But a sensor built into the luminaire that automatically responds to its environment – whether it's occupancy, available daylight, time of day or other variables – and delivers just the right amount of light when and where it is needed -- is the perfect solution for reducing energy consumption and costs. Rather than applying controls as an afterthought the built-in approach maximizes energy efficiency.
Added intelligence within the sensor systems also greatly enhances the control ability of the facility operator. Remote control systems allow the setting of target light levels without a facility manager needing to get up on a lift and adjust dipswitches on sensors controlling 100+ fixtures. By supplementing the working space with only the amount of light needed to maintain a uniformly lit environment, tremendous energy savings can be realized when compared to existing installations which do not respond to changes in ambient light.
Image 3: Sensor driven lighting adjustments maintain constant illumination (70 foot candles on desks) while reducing output based on available daylight.
Now system-on-chip light sensor solutions provide a complete light sensing subsystem, including conversion of analog readings to a digital I2C output signal. This includes correction for any errors caused by the fixture's own imperceptible flicker, on an integrated circuit as small as 2mm square, and costs about the same, or even less, than a simple photosensitive component alone. Additionally, sophisticated filters automatically reject the 50-60Hz ripple typically produced by a building's fluorescent lighting systems, enabling the sensed light levels to more accurately measure the daylight that is entering the building.
Being fully aware of the lit environment also allows optimization that extends beyond energy savings. In integrated building management and control systems, the combination of proximity/motion and light sensing provides an abundance of data concerning the interior environment. Additionally, daylight sensing/harvesting combined with precise control mechanisms enable the lighting system to deliver not just the needed amount of light, but also offers the ability to tune the type of light to suit the activity and users in a particular space.
Intelligent lighting and existing light sources
Fluorescent luminaires are already in widespread use so it makes sense to integrate a system that can improve efficiency of these fixtures up to 50 percent through smarter lighting controls that match lighting to the demands of the business and environment. What is critical is a sensor system that connects to today's existing building management structure.
Although modern fluorescent lamps are highly efficient, adding the components to support dimming can be costly, and the nature of the ballast systems does not lend them to the faster on/off cycle times that would be considered ideal for motion sensor or proximity control scenarios. However, through the use of intelligent sensors, the technology senses a rise in ambient illumination and dims the luminaire in response; as the daylight increases, fluorescent light will decrease.
Environmentally aware, decision-directed, multi-sensor networks and optimized light will enhance not only the productivity of the built space, but also worker and group productivity, as well as increasing the health and well-being of individuals.