Operating Instructions

Laboratory Room Controller Owner's Manual
3-10 Siemens Building Technologies, Inc.
LRC Priority
When combining data from several inputs to determine occupancy, the LRC always applies
these rules:
• The controller works in the occupied mode whenever any one of the inputs indicates
occupancy.
• The controller works in the unoccupied mode only when all of the inputs indicate
vacancy.
Consider the following issues when using different methods of determining occupancy:
• Schedule: Schedules are often helpful, but rarely suitable as the only source of
occupancy information. In a situation where workers mainly follow a schedule, it is a
good start, but provisions must be made for exceptions to the schedule.
• Light Switch: Light switches can be very effective because there is no need to train
workers to take an extra step. However, there are scientists who need to work with
the lights off, so make sure all users are considered when deciding how occupancy
should be determined.
• Push Button: Using a push button requires workers to adjust the thermostat when
they want to work after hours. If those working in the laboratory are not used to
turning the ventilation up and down, they must be trained to do so. Some people may
feel that this method puts them in control; however others may find the extra step a
bother.
• Fume Hood Sash Opening: Using an open fume hood sash as an indication of
occupancy can be an important safety addition to an occupancy scheme. Fume
hoods should be closed when no one is working in the laboratory. If laboratory
workers are trained to close sashes as a matter of habit, then an open hood is a
reliable indicator of the presence of a worker. Also, the fume hood is the primary
device charged with protecting the lab worker; it does that best when the sash is
closed. Reducing the ventilation rate (one of the secondary means of protection)
when the fume hood is open is a questionable safety practice.
NOTE:
Workers may be in the lab but not working in a fume hood; therefore, sash height
may not always be a good indication of occupancy.
• Occupancy Sensor: An occupancy sensor can function exactly as the light switch
does, but does not depend on the laboratory worker flipping a switch. However, it is
important to carefully consider the type of sensor; for example, motion detectors may
not notice a scientist at work.