Innovations in Comfort, Efficiency, and Safety Solutions.
& Angela Lewis
July Issue - BAS Column
of the energy usage in a commercial building can be attributed to
systems that are operating under the assumption that the building is
“occupied.” Generally in an occupied mode, the lights are on,
HVAC systems are operating, and we are delivering code required
ventilation, as well as occupied heating and cooling setpoints.
On many sites, occupancy is determined through a schedule which often
starts early in the morning (in anticipation of the first occupants’
arrival) and runs until late at night after the last occupants (often a
cleaning crew) are gone. We know though that these assumptions
about occupancy are flawed. The actual building occupancy hours may be
much shorter than how the schedule is set up, and even during these
hours, not all spaces are fully occupied at all times. The end
result is often that we are conditioning space for many more hours than
is required, resulting in significant energy waste.
There are many solutions that can be used to attempt to measure building and zone occupancy. Some of these options include:
Of these options,
motion sensors are the best for control of lighting control systems,
while CO2 sensors are generally used for ventilation level
control. Using integration, it is possible to use the sensors
that are part of a lighting control system as an input for the BAS to
better operate the HVAC system. In many lighting control systems,
there are motion sensors installed in each major zone, and these are
fairly easily integrated so that the same inputs that are used to turn
on or off lights can also be used to reduce zone ventilation when an
area is unoccupied and make sure it is fully ventilated when
occupied. This is a great solution especially for areas such as
private offices, conference rooms and classrooms that may have variable
At Lightfair last week, we saw a number of new “next generation” lighting control solutions. These are systems that incorporate a sensor (generally for daylight and occupancy) into each fixture. Most of the systems connect wirelessly with wall switches to provide a complete, granular lighting control system. Each system is different but several come integrated with new LED fixtures, many are self-configuring and some even include temperature sensing at the wall and fixture. We expect to see these systems continue to improve, perhaps to the point where they can be used not just for occupancy sensing but also for people counting. This development makes integration between lighting and BAS even more valuable with the lighting control system becoming the main way to determine occupancy.
"Fixture Integrated Occupancy Sensor" - Courtesy of CREE.
About the Authors
Paul and Ira first worked together on a series of ASHRAE projects including the BACnet committee and Guideline 13 – Specifying DDC Controls. The formation of Building Intelligence Group provided them the ability to work together professionally providing assistance to owners with the planning, design and development of Intelligent Building Systems. Building Intelligence Group provides services for clients worldwide including leading Universities, Corporations, and Developers. More information can be found at www.buildingintelligencegroup.com We also invite you to contact us directly at Paul@buildingintelligencegroup.com or firstname.lastname@example.org
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