LEDs for Indoor

Scott RieseboschChief Technology Officer

CCT – what is it and why is it important for indoor

lighting? And why the extra “C”?

CRI – what is it and why is it important?

Are LED replacement lamps really a contender?

Some reliability data points to consider

Colour Temperature (CT)

• Colour temperature refers to shades of white light, and is measured on the Planck blackbody radiator scale (Black Body Locus, BBL)

• This scale measures the colour of a blackbody radiator (an ideal device with perfect absorption and emission) at various Kelvin temperatures

Example blackbody radiators at various color temperatures.

Correlated Color Temperature (CCT)

• Not all “white” light lies directly on the BBL• CCT refers to the Plankian black-body radiator colour temperature (CT) that is

closest to the colour of the white light source

Examples of CCTsRelationship between CCT & CT

Correlated Colour Temperature Effects

Color Rendering Index (CRI)

• CRI is an objective standard used to judge how well a light source renders colours compared to a black-body radiator or daylight• Incandescent bulbs are – by definition – equal to 100• Eight pastel colours are measured under the test light source

• CRI measures how much these colours are affected by the light source• Note: LEDs have fully saturated colour and actually pay a mathematical

penalty on the CRI system. Other standards for communicating colour are under investigation …

CRI of common light sources

75-90+Typical Warm White LED

95-100Halogen MR16

70-80Typical Cool White LED

100Incandescent

75-85Metal halide

79Daylight fluorescent tube

55Warm white fluorescent tube

25High pressure sodium

< 18Low pressure sodium

CRILight Source

LED replacement lamp performance

“Although there were a few exceptions, most of the lamps had

color quality attributes that were appropriate for replacing

halogen PAR lamps in most applications”

“All of the LED PAR38 lamps tested offer substantial energy

savings compared to halogen PAR38 lamps, and some are more

efficacious than compact fluorescent or ceramic metal halide

versions”

“It is reasonable to conclude that LED PAR38 lamps are (at least in

terms of performance) a viable option in most installations where

PAR38 lamps are used”

Source: USDOE Caliper Program Summary Report 20 November 2012

LED replacement lamp performance

“Many of the Series 16 products would be an effective energy-

saving alternative to incandescent BR30 or R30 lamps. Further, the

efficacy and color characteristics are similar to or better than

directional CFL lamps”

“Adding other factors such as dimmability and longer rated

lifetime makes LED BR30/R30 lamps the best solution for replacing

inefficient and soon-to-be regulated incandescent BR30 and R30

lamps”Source: USDOE Caliper Program Summary Report 16 July 2012

LED replacement lamp ROI

Can be under one year in applications of high usage, and

under 2 years in many applications

Well suited to applications where maintenance cost is high

Generally warranty is considerably longer than ROI

Cost of ownership is a slam dunk in most applications

How much does it cost to change a light bulb?

Reliability – can they hold up?

Plenty of reliability data now available

Advances in material science and deeper understanding of

failure modes that affect long term lumen maintenance and

colour shift over time

Energy Star program requires 6,000 hours of testing at

elevated temperatures

LED MR16 test lamps running continuously since August 2008

Reliability – can they hold up?

Reliability – can they hold up?

Reliability – can they hold up?

Reliability – can they hold up?

Reliability – can they hold up?

Over 44,000 hours later…

Thank you