Lighting Controls A GUIDE TO ENERGY EFFICIENT AND COST EFFECTIVE LIGHTING Lighting control technology and techniques can significantly reduce lighting energy use whilst maintaining the quality of illumination. Effective control systems can reduce lighting energy requirements by between 40% and 60% in most applications.
UP TO
60%
SAVINGS
CONTROLS, 11, 02
ENERGY EFFICIENT AND COST EFFECTIVE LIGHTING Lighting controls help ensure that lighting is delivered at the right levels for particular areas or workspaces when required. Up to 60% of the installed lighting load can be saved with proper use of the
appropriate lighting controls. Lighting controls can be used for a range of applications such as dimming, presence detection and to switch off lights when there is sufficient daylight.
LIGHTING CONTROL TECHNIQUES The main strategies for lighting control include: local switching and dimming, presence detection, daylight linked and time operated. The following diagram shows effective strategies for lighting control.
LIGHTING SYSTEM
AUTOMATIC CONTROL
AUTOMATIC PRESENCE CONTROL
DAYLIGHT LINKED
ON/OFF PHOTOCELL
ACOUSTIC
MANUAL CONTROL
TIME CONTROL
CONSTANT LUX DIMMING
LOCAL SWITCHING
PART LOCAL SWITCHING
TIME SWITCH
PROGRAMMED CONTROLLER
MICROWAVE
DYNAMIC INFRA RED
GROUP SWITCHING
MOVEMENT DETECTOR
ULTRA SONIC
INFRA RED
Each zone where lighting controls are to be used should be evaluated for the best strategy of control. Manual control includes the way the switches are linked to individual and groups of luminaires. Controllers can also be automated, and these can react to
presence detection, daylight availability or time of day. Multiple zone controllers use a communications protocol known as a ‘BUS’ system to link each component together. The main control strategies are outlined below.
Manual Control These are either permanently wired (such as the standard wall switch), or ceiling mounted pull switches, and can be used for switching or dimming. Part switching and group switching allows a certain number of luminaires or lamps to be controlled from local locations e.g. with appropriate separate ‘zones’, on bright days the luminaires closest to the windows would not need to be switched on and would therefore save energy. While manual controls are cheap to install they still rely on the occupants turning lights off when they are not needed. Raising awareness of the lighting
requirements and the profile of lighting energy use will be required to encourage manual switching. This can be done through well labelled switches and guidelines on what lights are to be used and when. Responsibility for turning lights on/off outside business hours needs to be allocated e.g. cleaners or security guards. One Irish retail chain uses different levels of lighting matched to store activities or the time of day. Lighting levels are increased in staff entrance areas during staff shift changeovers and levels are adjusted for store opening times, cleaning, re-stocking shelves and overnight security.
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Automatic Controls Presence control This can be used to: automatically switch lights on and off as people enter and leave an area or room manually switch lights on upon entry and automatically switch lights off when people leave an area or room. It is suitable for: rooms which are used infrequently, such as store rooms, washrooms, and other small areas rooms such as class rooms or rooms where the person entering has their hands free and upon exit has their hands full. Passive infra-red (PIR) units are low cost traditional presence detectors which can also have daylight sensor facilities.
Fig.2 Infra-red beam pattern, sufficient for smaller areas
Some types of PIR sensors can be set to keep the lights off when there is sufficient natural light and detect presence, automatically switching the lights on or off when a person enters or exits a space. Adjustable sensitivity is possible for both presence detecting and daylight sensing. The Link/Passive infra-red wall mounted (PIRWM) is a low cost, fast- fit presence detector to replace traditional wall switches. A built in sensor can be set to keep the lights off if there is sufficient natural light. This type of product does not require a neutral connection, so it can easily replace an existing light switch. It does not have a dimming facility.
Fig.3 Ultrasonic/Microwave beam pattern, appropriate for larger areas
The mounting position of automatic presence detectors (on the wall or ceiling) will be determined by the size and shape of the area: for small areas, infra-red detectors mounted on the wall, as shown in Figure 2, are likely to provide sufficient detection and the detector should be able to be ‘seen’ from all positions in an area for larger areas, ultra-sonic or microwave detectors, as shown in Figure 3, are more sensitive to movement and therefore more suitable for areas where small movements are made. The direction of the detector head needs to be considered as a sonic beam will detect movement through glass i.e. outside the office.
The most appropriate mounting position for infra-red detectors is shown in Figure 1. Be careful not to over space the detectors and follow manufacturers’ guidance, as not all types have the same covering pattern.
Daylight linked control Daylight controls/photocells linked to switch or dimming luminaires respond to daylight levels. The luminaires in a large workspace could be split into three lighting control zones. One zone along windows, a second zone in the middle of the room and a third zone at the back of the room. The luminaires in each zone can then adjust lighting levels depending on the natural light entering the space. Time control These are used to switch lights off when they are not required, such as at lunchtime or at the end of the day and in any situation with a regular period of occupation (always provide manual override to allow users to switch lights on if necessary).
Range up to 7m
Fig.1 Mounting position for infra-red detectors
CONTROL STRATEGY FOR AN OCCUPIED AND INTERMITTENTLY OCCUPIED SPACE
Person present Insufficient daylight – lights on
Person present Sufficient daylight – lights off
No-one present Insufficient daylight – lights off
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No-one present Sufficient daylight – lights off
control aPPLICations LIGHTING CONTROL STRATEGIES FOR A RANGE OF BUILDING TYPES Space/Area
Typical Pattern of Use
Automatic Control Upgrades from Manual Switching (Control strategies are listed in general order of preference)
Open plan office
Usually occupied
2, 5, 7, 9
Variable occupation
2, 5, 7, 9
Usually occupied
1, 2, 9
Variable occupation
1, 2, 5, 7, 9
Corridors
General
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Guest rooms
Variable occupation
2, 3, 4, 8
Restaurants and bars
Restaurants and bars
2, 3, 9, 10
Meeting / Conference room with various activities
Variable occupation
4, 5, 7
Reception or atrium
Usually occupied
2, 9
Canteens
Variable occupation
5, 7, 9, 10
Store rooms, laundry rooms, photocopying/sorting areas, toilets
Variable occupation
1, 2, 3
Waiting rooms
Variable occupation
1, 2, 3
General classrooms
Usually occupied
2, 3, 4, 9
Variable occupation
2, 3, 4, 9
Laboratories
Usually occupied
2, 3
Warehouses
Variable occupation
6
Retail area
Usually occupied
2, 3, 4, 9
Bookshelf areas
Variable occupation
2, 3, 9
Reading areas
Variable occupation
2, 3, 7, 9
Assembly and sports halls
Variable occupation
6, 9
Sufficient daylight available
Private office
Device
Insufficient daylight available
Lighting guides covering each of these building types are available from SEAI Automatic daylight sensing to ‘Off’ or ‘Dimming’
Offices
Manufacturing and Warehouses
Appropriate automatic occupancy sensing
Hospitality Business
Retail
Hospitals
Libraries
Schools
Sports and Leisure
‘Key-fob’ master control Dimming/scene setting
Time Operated
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EXAMPLES OF AUTOMATIC LIGHTING CONTROL DEVICES 1 Passive infra-red wall mounted
6 Microwave*
Functions
Functions
r eplaces the standard manual switch
presence detection manual on – auto off
n o ‘neutral’ connection is required
daylight sensing to off 15, 30 & 60 metre range
daylight sensing to off
a uto reduce range to avoid random switching
5-9 metre range 3 to 10 Amp loadings
7 Microwave*
2 Recessed infra-red
Functions
Functions
presence detection
presence detection
manual on – auto off
manual on – auto off
daylight sensing to off
daylight sensing to off
constant lux
constant lux
remote control
remote control
scene set
‘scene set’ - 6 metre range
7 metre range
8 Amp load 7 metre range
8 ‘Swipe-card’ or ‘Key-fob’ master control units
3 Surface mounted infra-red
Functions
Functions
c ontrols the flow of electricity to room systems
presence detection daylight sensing to off a djustable time delay light sensitivity remote control
9 Time-operated units
8 Amp load 7 - 12 metre range
Functions
4 Combined infra-red detector Functions presence detection remote controller dimming facility
c an range from simple 7 day mechanical time switches to more advanced digital devices
t hese control power to lamps based on pre-determined time intervals
10 Dimmer switches
5 Ultra-sonic*
Functions Functions
c ontrol light levels by controlling voltage to the lamps
presence detection
p re-programmable for time of day or for ‘scene-setting’ for general ambience
manual on - auto off daylight sensing to off remote control
* Be aware that these are very sensitive and will detect movement through glass, for example, someone passing by a window.
6 metre range (13 metres in corridors) 4
Definitions of terms Manual on – Auto off, requires the occupant to manually turn on the lights when entering the space, and the controller will automatically switch them off when nobody is present in the space. Daylight sensing to off, the controls will automatically switch the lighting off when the set level of daylight is reached with a short time delay in case of a temporary lower level, i.e. passing clouds.
Constant lux automatically dims the lighting (when luminaires have appropriate dimming ballasts) according to the amount of daylight that enters the zone. This form of daylight linking provides the greatest energy savings as the savings relate directly to the dimmed levels, furthermore the lighting will not suddenly go off. Remote control enables the lighting to be manually addressed via a hand held or wall mounted controller.
LAMP DIMMING
Typical energy savings when dimming fluorescent lighting are shown in Figure 4.
Energy consumption of the tube and ballast (%)
All dimming systems provide energy savings. Ensure that lamp and luminaire types are suitable for dimming. Some lamp types e.g. compact fluorescent lamps and high intensity discharge lamps can be dimmed with appropriate dimming control gear (ballasts).
100
80
60
40
20
0 0
10
20
30
40
50
60
70
80
90
100
Light Output (%)
Fig.4 Typical energy savings when dimming tubular fluorescent lighting.
DAYLIGHT BLINDS
Fig.5 Operation of daylight blinds on a bright sunny day, and on an overcast day.
Consider ‘daylight blinds’ for areas that receive good quantities of natural light, as they can eliminate the need for artificial lighting. These ‘Venetian-type’ blinds reduce glare and allow daylight to enter the space in a controlled way. The lower louvres can be closed to control glare while the upper louvres can be angled to reflect the sunlight against the ceiling to illuminate the room evenly, as shown in Figure 5. If the sky is overcast or clear without the sun the slats can be adjusted to enable the maximum amount of light to be deflected into the area and they also enable the occupant to view the outside.
SUMMARY An effective lighting control strategy will ensure that the level of lighting provided closely matches the needs of the users of the space. The installation of lighting controls, such as dimmers, timers,
motion sensors and photocells, or providing comprehensive switching schedules for manual controls can be a simple and efficient means of reducing lighting energy use and costs.
A tax incentive is available through the Accelerated Capital Allowance (ACA) scheme for approved lighting products. Further information and details of manufacturers and suppliers of eligible products are available from www.seai.ie/aca
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Accelerated Capital Allowance Eligible Products www.seai.ie/aca
