Smart Guide to Lighting Sensors
18/03/2013 www.ukenergypartners.co.uk
UKEP Smart Guide to…
Lighting Sensors – what do you need to know?
• Types of Detection
– How they work
– Where & where not to use them
• Terminology
– Presence/Absence
– Photocells
• What to expect from a survey
• Next Steps
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Movement Detection
• Two Categories:– Passive– Active
• Different Technologies:• Active
– Ultrasonic– Microwave– Active Infra Red (Beam Break)
• Passive– Passive Infra Red (PIR)
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Ultrasonic
• Ultrasonic– “Radar” technology to monitor the controlled space that will respond to small
movements
– Emits ultrasound and looks for reflections
– Medium range
– Range dependent upon activity
• Will see small movements close up
• Requires more movement at longer distance
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Ultrasonic
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For
• Relatively low cost
• High quality presence detection
• Poor definition of detection area
• Doesn’t see through glass or thin office partitions
Against
• Poor for low incidence of false detections
• Affected by air movement
• Not good in electrically noisy environment
• Potential problem of interaction between similar units
Microwave
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• Microwave– Active presence detection – Sends out microwaves, looks at reflected signals– Sensitive to small body movements– Must be mounted on rigid/stable surface– Will “see” through glass/partitions– Medium/long range
• 20/30/60 metres
Microwave
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For
• Relatively low cost
• Very high quality presence detection
• Covers large areas – up to 60x60 metres
• No potential for unwanted interaction with other equipment
Against
• Poor for low incidence of false detections
• Not affected by air movement, but affected by moving metal
• Poor definition of detection area
• Sees through glass or thin office partitions
• Potential problem of interaction between similar units –frequency of operation (10.7 GHz)
PIR
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• Passive Infra Red– Operates on a combination of movement & heat
– Generally smaller areas
– Around 6 metres conical detection pattern
– Exception - specific Hi-Bay applications
PIR
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Pro
• Low cost
• Compact
• Easy to implement
• Reasonable quality presence detection
• The best for low incidence of false detections
• Works well in electrically noisy environment
• Very good definition of detection area
• Doesn’t see through glass or thin office partitions
• No unwanted interaction between similar units
Con
• Smaller area of coverage with exceptions
Comparing Modes of Detection
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Technology
PIR Ultrasonic Microwave
Cost Low Medium Medium
Detection Good Very good Excellent
No Detection Excellent Adequate Adequate
Precision Excellent Adequate Good
Implementation
(engineering)
Easy Medium Medium
Common Terminology
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• Presence
• Absence
• Passive Photocell
• Active Photocell
• Regulating Photocell
Common Terminology
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Presence or Absence
• What are we detecting?Presence or Absence
• In truth, neither – sensors are really detecting movement but these are the terms used.
• Presence Detector– Auto ON, Auto OFF - sensor will control lights
automatically.
• Absence Detector (also referred to as Semi Automatic)– Manual ON, Auto OFF – sensor requires manual
switch to initiate controls.
Common Terminology
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Photocells – daylight-sensitive cells built into your sensors
• Passive Photocell– Holds lights off in bright ambient conditions– Will not turn lighting off if light level rises whilst area is
occupied
• Active Photocell– Switches lights on and off according to ambient levels– Whether there is presence or not– Passing Cloud Timer
• To prevent oscillation of lighting• Fixed at the OFF delay time or 20 mins. maximum
• Regulating Photocell– Adjusts light output according to ambient level (dimming)– DSI, DALI or 1-10v (Analogue) versions
Next Steps
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• We hope this gives you an idea of how best to serve your site. The best sensor designs are the most thorough – use expert, impartial advice in planning and design.
• Energy saving varies according to area and occupancy, but typically ranges between 40 and 60%.
• If you want to know more, email UK Energy Partners at [email protected]
• Or call us on 0844 318 3000 now.