have expectations, it is very hard to meet them. Surprisingly perhaps, we often do not fully understand what lighting can do for us. We know that we need lighting, but often that is as far as the thinking goes. We know that lighting is installed in and on every building, motor vehicle, airplane, and on most roadways and streets. We accept and we copy what has been done before, even if we do not fully understand or measure the benefits that lighting provides in those situations. We do a really good job, however, of conceptualizing the costs of those lighting systems because we can readily measure those costs. We precisely measure the price of the light source, the fixture, its installation, the costs of maintenance, and the amount of electricity needed to energize the source. Whether we do simple payback calculations or life-cycle cost analyses, we have a firm grasp on how much lighting systems cost.
Online access to SPIE eBooks is limited to subscribing institutions.