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1/7/2013 1 NATIONAL TECHNICAL UNIVERSITY OF ATHENS School of Electrical and Computer Engineering Lambros T. Doulos Lighting Controls Energy management Electric lighting consumes a significant amount of energy. About 25% to 35% of all electricity used in buildings is used for lighting Lighting also produces additional heat in buildings The heat from lighting typically accounts for 15% to 20% of a building's cooling load New legislation, codes, and standards (designed to establish minimum levels of energy efficiency) have been developed for responsible use of energy

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Page 1: NATIONAL TECHNICAL UNIVERSITY OF ATHENS - eap.grip2013.eap.gr/pdf/GR_Doulos_Lighting_Controls.pdf · NATIONAL TECHNICAL UNIVERSITY OF ATHENS School of Electrical and Computer Engineering

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NATIONAL TECHNICAL UNIVERSITY OF ATHENSSchool of Electrical and Computer Engineering

Lambros T. Doulos

Lighting Controls

Energy management

Electric lighting consumes a significant amount of energy. About 25% to35% of all electricity used in buildings is used for lighting

Lighting also produces additional heat in buildings

The heat from lighting typically accounts for 15% to 20% of a building'scooling load

New legislation, codes, and standards (designed to establish minimumlevels of energy efficiency) have been developed for responsible use of energy

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Lighting system design for energy efficiency

Key elements of lighting design for energy efficiency

Lighting Needs

Space design & utilization

Daylight

Light sources

Luminaires

Lighting controls

Operation & maintenance

Space design & utilization

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Daylight

Reflection &Redirection

Diffusion

Daylight

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Light sources

Luminous efficacy Color renderingLamp life

Lamp characteristics

Light sourcesColor rendering

Standard incandescentTungsten halogenCompact FluorescentTubular FluorescentMetal halide

High pressure sodium

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Luminaires

The efficiency of the luminaire is affected by

LampsBallastsSockets Wiring Optical media (reflectors, louvers, lenses)

Objectives of the lighting system

Effective task illuminanceCreation of a comfortable visualenvironment (temperature, colorrequirements, glare control)Accessibility

In the past, controls were used primarily to turn lights on or off, or for special purposes such as stage, theater, and conference room lighting.

More recently the use of controls has become an essential element of good lighting design and an integral part of energy managementprograms for lighting of commercial, residential, industrial, and exteriorareas.

Studies of buildings that have implemented control strategies haveshown that it is possible to reduce overall lighting energy consumptionby as much as 80% in some localities.

Lighting controls

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• IMPACT OF LIGHTING CONTROLS

• LIGHTING CONTROL TECHNIQUES

Lighting controls

• LIGHTING CONTROL STRATEGIES

• LIGHTING CONTROL EQUIPMENT

Lighting control strategies

• Energy Management Strategies

Predictable and Unpredictable SchedulingDaylightingBrightness BalanceLumen MaintenanceTask Tuning

• Aesthetic Control Strategies

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Predictable scheduling

Staff arrival and departure timesLunch periodsCleaning hoursWeekends and holidays

Energy Savings

Con

sum

ed P

ower

reach 40%

Activities occur routinely during the day, and luminaires are operated on a fixed schedule

Prevision for overridingthe schedule is provided(prevent to plungeoccupants into darkness)

Unpredictable schedulingUnassigned areas such as restrooms, copy centers, filing areas, conference rooms, break rooms, and retail store dressing rooms areused sporadically and are not readily scheduled.

Energy Savings

Con

sum

ed P

ower

Unpredictable schedulingstrategies usingoccupancy/motionsensors have yieldedenergy savings of over60% in some areas

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Daylighting

In the perimeter areas of buildings, part of the desired illumination canoften be supplied by daylight.

Illum

inan

ce (

lux)

High levels of daylightmust be present so thatsufficient illuminationfor the task remainsafter the electriclighting has beenlowered

Con

sum

ed P

ower Energy

Savings

Climatic conditionsBuilding formorientation and designPhotosensorControl design and installationActivities within the buildingSize and shape of control zones

The energy savings realized from daylighting depends on many factors

Peak power demand hours

Daylighting

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The size and shape of control zones are usually constrained by the rapid falloffof horizontal illuminance from the window wall.

The row of luminaires nearest the window should be controlled on a separatecircuit from those in the interior area.

Daylight level Artificial lighting level

Total lighting levelOff 50% 100%

Control zone depth

Daylighting

Brightness balanceThe design goal is to balance different brightness levels in order to

• either reduce glare and shadows or

• provide a luminous transition between two spaces having very differentbrightness levels (like in tunnel lighting).

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Lumen maintenance

Lumen maintenance control strategy calls for reducing the initial illumination of a new system to the designed minimum level.

Lighting systems are usually designed for a minimum maintained illuminancelevel. This requires the level of a new lighting system to exceed the designminimum by 20 to 35% to allow for lumen depreciation due to:

Lamp lumen depreciationLuminaire dirt depreciationRoom surface dirt depreciation

Energy Savings

Con

sum

ed P

ower Energy

Savings

Clean luminaire and relamp

Consumed Power without controlConsumed Power with control

Clean luminaire and relampIll

umin

ance

(lu

x)

Target illuminanceIlluminance level with controlIlluminance level without control

Wasted light

Wasted light

Illuminance level without control

1st year 2nd year 1st year 2nd year 1st year 2nd year 1st year 2nd year

Lumen maintenance

As lumen depreciation occurs, more power is applied to the lamps in order tomaintain constant output. Thus, full power is applied only near the end of the lumen maintenance period, significantly reducing energy use over the life of the lamp.

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Task tuning

1 luminaire, 2X58W Total: 116 W

4 luminaires, 2X26WTotal: 208 W

The lighting system is adjusted or tuned in order to provide local illumination as needed instead of uniform illuminances throughout a space.

380 Lux 280 Lux

Task tuning

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Aesthetic control strategies

Many spaces in commercial, institutional, and residential applications are usedfor more than one purpose. Different tasks require a variety of lightingconditions.

Aesthetic controls provide the means to adjust the lighting to:

Suit the purposeMaintain human visual performanceChange the mood of the space

Preset control systems allow for several lighting channels to be controlledsimultaneously. All channels are programmed to provide multiple moods orscenes. Each of these scenes can be recalled with the touch of one button

For reading tasks

For slide presentation

Recalled scenes

During conference

For opening tasks

Aesthetic control strategies

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Lighting Controls

LIGHTING CONTROL STRATEGIES

Lighting control with

Η/Υ(Predictable scheduling)

Occupancy/motion Sensors

(Unpredictable scheduling)

Manual dimming with remote

control(Task tuning)

Photosensor(Daylight)

• IMPACT OF LIGHTING CONTROLS

• LIGHTING CONTROL TECHNIQUES

Lighting controls

• LIGHTING CONTROL STRATEGIES

• LIGHTING CONTROL EQUIPMENT

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Lighting control techniques

Switching or Dimming control

Local or central control

Degree of control automation and zoning

After the control strategies the selection of the major controltechniques is particularly important in the specificationprocess. The following three categories establish the majorchoices:

Choosing communication protocol

• 1-10V• DMX• DALI

• KNX• LON

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Switching

SwitchingVia simple wall-box switchesremotely via relays

Suited to:Predicted SchedulingUnpredicted Scheduling (with occupancy sensors)Split-wired luminaires

Always remember: inconvenient switches are never used

By a control systemBy occupancy sensors

Switching for split-wiredluminaires

Levels: 0%, 50% & 100% Levels: 0%, 33%, 66% & 100%

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Dimming control

DimmingThe illuminance in each zone can be variedsmoothly and continuously to dynamically matchvisual requirements.

Suited to:Daylighting applications

Local or central control

Lighting controls can be implemented in buildings using either a local approach, a central system or some combination of the two.

The two approaches are distinguished both by the size of the controlled areas and by how the control inputs are integrated into the system.

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Local or central controlAll lighting control systems with local or central control are divided intoindependently controllable zones that contain three major components:

Power controllerThis is the "business end" of a control system that electrically changesthe output of the light sourceLogic circuitThis is the intelligence that decides when to supply electric lighting, and how much.Sensing deviceThe sensing device (such as a photosensor, an occupancy/motionsensor, or a timing device) sends information to the logic circuit. Two ormore of these elements can be combined in a single system

The communication and wiring system must link these components

Degree of control automation and zoning

Manual Highly automated

Cheaper

User friendly

Energy savings

vs

Override makes them friendlier

Small zones vs Large zones

FlexibleCheaper

(both in equipment and in installation costs)

More efficient to:Daylight

Task tuning

More efficient to:Scheduling

Lumen maintenance

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• IMPACT OF LIGHTING CONTROLS

• LIGHTING CONTROL TECHNIQUES

Lighting Controls

• LIGHTING CONTROL STRATEGIES

• LIGHTING CONTROL EQUIPMENT

Control equipment by space useAfter the strategies and techniques are decided, it is necessary to selectthe specific lighting control equipment to be employed.

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Control equipment based on expected lighting load profile

Control equipment for different building applications

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Manual Switching

The design and the location of the manualcontrol affects the energy consumption of the building.

The convenience and flexibility of switching greatly affect the extent of anylighting energy savings.

•Each separate office should have its own control switch

•Similar work areas should be grouped together on one circuit

•Adjacent luminaires should be placed on alternate circuits

: Luminaires in circuit A

: Luminaires in circuit B

Manual Switching

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•In three-lamp fluorescent luminaires, the middle lamps should beconnected to a separate circuit from the outside lamps.

•In four-lamp fluorescent luminaires, the inside pair of lamps should beconnected to a circuit separate from the outside pair

Manual switching

•Task areas with high levels of lighting should be on separate switches.

•Luminaires along window walls should be wired on separate circuits and be controlled independently.

•Effective labels can cause occupants to use simple wall switches.

Daylight level Artificial lighting level

Total lighting levelOff 50% 100%

Circuit A Circuit B Circuit C

Manual switching

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Timing Devices

The function of the timer is to controllighting in response to known orscheduled sequences of events, thatis, to turn off the lighting that is notneeded.

Timers range from simple integraltimers to microprocessors that canprogram a sequence of events for years at a time.

As a general rule, some form of override must be provided toaccommodate deviations from the preset schedule.

Timing and sensing devices

Photosensors

Photosensors use electronic components thattransform visible radiation (light) into an electricalsignal, which is used to control another system orlamp. There are two modes of operation:

•The photosensor output activates a simple on-offswitch or relay.

•A variable output signal is established and sent to a controller that continuously adjusts the output of the electric lighting in proportion the daylight.

Timing and sensing devices

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Photosensors

The performance of the photosensor can be complex because it depends from a lot of variables, such as:

The distribution of daylight and artificial lighting in the space in which it is placed

The spectral composition of lighting

The adjustment settings for the calibration of the control

The ambient light level

The field of view, spectral response and control algorithm of the photosensor

Placement of photosensor

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Wide versus narrow spatial responses

In practice, the reflectance of the workplane is not constant, but changes depending on the activities going on in the room.

Examples include a dark desktop that is sometimes covered with white papers, the colors of peoples' clothing such as a white shirt versus a dark suit, and even rearrangement of the room's furniture.

Occupancy/Motion Sensors

The primary function of occupancy sensors is to automatically switch offluminaires when spaces are unoccupied, so as to reduce energy use. Frequently, this method offers the best savings and payback of all controloptions.

The failure of anoccupancy sensorinstallation isalmost always a result of poorsensor placementor incorrectequipmentselection.

Timing and sensing devices

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Timing and sensing devicesOccupancy/Motion Sensors

Occupancy is sensed by audio, ultrasonic, passive infrared, or optical means.

These devices are designed to switch lights on as an occupant enters and keepthem on while he or she remains in the space. Lights are switched off after a preset time following the departure of the occupant.

Quiet activities such as word processing, reading, or using the telephone, however, may not be detected, and lights being switched off can frustrateoccupants in these situations.

These nuisance actions can be minimized by suitable product selection and proper sensor location.

Timing and sensing devicesOccupancy/Motion Sensors

The floor area covered by individual sensors can range from 15 m2 in individual offices or workstations to 200 m2 in largeclassroom or assembly spaces. Larger areas can be controlled byadding more sensors.

Occupancy/motion sensors can be used in combination withmanual switching (on or off), timers, daylighting sensors, dimmers, and central lighting controls.

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Central processors

Central processors can respond to a numberof complex lighting conditions in the space, collect power and energy-use data and supply summary reports for buildingmanagement.

Processors range in complexity from a microchip in a controller to a large computer.

For centralized systems, the processor is the device that assimilates the data, determines the required change, and initiates action to effect the change.

Input is received from the sensors, data are analyzed in accordance witha predetermined set of rules and a system change is initiated. Systems can also respond to manual switches.

Central processors

Processor (Logic circuit & Power controller)

Various lighting groups

Signal

Sensing devices

Existing protocols

Building Management System

DataRules

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• IMPACT OF LIGHTING CONTROLS

• LIGHTING CONTROL TECHNIQUES

Lighting controls

• LIGHTING CONTROL STRATEGIES

• LIGHTING CONTROL EQUIPMENT

Impact of lighting controls

Effects on the Whole Building

Electrical Equipment Effects

Power Quality

Human Performance Effects

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Effects on the whole building

Lighting can be responsible for a major portion of a building's HVAC load. Lighting electrical loads affect the initial cost of the HVAC system as well as its annual energy consumption.

It is important that the HVAC system and controls be designed to respond to changes in the operation of the lighting system from lighting controls.

Daylighting can increase the initial cost and the annual energy consumption if the daylighting system is not carefully designed. Indeed, payback can be longer with daylighting controls. For example, a daylighting system can increase the necessary summertime cooling load of a building by letting more heat into the building.

Many modern occupancy sensors have dedicated control outputs for the simultaneous control of lighting and HVAC equipment.

HVAC Effects

Electrical equipment effects

Controls that switch lamps on and off excessively can reduce fluorescent lamp life. Increased cycling does not decrease ballast life or reliability. The actual service life of lamps can be extended by the elimination of unnecessaryburning hours and dimming instead on and off.

Switching

Interference

Radio frequency interference (RFI) or electromagnetic interference (EMI) isinherent in all control systems that rapidly switch a portion of input power.

There are two areas of concern with regard to radio noise: conducted emissionand radiated emission. Conducted emission is the noise fed directly into the power line by the device drawing power from that line. Radiated emission is the electrical noise radiated by the lamps in the luminaire.

Control systems use passive and active filters to keep the conducted emissionswithin the allowable limits.

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Power quality

The designer should be aware of potential harmonics, as they canoverload the neutral conductor in three-phase electrical distributionsystems, which can damage itsinsulation and overheattransformers.

In practice no problems have actually been attributed to the generation of harmonics by lighting control systems to date, but designers and engineers should become familiar with the issues when using these advanced lighting technologies.

Human performance effects

Lighting control systems can have a positive effect on the workingenvironment, provided that they add to the comfort and the aestheticsof a space. Controls can have further economic benefit if the productivity of the occupants is increased.

Care should be taken when attempting to reduce energy use to ensurethat illuminance is not reduced below that required for visual tasks in the space. Audible noise, flicker, and source color changes caused bydimmer controls can also affect performance.

Control systems must be designed so that the lighting system can provide proper illuminance for various tasks such as reading, inspecting and assembling .

Illuminance

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Audible Noise

Flicker

Color Changes

The manufacturer should be consulted to minimize the noise produced by the control system. Noise control strategies include careful lamp selection, enhanced dimmer filtering, and remote dimmer locations.

Flicker is noticeable if the variation in light amplitude is sufficiently high. Evenimperceptible flicker can cause eyestrain and fatigue at 50 Hz. Lamps should be selected that minimize flicker. Electronic fluorescent ballastsshould be selected because they drive the lamps without flicker.

During lamp dimming, there can be a small shift in lamp color with fluorescentlamps (also in incandescent lamps ). This color shift is not usually consideredsignificant, but it is noticeable.They should not be dimmed to levels that alter the aesthetics of the space, causediscomfort to the occupants, or affect tasks in which color rendition ordiscrimination are essential. On the other hand, the shift in incandescent lightingto a lower color temperature by dimming can actually be desirable in certainapplications such as restaurants, where a warmer atmosphere can be inviting.

Human performance effects