Lighting systems in offices account for around 30 to 40% of the building's energy consumption, so anything that can be done to reduce the load is of benefit. Luckily, the latest technology can help save bills.
There are obvious things that have been done for decades that will save energy such as motion control lighting zones and low power light bulb but now, designers are coming up with more advanced systems.
Daylight harvesting or day lighting is the "use of daylight as primary source of illumination". According to this article, "Numerous studies over the last 50 years attest to the importance of daylight in design. Research indicates that daylight can improve user satisfaction/performance and retail sales. These characteristics can make day lighted buildings more valuable and marketable. Day lighting also enables daylight harvesting and innovative control strategy that can generate 35-60+% energy savings. A daylight harvesting system decreases electric light contribution as the daylight contribution increases."
By using photosensors to determine the strength of light coming through the windows, it's possible to have the lights of the building automatically dimmed to produce the optimum conditions. The link to the article above demonstrates how this can work in practice and how the system can be designed.
Light management systems or lighting control systems are slow to be adopted but are designed to provide an intelligent network based lighting control solution. By utilizing a combination of occupancy sensors, relays, photocells, touchscreens, and online applications, lighting can be controlled in a more efficient manner than using simple switches and the cost of installing this equipment can be offset by the saving in power expenditure and increased lifetime of switches and light bulbs/tubes.
Automated systems also allow complex lighting systems to be arranged; so that in a meeting room if the projector is being used, the lights will automatically dim to provide the best conditions to view the presentation. In the event of an emergency, the lights can be controlled to flash to further alert the occupants.
If however you don't want to invest in an advanced lighting system, simply replacing existing lights with LEDs can save costs and the environment as show in this article. Typically, a Led bulb will last 10,000 hours whereas LEDs last 60,000. The actual energy saving costs are nil, but they are more environmentally friendly and produce a light that is less harsh and fits in well with trendy offices.
It's plain to se that lighting systems need to evolve, but since retrofitting is expensive and the benefits may not be immediately obvious, it's often only architects of new buildings who invest in them.