1. Lighting Control Indoor Lighting
Prepared by ISR – University of Coimbra
July 2017

2. Lighting Control Topics: Control strategies Manual Control
Automatic Control (sensors)
Energy Saving strategies

3. 1. Control Strategies
Lighting control technology and techniques can significantly reduce lighting energy use whilst maintaining the quality of illumination. Effective control systems can sharply reduce lighting energy requirements in most applications.

4. 1. Control Strategies Why use lighting controls?
Provide adequate lighting for the required tasks
Providing convenience and flexibility
Meeting building energy codes
Saving energy
Saving money

5. PROGRAMMED CONTROLLER
1. Control Strategies
LIGHTING SYSTEM
AUTOMATIC CONTROL
PRESENCE CONTROL
ACOUSTIC
MOVEMENT DETECTOR
ULTRA SONIC
INFRA RED
MICROWAVE
DYNAMIC INFRA RED
DAYLIGHT LINKED
ON/OFF PHOTOCELL
CONSTANT
TIME CONTROL
TIME SWITCH
PROGRAMMED CONTROLLER
MANUAL CONTROL
LOCAL SWITCHING
GROUP SWITCHING
Lighting controls help to ensure that lighting is delivered at the right levels for particular areas or workspaces when required. Up to 80% 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 can be provided by manual control using localized switches and dimmers; It can be automatic using timers, occupancy and photoelectric daylight sensors. And it can be provided by a combination of both resulting in optimized savings.

6. 1. Control Strategies
When selecting a control strategy there are four initial factors that must be considered alongside the type of use of the building/room:
1. Availability of daylight
2. Occupancy pattern
3. Number of occupants
4. Type of occupation including:
Variable occupation where occupants spend part of their time in the space
Intermittent scheduled relatively short stays (e.g. school classroom)
Full occupation where occupants are in the space for the entire working day
Intermittent occupation for an area visited only occasionally for short periods.

7. 2. Manual Control
Manual Control (can be used for switching or dimming)
Group switching allows a certain number of luminaires or lamps to be controlled from centralised locations.
Localised switching, where lights are controlled individually or in very small groups, can be implemented in a variety of ways with varying degrees of complexity and technicality:
Manual control
Hand held infra-red remote controls
Control through an internal network linked with a central control system
In areas with high occupancy, localised switching with variable lighting levels will be desired.
Localised control is especially beneficial is rooms with few occupants.
The ease of use and the speed of operation affect the way the occupants use the controls, e.g. where controls are difficult to use, occupants may choose lighting conditions, which minimise the need for control use, usually, a high illuminance level.
As a rule of thumb, the number of switches in a space should be not less than the square root of the number of luminaires. Thus 12 luminaires require at least 4 switches.
While manual controls are cheap to install they still rely on the occupants turning lights off when they are not needed.

8. 2. Manual Control
While manual controls are cheap to install, they still rely on the occupants turning lights off when they are not needed.
Studies in open plan offices have shown wide variations in user preference for lighting with some occupants switching their lighting on under almost all conditions and others doing so only when it is really necessary.
Raising awareness of the lighting requirements and the profile of lighting energy use will be required to encourage manual switching.
Individual control typically results in noticeable larger energy savings compared to central control of the entire space with only one switch. For example, on bright days the luminaires closest to the windows would not need to be switched on and would therefore save energy.
The ease of use and the speed of operation affect the way the occupants use the controls, e.g. where controls are difficult to use, occupants may choose lighting conditions, which minimise the need for control use, usually, a high illuminance level.
As a rule of thumb, the number of switches in a space should be not less than the square root of the number of luminaires. Thus 12 luminaires require at least 4 switches.
While manual controls are cheap to install they still rely on the occupants turning lights off when they are not needed.

9. 3. Automatic Control
There are three main ways to implement automatic control:
Centralised control systems – aim at regulating the light in several rooms, a floor or an entire building. Luminaries, sensors, and computers are connected by a network. (Bus-Based lighting control systems).
Stand-alone control systems – similar to centralised systems, but they are dedicated to the control the lighting only in one room or even parts of a room.
Intelligent luminaires – have their own control sensors that can signal on/off switching, dimming or others (e.g. color temperature changes). 1.
A dedicated computer or a building management system controls the luminaries. Switching and/or dimming can be related to time, daylight, and occupancy. Luminaries can be linked into groups or controlled in particular sequences. The length of time a luminaire is on can be monitored which provides important management information about energy consumption and maintenance. For safety reason, the emergency lighting installations must not be included in a centralised control system for a building 3.
The control can be overridden with a hand-held infrared controller. The luminaries can be programmed to provide a constant maintained illuminance throughout the maintenance cycle of the installation. Illuminance level and time delay, which operates when the occupancy sensor ceases to record movement, can be adjusted manually by using controls within the luminaire or remotely.

10. 3. Automatic Control Occupacy sensor linked Control
The most appropriate applications for occupacy sensors are in spaces where occupacy patterns are:
Intermittent: toilets, hallways, staircases, corridors, storage room and cellar.
Unpredictable: cell offices, meeting and conference rooms, school classrooms, laboratories.
Occupancy sensors are devices that perform three primary functions:
Turn the lights on when a room is entered
Keep the lights on while a room is occupied
Turn the lights off when a room is unoccupied.
The last function type of control is often very beneficial as it ensure the lighting is switched of at night and in the weekend.

11. 3. Automatic Control Occupacy sensor linked Control
There are three types of occupancy sensors:
PIR
Passive infrared technology detects occupancy by reacting to infrared energy sources (such as a human body) in motion.
Ultrasonic
The sensor emits ultrasonic sound waves that bounce off objects in the covered space, and then measures the amount of time it takes for the waves to return.
Dual
Occupancy sensors with multiple sensing technologies are usually referred to as 'dual technology' or hybrid devices.
Most commonly, PIR and ultrasonic technologies.
1. PIR (Passive InfraRed) occupancy sensors that operate by responding to the motion of infrared energy (or heat) produced by human bodies.
2. Ultrasonic occupancy sensors that operate by responding to the change in reflected sound waves in a space caused by a moving object. They do not require a direct line-of-sight to detect motion, unlike passive infrared sensors as they detect smaller motions. Ultrasonic sensors operate at frequencies above human sensitivity (20 kHz); typical operating frequencies are 25, 30, and 40 kHz [22].
3. Dual technology (hybrid) occupancy sensors combine PIR and ultrasonic technology. They keep lights on if one of the two technologies detects motion, and turn lights off only if neither technology detects motion (or the other way round). These products are more user-friendly as they reduce the likelihood of luminaries turning off while a space is occupied.

12. Passive Infra Red Sensing – tips for PIR Sensors placement
3. Automatic Control
Occupacy sensor linked Control
Passive Infra Red Sensing – tips for PIR Sensors placement
The PIR sensors must be located where there will be no obstacles blocking the person to be detected
PIR must not be able to “see” outside the desired detection area
Better detection can be achieved when a person crosses the detection areas

13. 3. Automatic Control Occupacy sensor linked Control
Ultrasonic detection – tips for ultrasonic sensors placement
Ultrasonic sensors can detect occupancy even though there might be obstacles between the sensor and the moving person
Undesired detection outside the controlled area should be avoided
They should be located away from air flows such air conditioning currents, fans

14. 3. Automatic Control Occupacy sensor linked Control
Dual-Tech Sensing - tips for ultrasonic sensors placement
Dual sensors can detect occupancy skipping obstacles due to their intrinsic ultrasonic capability
If occupancy must for the first time be determined by both PIR and ultrasonic technologies simultaneously, the sensor should be located where it can “see” the person
Mount it on a vibration proof surface

15. 3. Automatic Control Time Switching Control
There are two types of time switching control:
Time switching where the light are programmed to switch off after being on for a specified amount of time.
Particularly effective for spaces where unused light is frequently left on, such as rest rooms, closets, and corridors.
Time switching where the light system is programmed to provide lighting through designated periods, switching lights off during lunch breaks and at the end of the working day.
Time switch control is especially beneficial for switching off the lighting at fixed times when the space become unoccupied (for example in a museum or other building with fixed opening hours), at night or in the weekend.
Time delay switching is useful where lighting is only needed for a set period of time, for example when viewing a display.
Source: Control4

16. 3. Automatic Control Daylight linked control Maximize day lighting
Within a daylight-linked control system, photoelectric sensors measure the amount of daylight present and adjust the amount of artificial light accordingly.
Daylight linked control systems operate in two forms:
1. Photoelectric on/off switching where it is important to incorporate time delays into the control system to avoid repeated rapid switching e.g. caused by fast moving clouds.
2. Photoelectric dimming that ensures the sum of daylight and electric lighting always reaches the designed lighting level by sensing the total light in the controlled area and adjusting the electric lighting.
Automatic daylight linked switching or dimming in day lit spaces is beneficial in rooms with full occupation all the day e.g. in receptions and circulation areas.
The photoelectric sensors can either be placed centrally to control several luminaries, or mounted on each luminaire for individual control. Individual control of each luminaire is more expensive to install but provides precise regulation of the lighting level for each part of the area.
Photoelectric dimming provides larger energy saving than photoelectric on/off switching and the mode of control is more likely to satisfy the occupants

17. 3. Automatic Control Advantages: Disadvantages:
Improves the overall performance of an energy-efficient lighting system, achieving even greater energy savings;
Lowers running costs;
Provides automated performance of systems, does not require constant human interaction (i.e. “set it and forget it”);
Can gather useful data on performance, usage and even predictive maintenance.
Disadvantages:
Higher first cost in purchase of additional equipment for an installation;
Higher installation and commissioning costs, due to time to set the controls system correctly;
To manage the system effectively, may require expert consultants or training of staff;
Unless owner-occupied, there could be limited incentive for controls.

18. 4. Energy saving strategies
Use of Daylight

19. 4. Energy saving strategies
Use of Daylight
Provides better lighting quality than artificial light.
More comfortable colours due to the continuously changing luminance level, direction and spectral composition of the daylight.
Healthtier interiors and more wellbeing for the occupants leading to higher work performance and productivity.
Considering the building envelope and the lighting system with a full integration of daylight, will provide increased energy savings.
In new buildings, optimal use of daylight leading to energy savings and high comfort requires the building envelope and the lighting system are designed together.
Realisation of the full energy saving potential by use of daylighting requires good control of the artificial lighting.

20. 4. Energy saving strategies
Use of Daylight
For most visual tasks in commercial buildings, a window surface of approximately 20% of the floor area will provide adequate daylighting to a depth of approximately 1.5 times the room height.
The use of a horizontal skylight provides approximately three times the amount of daylight as a vertical window of the same size.
However, horizontal skylights collect more light and heat in summer than in winter which generally opposes desired conditions. Consequently, vertical or near vertical skylights, such as clerestories and roof monitors, are most often used.
Vertical or near vertical skylights designed according to the zenith angle of the sun can regulate the amount of daylight by obstructing the direct sunlight in the summer, and admitting and reflecting sunlight into the space in the winter.

21. 4. Energy saving strategies
Use of Daylight
Light ducts provide interior light by collecting sunlight through heliostats, concentrating the light through mirrors or lenses, and redirecting it to virtually any space throughout the building through shafts or fibre optic cables.
Additionally, light ducts are highly advantageous considering they transmit light without the transmission of heat

22. 4. Energy saving strategies
Potential Savings
Scheduling: Lights automatically turn off or are dimmed at certain times of the day or based on sunrise or sunset.
10 – 20 %
Lighting
Occupancy/Vacancy Sensing: Automatically turning lights off when people vacate the space.
20 – 60 %
Lighting
Multi-level Lighting/Dimming: Proving users one or more light levels than full-on and full-off.
10 – 20 %
Lighting
Daylight Harvesting: Automatically adjust light levels based on the amount of daylight in the space.
25 – 60 %
Lighting
Source: Lutron

23. 4. Energy saving strategies
Potential Savings
High-End Tuning: Set target light level based on occupant requirements in the space.
10 – 30 %
Lighting
Controllable Window Shades: Allows users to control daylight for reduced solar heat gain and glare.
Demand Response: Reducing lighting load in non-critical areas at times of peak electricity pricing.
30 – 50 %
Peak period
Source: [12]: pag:3
Plug-load Control: Automatically turning task lighting and other plug loads off when they are not needed.
15 – 50 %
Lighting
Source: Lutron

24. 4. Energy saving strategies
Potential Savings
Personal Light Control: Allow users in the space to select the correct light levels for the desired task.
10 – 20 %
Lighting
System Integration: Enabling multiple systems to share information and control each other to minimize product installed and maximize overall system performance.
5 – 15%
HVAC
Source: [12]: pag:3
Source: Lutron

25. 4. Energy saving strategies
Smart lighting
Smart lamps and luminaires combine technology breakthroughs in wireless communications and LEDs. Some of the smart features are:
Color tuning, dimming, gradually changing between color temperatures over time.
Integrated audio speaker, etc.
Connectivity for activation of services, security monitoring and data delivery.
Maintain constant luminous flux and operation that ensure the rated lifetime holds.
Wireless features implies that smart lamps and luminaires consume energy whenever mains power is switched on, even when they are not providing lighting but waiting for an instruction from a control device. Many systems also require a separate energy consuming gateway device for translating the communication signal between the control device and the lamps/luminaires
Another challenge is lack of interoperability between different manufacturers’ lighting products. Some systems including smart lamps, gateways, luminaires, controls, meters and management systems (software) rely on proprietary hardware and software. Other protocols are often used in building automation systems for commercial buildings.
Efforts to bring more standardisation and interoperability to the market are underway within manufacturers’ alliances and international standardisation organisations, but most are organised around each communication protocol.

26. Decision tree Daylight available? yes no Multi-occupant
Variable occupation
+++ Time switching
++ Localized switches
+ Photoelectric daylight linked
+ Occupancy linked
Intermittent scheduled occupation
+ Localized switches
+Occupancy linked
Full Occupation
+++ Photoelectric daylight linked
One or two occupants
Variable occupation
+++ Localized switches
++ Occupancy linked
+ Time switching
+ Photoelectric daylight linked
Full Occupation
++ Photoelectric daylight linked
Very low occupation density
Intermittent occupation
+++ Occupancy linked
++ Localized switches
+ Time switching
+ Photoelectric daylight linked
All occupancy types
Intermittent occupation
+++ Time switching
+++ Occupancy linked
+++ Localized switches
+++ Definitely recommended to produce savings
++ Could be expected to provide economies but rate of return on investment would be not as high
+ Needs consideration; might depend on a detailed examination of the installation