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Total Light Management Combines Strategies to Shave Energy Use

Lighting is one of the easiest sources of energy efficiency in a commercial building. It's also an important source of points for LEED certification. Denis Du Bois takes a look at Lutron's Quantum system for "total light management" in commercial buildings.

This is a highlight from the Building Priorities Briefing.


Denis Du Bois: [At Greenbuild 2009] I took a long look at Lutron's Quantum system for commercial buildings.

The lights are connected to daylight sensors -- little devices about the size of a quarter that attach to the ceiling. When there's a lot of daylight -- in a cubicle, for example -- the artificial lights are dimmed to save energy.

Those components also communicate with automated blinds that raise and lower to reduce heat gain but still get the most out of the available daylight. And of course occupancy sensors, so if a room's vacant, the lights turn themselves off.

Lutron's Michael Jouaneh says, managing the total light in a building can reduce lighting energy use by 70 percent.

Michael Juaneh: ...To get the 70 percent, you need to combine several light management strategies. Occupancy sensing definitely being one--key one. Daylight harvesting is another key one. We also, with our digitally addressable dimming ballast, can do light level tuning. That's where you set the target light level in this space--so, you tune the lights down to meet a specific foot-candle level in this space.

Lutron wireless sensor photo on EnergyPriorities.com

Lutron makes the sensors needed for "total light management" strategies, such as daylight harvesting and occupancy sensing. Wireless devices make it less costly to retrofit lighting controls into existing buildings.

Denis: You also need scheduling, preferably with an astronomical clock to adjust for the seasons. And "high-end trim" ...

Michael: High-end trim is where you set the maximum light level in a space, so instead of 100 percent full light, set it to 80 percent full light, which is not really noticeable at all by the occupants, but you save about 20 percent in energy.

Denis: And incidentally, many of these also prepare your building to participate in demand response.

But the even stronger justification for integrating a lighting control system into a building is worker productivity.

Michael: The productivity improvements are tremendous because the salary of the workers in this space represents over $300 per square foot in costs, OK. So, if you just simply improve productivity by a little bit, that adds up to a lot of money.

Denis: Lutron's coming out with a wireless daylight sensor in January 2010. Wireless devices make it less costly to retrofit lighting controls into existing buildings.

And here's an interesting stat for you: 100 percent of the buildings in the United States are existing buildings. Think about it.