- 6.1 Overview
- 6.2 System Control
- 6.3 Integration into Building Automation Systems
- 6.4 Emerging Lighting Systems
Lighting affects several important aspects of a building. There is the aesthetic impact it will have on the building and its spaces, resulting in how occupants will perceive and react to the built environment. There is the more functional aspect of providing lighting to facilitate life safety and the work occupants undertake in and around the building. And finally, lighting is a significant consumer of energy. It is estimated that lighting accounts for 21 % of electric power consumption in commercial buildings and about 14% of electricity usage and costs in residential buildings. Unneeded and uncontrolled lighting within a building wastes energy and increases facility operational costs.
Different building uses will have different focuses for the building's lighting. These might be as part of building security, to maximize occupant productivity, energy conservation, or just to enhance the emotional reaction of occupants, for example, in retail stores or theaters.
A smart building entails a centralized lighting control system in all the building's usable square footage. The system should provide a dimmable lighting strategy. It also should have a global and zone light schedule and override capabilities. Lighting can also affect other technology systems, such as the need to cool spaces where lighting has increased the temperature. Lighting control systems provide lighting for occupants of the building as needed, but do it in an efficient manner, consistent with any applicable building needs and energy codes.
The requirement for lighting in a building varies by building type, spaces within the building, time of day, and occupancy of the building. Consequently, the control strategies and functions of a lighting control system reflect these variances and primarily involve:
b Scheduling: A control system may have a predetermined schedule of when lights are turned on and off.
b Occupancy Sensors: For building spaces where occupancy is difficult to predict (such as meeting rooms or restrooms), lights may be turned on and off based on a lighting control system device sensing occupancy.
b Daylight: To reduce the need and cost of lighting spaces, a control system utilizes natural light as much as possible. This is sometimes called daylight harvesting or daylighting.
b Window coatings: Spectrally selective window coatings, designed for hot climates with large amounts of solar radiation, work by selectively filtering out frequencies of light that produce heat while minimizing the loss of visible light transmission.
The lighting control system distributes power to the available lighting units in a typical fashion, but inserts digital control and intelligence in many of the control devices, such as the circuit breaker panel, wall switches,
Figure 6.1 Lighting in a building.
photocells, occupancy sensors, backup power, and lighting fixtures. The control system significantly increases the functionality and flexibility of the lighting system by providing digital control and intelligence to the end devices. For example, a reconfiguration of lighting zones is accomplished through software rather than the physical recabling. In addition, intelligent end devices allow more focused application of lighting control strategies to specific spaces within the building.