Millions of people spend a significant part of their lives working. Electric lighting is provided at their workplaces to ensure that they can see to do their work quickly, accurately and easily. Thus, the provision of lighting has an economic impact beyond the cost of equipment, installation and power. Further, in many countries, the cost of providing the lighting at a work place is miniscule relative to other costs. For example, in the United States, the annual cost of lighting a 10 m2 office is typically less than 0.1% of the cost of paying someone to occupy that office (New Buildings Institute, 2010).