Intelligent Lighting Systems

Energy service companies have identified lighting (fluorescent for the most part) as the low hanging fruit of energy savings opportunities in aging building stock. Retrofits with T8s have been providing predictable energy savings and attractive simple paybacks for building owners for years. But while the tubes may have changed, the way we use lighting in commercial buildings really hasn’t. Commercial buildings still consume far more energy than necessary for lighting.

The U.S. spends about one quarter of its entire electricity budget on lighting, or $60 billion annually (U.S. Department of Energy, Consumer Energy Information: EREC Fact Sheets). The New Buildings Institute finds that lighting accounts for an average of 37% of the energy in a typical commercial building and as much as 50% in buildings constructed before 1986. The U.S. Department of Energy identifies lighting as the most important energy factor in the commercial sector (#DPE/EIA-0383(2001), December 22, 2000). Yet with so much to gain, we still aren’t readily able to rein in this costly energy load.

A colleague and noted energy, engineer recently observed that a $20,000 car had more intelligence than most $50 million commercial buildings. And he’s right. A vehicle’s engine management system responds in real time to multiple inputs (temperature, load, throttle position, exhaust pressure, etc.), processing thousands of data points every minute to ensure optimal combustion efficiency. By comparison we have been living and working in the dark ages in the world of commercial lighting.

The darker age

Until now, our ability to control lighting has been restricted to dimming an entire zone of lights based on a signal from a photo or occupancy sensor. None of these systems or sensors make decisions based on the dynamic environment that is a building. If the cleaners are three hours late, conventional systems won’t know it. They’ll just execute their simple program schedule and turn the lights on (in the absence of manual intervention). On sunny days, photo sensors, typically installed near the building perimeter, may dim the lights nearest the window, but they won’t adjust lighting levels towards the centre of the building, which means those areas can be over-illuminated on bright days. Individual occupants have limited, if any, control over lighting in their workspace, be it from personal preference or to adjust levels for particular tasks.

Designers do recognize that different areas have different general lighting needs: hallways don’t require the same levels of lighting as an office space, for example. However, the conventional approach is to adjust the density of the fixtures or the wattage of lamps in certain areas during the design and construction — a one-time fix.

Control by fixture

Advanced Lighting Control (ALC) systems deliver control right down to the level of the individual light fixture.

Using high efficiency bulbs and electronic dimmable ballasts, each fixture is addressable and programmable. Regardless of changes in layout, the operator always has control over how each fixture responds. In this way, advanced lighting systems provide point-of-use flexibility. Inputs are received by the central control system to enable adjusting individual or entire groups of fixtures, ramping levels up or down, on or off, in accordance with customizable settings, rates of dimming and pre-set task lighting levels. One of the collateral benefits of these systems is a reduction in lamp operating hours, extending lamp life and reducing maintenance costs.

One example of an advanced lighting control system is from Encelium Technologies, a Canadian lighting technology and controls firm based in Toronto. A system for commercial and industrial applications, the Encelium “ECS” connects all lighting fixtures to a central system that can control individual fixture light levels based on a variety of parameters. While it uses conventional occupancy and photo sensors, and electronic dimming ballasts, the system uses these devices to adjust light at each fixture, whether individually across the entire floor plate or set by zones. Because it is a software-based control system, control strategies are not dependent on hardware settings or fixture locations (today a closet, tomorrow a workspace). The Encelium ECS even allows for personal workspace lighting control via an innovative PC resident application (it detects keyboard activity to determine whether someone is occupying the workspace and displays a virtual dimmer control complete with presets). Systems like this can make decisions to constantly adjust to the building conditions at both the micro and macro levels.

Manufacturers quote the potential energy savings with advanced lighting control systems as high as 65% to 80%. There are also reduced lighting-related maintenance costs due to lower lamp burning hours.

Advanced lighting systems represent the next generation in energy management for lighting. With the ability to link to other building control systems, respond to utility load and pricing signals, and optimize light levels, all in real-time for varying building conditions, the future of intelligent control for commercial lighting is bright.

Article supplied on behalf of Encelium Technologies, Toronto. The author, Constantine Eliadis, P.Eng., is Chair of Sustainable Buildings Canada and a consultant to energy sector clients.