Efficent Outdoor Lighting

Efficient Outdoor Lighting Dr. Eng. Mohamed H. Helal New out-door lighting technology implementation will reduce great amount of energy consumed for street lighting . Street lighting works an average of 11 ~ 12 hours / day 365 days year , when use energy efficient product the payback will be within 1 ~ 2 years maximum

This information sheet suggests some of the things that can be done. Most of the suggestions apply to indoor lighting as well, where they also offer significant savings. There are several clear cut measures that can be taken to improve energy savings. New, much improved light sources are now available which provide considerably more light per unit of energy. Most newer fixtures offer better light control, putting light where it is needed rather than wasting a great deal of the light produced by the lamp ( Decorative Luminaries) Replacement of older fixtures and lamps with the newer, improved ones can greatly improve efficiency. Lamp efficiency is measured in lumens per watt. A lumen is a unit for measuring the amount of light; a watt is a unit for measuring the amount of electrical energy used. The lamp that gives the most lumens per watt is the most efficient lamp. The table below lists the lighting efficiency of some of the common lamps used for outdoor lighting: Type of Lamp Lumens per watt Average Lamp Life (hours) Incandescent 8 - 25 1000 - 2000 Mercury Vapor 20 - 50 12000 - 24000+ Metal Halide 60 - 100 10000 - 15000 High Pressure Sodium 60 - 140 12000 - 24000 Fluorescent 40 - 105 10000 – 24000+ Low Pressure Sodium 80 - 200 10000 - 18000 The less values are verified at lower power (the higher the power = more efficacy)

Fluorescent: Like metal halide, fluorescent is about four times as efficient as incandescent lighting. Fluorescent is commonly used for indoor applications, but outdoor usage is increasing. The best fluorescent and compact fluorescent (CFL) sources have several advantages over metal halide: longer life, a much shorter warm-up time to full brightness, ability to switch them on and off several times each night without significantly shortening bulb life, and a white light that is spectrally much less polluting than that produced by metal halide. High Pressure Sodium (HPS): Its main usage is outdoors, for street lighting, parking lot lighting, and other such applications. It is generally more energy efficient than metal

halide and is a good choice when true color is not critical. The light produced is an orange-gold color. It's very common in the U.S. Low Pressure Sodium (LPS): This light source is the most energy efficient of all, and it is an excellent choice when used with a quality fixture that controls the light output. The light is produced from glowing sodium gas within a tube, and so the LPS fixtures, for higher wattage lamps, are larger than the equivalent fixtures for HPS or MH. However, the LPS fixture is an excellent choice for street lighting, parking lots, and security lighting. There is no color rendering at all, but adequate color rendering is quite possible with system designs that also use a few MH or fluorescent fixtures to add a little white light. For equivalent fixtures (ones that offer the same amount of light and good light control), a 175 watt mercury vapor fixture could be replaced by a 100 watt HPS or a 55 watt LPS. The 35 watt LPS is equivalent to a 200 watt incandescent. It is easy to see that considerable energy savings is possible. Remember also that if the installation is glare free, a lower light level offers excellent visibility. More is not always better. Lighting controls: Controlling when and where the lights are used, how long they are on, and how bright they are can all be a major factor in conserving energy. Devices range from a simple on/off switch to computers programmed to control lights automatically. Turn lights off when not needed. Use individual controls rather than lighting large areas off of one switch. Use timers. Don't burn outdoor lights in the daytime. Use photo-sensors when possible. Some of the newer applications use motion sensors for room light control, and such systems are also feasible for outdoor applications. Dimming controls at demand light management that can dim out door lightings at late hours is the newest used technology world wide and has proof practicality and efficiency . Digital Electronic Controls : New Digital Electronic devices with High Frequency are available now to overcome HPS , Metal Halide and LPS lamps over current starting problem the new technology eliminates the RESONANCE HID lamps problem , the new digital controls will open large economic application for High Frequency HID lamps Electronic Ballast .. Maintenance: Finally, do not forget lamp and fixture maintenance as a factor. Keep the fixture clean from dust and dirt. Such contamination can reduce light output in some cases by up to 50 percent. *Cost Comparison Example: The decorative poles in Egypt are using Blend Lamps ( Blend lamps are kind of incandescent lamps with fluorescent powder painted ) Called FLORA Lamps they are not efficient and consume large amount of energy ( the 160W will consume 208 ~ 230W and the 250W will consume ( 325 ~ 360W) Service life time is about 1500 hour Efficacy is 20 Lumen/ W . Use of Blend Lamps or HID lamps with decorative lighting poles will result in excess heat that will damage the luminaries glass in addition to attract lots of dust and pollution that will reduce out put lighting efficiency . A good example is to replace the Blend lamps with High Power CFL this will results in great savings with longer service life with cost effective .. This example is assuming 10 hours per day use and 8 cents US$ per KW/H , blend lamps are used widely in Egypt for 5 , 6 and 8 meters poles .

Blend (Flora Lamp) Lamp Watt 250 160

Total Watt 325 208

High Power CFL Lamps

KWH/ KWH US$ year CFL Watt KWH/year year $/Yr 1186.25 94.9 85 310 24.8 759.2 $60.73 55 200 16

Saving/year $70.1 $44.73

Savings 74% 73%

Technical comparison Lamp Type

Lumen/Watt

Service Life

Blend Lamp

22

1500/h

> 200C

High Power CFL

85

8000/h

< 65C

Temperature CRI

Kelvin

ThdI

>80

5500

> 30%

>82

2700~6500

< 10%

Start Time 2~3 minutes when Hot 0.5 sec

Conclusion : Use of High Power CFL lamps (T5 Ho) instead of Blend lamps for decorative poles will result in an average savings of more than 70% from consumed lighting energy. It’s recommended to use 55W Tubes to replace Blend lamps of 160W and 85W Tubes to replace 250W Lamps. It’s recommended to use Tubes with 2700 Kelvin to give best visibility during fogging times . Use of HP CFL will overcome the heat problem that is responsible for breaking the Luminaries glass and carbonize the plastic covers resulting in decreasing light out put..

High Pressure Sodium High pressure sodium lamps are very efficient they can produce up to 140 lumen per watt , HPS lamps require ballast and igniter , a 250 W magnetic ballast of very good quality will consume minimum of 10% over the lamp power at rated voltage , if voltage will race up the consumed power will bi higher , each 1 volt will increase

consumed power by 1% while when voltage is less than nominated voltage ( 220V ) power will be less by 1% for each volt down , a 400W sodium lamp circuit will consume and average of 440W at 220V and about 480W at 230V and 520W at 240V this phenomena will shorten the lamp life dramatically .. Magnetic ballast require large amount of energy at start , a 250W lamp will require 3,5 Amperes while 400W lamps will require 5 Amps. HPS lamps will consume large amount of energy before the end of life , this phenomena will burn the magnetic ballast in many cases unless is equipped with thermal protection , before the end of the HPD lamp life the power will race up to 30% , this effect will take place for an average of 500 ~ 1000 hour before the lamp will stop to work ..

HID electronic ballast. Till recent times use of High frequency electronic ballast was not suggested because of the HID tubes resonance effect phenomena , this phenomena has restricted the use of High frequency electronic ballast with HPS and Metal Halide lamps , only low frequency electronic ballast was able to be used with HID lamps ( low frequency = 50Hz ~ 500Hz) low frequency electronic ballast is bulky and expensive ( high frequency allow the use of compact size transformers) . Electronic ballast will improve HID tubes service life , overcome the starting problem and improve the flakers effect , Electronic ballast with low frequency are expensive , economic payback seam to be difficult is used in large scale.

High Frequency Electronic HID ballast and resonance problem. Digital control technology was able to overcome the resonance problem and to make the HID electronic ballast more economic and visible , Digital High frequency HID electronic ballast with light demand control facility will present a large saving opportunity for street lighting , the main idea is to dim the light during non needed hours to save large amount of energy , use soft start technology made possible to overcome the large energy consumed during starting time , a typical 250W or 400W electronic ballast will consume 0.3 ~ 0.4 Amperes at start compare to 3,5 and 5 Amperes for magnetic ballast , soft start technology will increase HID lamp service life and allow high efficient use of the power resources with minimum energy losses . The soft start , protection system , stable voltage supply to lamp during operation will enhance lamp service life up to 50% compare to magnetic ballast and will eliminate the flicker effect . Electronic ballast will control the HID lamp during the end of lamp life and will cut off the power when lamps is dead to protect the ballast from damage . A great amount of energy is consumed during end of HID lamp life , as this period is

calculated to be an average of 750 hours that lamp will consume 30 % more energy , adding the extra energy due to over voltage during late night hours a sum of 50% extra energy is consumed during the last 750 hour of the HPS service life , Digital dimmable electronic ballasts will overcome this problem to as maximum power is controlled for certain hours of use during the night then power will dim down by 30% then by 50% during late night hours , this new technology is under application now from many countries and expecting to be wildly implemented due to simple way of control and ability to communicate with several levels of communication protocol.

Conclusion 1) Use of digital dimmable electronic HPS ballast will save a great amount of energy that can reach 50% from total consumed energy , 2) Will increase HPS lamps service life and will decrease line losses . 3) Will solve starting High energy need problem during rush hours 4) Central control of City lighting consumed power during peak hours will allow new energy management tool . 5) The fear of resonance effect is no longer to be considered , practical application results show no such phenomena with Digital HF Electronic Ballasts . For more information’s contact Prof. Dr. Eng Mohamed Helal [email protected]