lighting systems


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lighting systems


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INTRODUCTION An essential service in all the sectors like industrial, domestic, commercial etc. The power consumption by the industrial lighting varies between 2 to 10% of the total power depending on the type of industry Major scope to achieve energy efficiency at the design stage, by incorporation of modern energy efficient lamps, luminaires and gears, apart from good operational practices


LIGHTING SYSTEM INCLUDES: Light Source Luminaries Ballast Lighting control Nature of surface/ surroundings


TERMS Lumen: Most common measure of light output Illuminance: This is the quotient of the illuminous flux incident on an element of the surface at a point of surface containing the point, by the area of that element Lux (lx): This is the illuminance produced by a luminous flux of one lumen, uniformly distributed over a surface area of one square metre Luminous Efficacy (lm/W): Measure of effectiveness of a light source. It is the ratio of lumen output to watt input Colour Rendering Index (CRI): color appearance of an object under a light source as compared to reference source. Its relative scaling ranges from 0 to 100.

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Light is an electromagnetic radiation Maximum possible light output is 683lm/W at 5500nm (G-Y region)

Lighting quality is dependant on::

Lighting quality is dependant on: Illumination level Uniformity Glare CT CRI


ENERGY AUDIT IN LIGHTING SYSTEM Collection of details regarding lighting system and transformers for audit area – details, location, types of lighting and transformer, rating, occupancy, no. of hours per day & no. of fixtures used Measure & document the lux levels at various locations by using luxmeters both during day and night – record the no. of lamps switched on Measure & document voltage, current, power factor and power consumption at various input points using load analyzer Compare the measured lux values with standard values & identify the areas which are over-illuminated & under-illuminated Collect & analyze the failure rate of lamps, ballasts & actual life expectancy level from the past data


Cont… Based on the assessment & evaluation bring out improvement options which could include: Maximize sunlight used by using transparent roof sheets, appropriate window design and building design Examine the scope for replacement of lamps by more energy efficient lamps with ne consideration tools like CRI, lux level, efficacy etc. Replace conventional magnetic ballasts by more energy efficient ballasts Selection of interior colors for more light reflection Modify layout for optimum lighting


Cont… Provide individual power group controls for lighting like ON/OFF control, group control switches, occupancy sensors, solar cell controls, timer based control, microprocessor based controls etc. Install input voltage controllers/ regulators Replace low efficient lamps by high efficient displays like LEDs


SOME GOOD PRACTICES IN LIGHTING Installation of energy efficient fluorescent lamps in place of conventional fluorescent lamps – good CRI + high luminous efficacy Installation of CFLs in place of incandescent lamps – longer lamp life + higher luminous efficacy Installation of metal halide lamps in place of Hg/ Na vapor lamps – high CRI Installation of HPSV lamps where CRI is not critical Installation of LED panel indicator in place of filament lamp -- Lesser power consumption, Withstand high voltage fluctuation in the power supply, Longer operating life Use of light controllers -- reduction in lighting level, when not needed Optimized light distribution -- Efficient luminaires Grouping of lighting system ( isolate from power system) -- controlled manually or by timer control


Cont… Optimum usage of daylight – ZONING -- air conditioning load Usage of sensors Usage of ballast in place of conventional ballast Use of microprocessor & computer based application Energy efficient luminaries Distinguish between requirements for working and safety light and go for remote control Lighting levels to match specific area requirements Lighting Transformer only for lighting loads


SIX BASIC RULES FOR ENERGY EFFICIENT LIGHTING Use the most efficient lighting source. Use the lamp light output effectively. Maintain lighting equipment in good order. Use well designed energy effective lighting schemes. Control the switching operation and usage of the lighting installation. Consider the effects of the surrounding décor.

1. Use the most efficient light source available::

1. Use the most efficient light source available: Incandescent fluorescent Blended lamp High pressure mercury vapor lamp High pressure sodium vapor lamp

High pressure sodium vapour lamp::

High pressure sodium vapour lamp: Most efficient light source. High efficacy. Faster re-ignition time. Longer life. Low C.R.I. Mainly used for Industrial lighting. Road lighting. Decorative lighting.

Lighting systems are used for::

Lighting systems are used for: Home Lighting Flood Lighting Display Lighting Road Lighting

Home Lighting:

Home Lighting Incandescent lamps are widely preferred because of: Excellent color rendition properties. Ability to create warm and cheerful atmosphere. Very little spill of light. Light is directed to areas where it is desired. Efficient use of energy.

Display Lighting:

Display Lighting Incandescent lamps are widely preferred because of: Strong directional properties. Sharp contrasts and shadows can be brought up. Optical control is possible. Not affected by dust collection. Lesser maintenance problems.

Road Lighting:

Road Lighting In road lighting, the light sources commonly used are the incandescent, fluorescent, blended light and mercury vapor lamps. Although the fluorescent lamp is slightly more efficient than the mercury vapor lamp in terms of lumens per watt, but being an extended light source it lends itself to poor control resulting in an inefficient lighting system. Hence high pressure mercury/sodium vapor lamps are more appropriate light sources.


Floodlighting: Sodium vapor lamps are preferred over Incandescent, high pressure mercury vapor because of: Excellent optical control. Very narrow beam distribution. Much greater efficiency.

2. Use the lamp light output effectively:

2. Use the lamp light output effectively

“if it looks right it is right”:

“if it looks right it is right” Though it is valid most of the time, the following check list of points will act as a reminder to help make the best use of energy— What are the light losses in diffusers or reflectors? What light distribution is required? Is a high quality paint finish used? Does the general construction of luminaire allow for the conditions in which it will be used? What are the control gear losses? Is the volume of an enclosed fluorescent lamp adequate? Is air conditioning included in the building services?

3. Maintain lighting equipment in good order.:

3. Maintain lighting equipment in good order. A study of a fluorescent lighting system was made, where different maintenance procedures were followed. The results showed that :- When luminaires were cleaned and relamped once every three years, the illuminance dropped to 60% of the initial value after three years. When luminaires were cleaned every one and half years and relamped every three year, the illuminance dropped to 68% of the initial value after three years. When luminaires were cleaned once a year and one third of the lamps replaced also once a year, the illuminance level was still 75% apart from an energy saving of 15%

4. Use well designed energy effective lighting schemes.:

4. Use well designed energy effective lighting schemes. The illuminance should be chosen according to task involved. The lighting scheme should be designed for an average level and then maintained at that level. The effect of aesthetic considerations in lighting scheme should be fully evaluated in terms of energy costs. Incorporate natural daylight, so allowing for lamps to be switched off for sometime. Preferable to use a ‘flexible’ installation to simplify and avoid the need for costly alterations to ensure energy effectiveness.

5. Control the switching operation and usage of the lighting installation.:

5. Control the switching operation and usage of the lighting installation.

6. Consider the effect of the surrounding décor.:

6. Consider the effect of the surrounding décor. The lighter the surface décor, the higher the reflection factor; less energy is therefore required for a given lighting result than when a darker décor is used. The smaller the area of the room, the greater the dependence upon the walls and ceiling to reflect light on the working plane (R.I). Luminaires having a greater direct luminous flux components are less dependent upon reflection from room surfaces and therefore more energy effective.

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