Transcript True Green Lighting

True Green Lighting
Professor CHUNG, Shu-hung Henry
Associate Dean, College of Science and Engineering
City University of Hong Kong
Overview
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Electricity consumption
Efficacy of light sources
How eyes work
Characteristics of different lamps
Cost estimation
Energy saving solution
Conclusion
Electricity consumption
Grid-based electric lighting consume about 19% of the total
global electricity consumption, 5% to 15% in industrialized
countries and 86% in developing countries [1].
Lighting
19%
Others
81%
Global electricity consumption
[1] Eino Tetri, "Concepts and techniques for energy efficient lighting solutions," Helsinki
University of Technology
Efficacy of light sources
Source: W.P. Lapatovich, “Metal-halide lamp design: atomic and molecular data needed,” Phys. Scr. T134(2009)
(Available at http://iopscience.iop.org/1402-4896/2009/T134/014024/pdf/physscr9_T134_014024.pdf)
How eyes work
Source: www.howard.k12.md.us/res/eyes/howeyeswork.html
Spectral luminous efficacy for
human vision
Source: http://hyperphysics.phy-astr.gsu.edu/hbase/vision/bright.html
Scotopic and photopic visions
Source: http://www.visual-3d.com/Education/LightingLessons/Documents/PhotopicScotopiclumens_4%20_2_.pdf
Metal Halide (MH)
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Lifetime: 5,000 – 22,000 hours
Efficacy: 100lm/W
Color rendering index (CRI) : 90%
Source:http://www.plantlightinghydroponics.com/eye-1000w5500k-hortilux-horizontal-metal-halide-lamp-p-1873.html
Source: www.archithings.com/search/osram+halogen+100w
High pressure sodium (HPS)
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Lifetime: 10,000 – 32,000 hours
Efficacy: 150lm/W
Color rendering index (CRI) : 22%
Source: Philips SON AGRO 430W HPS Lamps
Source: www.planetnatural.com/site/xdpy/kb/hps-lamps.html
Fluorescent (FL)
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Lifetime: 8,000 hours (drop of 10-20% light)
Efficacy: 100lm/W
Color rendering index (CRI) : 85%
Source: http://www.instructables.com/image/F95AE4AFCHYO8MX/Takeapart-a-Compact-Fluorescent-Bulb.jpg
Source: http://www.conservationphysics.org/intro/fundamentals.php
Light Emitting Diode (LED)
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Lifetime: 50,000 – 100,000 hours
Efficacy: 60lm/W
Color rendering index (CRI) : 70-80%
http://www.bombayharbor.com/productImage/04525480012540385
67/Amusement_Led_Lamp.jpg
http://www.f3images.com/IMD/Md_images/blue_moon_aquatics_90W_LED_lig
ht_spectrum.jpg
Green lighting
Energy
consumption
Light
performance
Investment
return
Environmental
aspect
HPS and LED
Source: http://ltiled.com/led/scotopic_vs_photopic/
Energy and light
Lamp
Photopic
Scotopic
CRI
Overall
MH
2
1
1
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HPS
1
4
4
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FL
4
3
2
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LED
3
2
3
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Component Cost (FL and LED)
Consider the lamp tubes only
I. T8 FL lamp
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Retail price: HK$30
II. Retrofit T8 LED lamp
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Cost of one 0.1W LED: US$0.13
Required output lumen: 1500lm
Required no. of LED: 200
Cost of LED for one lamp: US$26
Cost of mechanical housing: US$5
Total cost of one LED lamp: US$31
Retail price: US$80-90 (HK$640 – 720)
Running Cost (FL and LED)
Assumptions:
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12-hour service
$1.0/kWh
5-year service
I. T8 FL lamp (30W)
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Power consumption in five years: 657kWh ($657)
Replacement of the lamp tube: $30 x 3 ($90)
II. T8 LED lamp (20W)
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Power consumption in five years: 438kWh ($438)
Saving in five years: ($657 + $90 - $438) = $309
Projection of the cost
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LED Luminous efficiency : +10% each year
Cost : -10% each year
Thus, the overall cost reduction each year: -15% each year.
Projection of the cost of an LED lamp:
2010 : US$31 [HK$248] (Retail price : $640 - $720)
2011 : US$26 [HK$208] (Retail price : $536 - $604)
2012 : US$22 [HK$176] (Retail price : $454 – $511)
2013 : US$19 [HK$152] (Retail price : $392 - $441) *
2014 : US$16 [HK$130] (Retail price : $330 - $371) *
Challenges of LED lamps
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Color rendering index
Aging problem
Lifetime
Thermal management
Non-standard technical specifications (single supplier ?)
Implications:
 Is it really necessary to have a separate LED driver?
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LED lamp with integrated driver
AC-powered LED
How to save energy in this
FL-to-LED transition era ?
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Rule of thumb – reducing 1kWh consumption is easier than
generating 1kWh
Wait and see the development of LED technology
Small-scale trial with low-power LED light bulbs
Can we do something to help save energy?
Other:
 Disposal of FL lamps (Any incentive scheme?)
 Change all existing FL into LED lamps
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Environmental issue
Investment $$
Centralized lighting control
Meter room
MCB
Supply
mains
Lighting
circuit
Advantages of this concept
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Suitable for MH, HPS and CFL lamps
Short payback period (about 2 years)
Immediate solution to reduce the energy consumption by
20% ($$ and CO2)
No need to change or modify existing lighting equipment
and infrastructure
Optimal Lux level adjustment
*Note:
It is important to ensure that the voltage supplying to the lamp can
be continuously adjusted. Otherwise, the lamp life will be affected.
Conclusions
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LED lighting will be the future, but when?
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Technology, $$, eco aspects, …
Is that any available solutions that can immediately reduce
energy consumption?
Any room to reduce the required luminance level, 100lux 
80lux  50lux (but, we have to take care of the visually
impaired people)
Is it possible to set up an incentive scheme to make the
occupants dispose their CFL in an environmentally friendly
way?
Thank you