Experiences of LED Lighting Products

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1 Experiences of LED Lighting Products True stories and fairytales Tapio Kallasjoki Helsinki Metropolia University of Applied Sciences

2 LEDs are now widely used in luminance-based lighting solutions Obelux Oy

3 and in achitectural lighting accurately focused light beam coloured light without filter changing colour

4 and now in illuminance-based solutions Pictures: Philips, iguzzini, Osram, Valopää

5 LEDs in street lighting a number of test installations in Finland and abroad unsuccessful installations in the early stage (one demolished installation in the picture) big players are coming to the market expensive products suitable on residential streets

6 The efficacy of LED lighting systems is increasing rapidly Source: Tran Quoc Khanh, Technische Univesitaet, Darmstadt 2010

7 Lenseoptics can produce a very precise light distribution for a small LED light source, which means longer distances between poles and thus lower costs Source: Tran Quoc Khanh, Technische Univesitaet, Darmstadt 2010

8 In dimming the efficacy with LEDs is better than with high pressure sodium Source: Tran Quoc Khanh, Technische Univesitaet, Darmstadt 2010

9 Unfounded claims by some lighting companies You don t have to have so much light in LED lighting because LED lumens are different from conventional lumens You can t even measure LED lighting with a common lux meter

10 One possible explanation: mesopic vision Jan Evangelista Purkine Johannes Evangelista von Purkinje

11 The sensitivity of the human vision changes according to the surrounding luminances Source: HUT, Lighting Lab, Eloholma 12/2008

12 Recommended System for Mesopic Photometry Based on Visual Performance CIE 191:2010 ISBN This report deals with visual task performance based approaches to mesopic photometry with a major aim to establish appropriate mesopic spectral sensitivity functions to serve as the foundation of a system of mesopic photometry. A review of the most important visual tasks and the range of visual conditions typically encountered in the context of nighttime driving is given.

13 Examples of the S/P-relations (scotopic/photopic) Low pressure sodium... 0,25 High pressure sodium.. 0,65 Mercury vapour.... 1,05 Metal halide, warm white. 1,45 LED, cold light... 2,15 Metal halide daylight. 2,45 Source: HUT, Lighting Lab, Eloholma 12/2008

14 The light spectrum has an effect on reaction times in road lighting Source: David M. Keith

15 Mesopic vision prefer white light sources SOX=low pressure sodium, SON=high pressure sodium, CDM=metal halide (warm white), MH=metal halide (daylight) Source: Marjukka Puolakka and Teresa Goodman, CIE Conference 2010

16 Unfounded claims You can t measure LED lighting with a common lux meter Yes You can, if you have a good quality lux-meter

17 Picture: Greenpeace

18 Lighting

19

20 Over 90 % of the environmental effects are caused when the lamp is on Example: LV Halogen Source: Eco-design Requirements of EuPs, LOT 19, Final report, October 2009

21 Luminous efficacy of different light sources (IEA Annex 45 Guidebook 2010)

22 ErP-regulations are pushing us to use more energy efficient light sources CFL, LED, In the future more classes A+, A++, A+++? Halogen Incandescent

23 Efficacy of different light sources and their limitations in the future

24 HOW CAN A CUSTOMER CHOOSE THE RIGHT LIGHT SOURCE

25 Advantages of LED retrofit lamps long lifetime, if the cooling is done properly also the warm white light directed light, with lenses (compare to CFL) Challenges of LED retrofit lamps the heat sink must be in the lamp. in high wattage lamps the cooling system maybe can not be fitted to lamp dimensios when the lamp temperature rises, the lifetime of the driver gets shorter.

26 Many LED products are false advertised - customers will be dissappointed - LEDs may not come to the market as fast as expected (40 W incanscent 400 lm) (4 W LED-lamp 170 lm)

27 Lack of light distribution data Many small LED companies have no numerical data of the light distribution of their products lighting calculations not possible

28 Colour properties The colour of white LED changes during its lifetime (usually to blue) The peak wavelength changes with temperature The juntion temperature of LED (the input current, installation method, surrounding temperature) affects differently on different coloured LEDs, which changes the colour output and colour temperature of LED lighting fixtures and lamps.

29 Visual experience has shown that current CRI based ranking of a set of light sources containing white LED sources contradicts the visual ranking. CIE Report TC 1-62 CRI (Colour Rendering Index) is not a good tool for predicting colour rendering of white LED light sources.

30 COMMISSION INTERNATIONALE DE L'ECLAIRAGE INTERNATIONAL COMMISSION ON ILLUMINATION INTERNATIONALE BELEUCHTUNGSKOMMISSION New CIE TC 1-69 Colour rendering of white light sources To prepare a CIE Technical Report on recommended new metric (or system of metrics) including calculation procedures and justification for recommendation Suggestions more test surfice colours new calculation method of taking care of the large colour shift in single colour more than current two reference light sources maybe colour rendering properties can not be explained by a single number

31 Case: LED tubes in a classroom T8 linear fluorescent lamps have been replaced with LED tubes 18 W LED tube instead of 36 W fluorescent tube Energy saving 61 %

32 Results the luminous flux of the light source reduces 53 % CRI changes from 80 to 65 not fulfilling the requirements of the EN standard the colour of the light changes more glare estimate: UGR from 19 to 21 (made by T5-fixture, with same dimensions and light distribution) the light distribution of the fixture changes in this case the change is not very large because of a symmetrical light distribution with no uplight)

33 Test installation in a classroom Illuminance across the classroom (lx) Old T8-lamps (36W) New T8-lamps (36W) New LED-tubes (18W)

34 Illuminance and efficacy comparison Average illuminance (lx) in a classroom in different installations Efficacy (lx/w) in a classroom in different installations 700 1, , ,2 1 0,8 0,6 0, , Old T8-lamps (36W) New T8-lamps (36W) New LED-tubes (18W) Old T8-lamps (36W) New T8-lamps (36W) New LED-tubes (18W)

35 Also big players are coming to the market with LED tubes

36 Case: Four backlighted boxes 1. Small LED modules 2. Large LED modules 3. Fluorescent lamps 4. Neon tubes

37 Energy efficacy Energiatehokkuus 12,0 10,0 L/P (cd/m2,w) 8,0 6,0 4,0 2,0 0, Mainokset Huonelämpötila +20 Lämpötila 0 Lämpötila = small LED modules Blue = room temperature (+21 Celsius) 2 = large LED modules Violet = out zero degrees (0 Celsius) 3 = fluorescent lamps White = cold (-21 Celsius) 4 = neon lamps

38 Future challenges for LEDs efficacy progress heat problems lifetime estimation lack of standards colour properties and colour stability cost

39 Some LED products follow nicely the predicted depriciation curve Source: Narendran, LRC, Rensselaer Polytechnic Institute, 2010

40 and some don t Can a customer trust the predicted lifetime? Source: Narendran, LRC, Rensselaer Polytechnic Institute, 2010

41 The greatest threat is customer disappointment. If the lighting community can not handle the business correctly, the real breakthrough of LEDs can be postponed Source: IEA GUIDEBOOK ON ENERGY EFFICIENT LIGHTING FOR BUILDINGS, 2010

42 Thank you for your interest!