Artificial lighting consumes a significant part of all electrical energy consumed worldwide. In homes and offices from 20 to 50 percent of total energy consumed is due to lighting. Most importantly, for some buildings over 90 percent of lighting energy consumed can be an unnecessary expense through over-illumination.
The cost of that lighting can be substantial. A single 100 W light bulb used just 6 hours a day can cost over $25 per year to use (.12/kWh). Thus lighting represents a critical component of energy use today, especially in large office buildings where there are many alternatives for energy usage in lighting. There are several strategies available to minimize energy requirements in any building:
* Specification of illumination requirements for each given use area.
* Analysis of lighting quality to ensure that adverse components of lighting (for example, glare or incorrect color spectrum) are not biasing the design.
* Integration of space planning and interior architecture (including choice of interior surfaces and room geometries) to lighting design.
* Design of time of day use that does not expend unnecessary energy.
* Selection of fixture and lamp types that reflect best available technology for energy conservation.
* Training of building occupants to use lighting equipment in most efficient manner.
* Maintenance of lighting systems to minimize energy wastage.
* Use of natural light - some big box stores are being built (ca 2006 on) with numerous plastic bubble skylights, in many cases completely obviating the need for interior artificial lighting for many hours of the day.