All About Lighting I Havis-Shields Equipment Corp.

All About Lighting I

Havis-Shields Equipment Corp.

Overview

● About Light– Eye perception

● Lighting Technologies– Sources– Measures– Properties

● Applications– How to use the right source – Optics

About Light – Eye Perception

● All that matters is what the eye perceives● Color vs. contrast

– High light levels, we see color– Low light levels, we see contrast (B&W)

Color spectrum - www.photo.net


● Cones – See color, bright light (Photopic)● Rods – See B&W, low light (Scotopic)

Eye diagram - www.photo.net


● Rods and cones do not see the same!– Cones see yellow-green best– Rods see blue-green best

www.yorku.ca www.venturelighting.com


● Scotopic (low light) vision sees very little red!

Scotopic/photopic vision - www.4colorvision.com


● We are concerned with outdoor lighting– Photopic vision in bright areas– Scotopic vision in dim areas– Mesoptic (transitional) vision in most areas

● In short, we need lots of full-spectrum green, with some red and some blue for the best visibility

Lighting Technologies

● Artificial light sources (except halogen/ incandescent) are NOT full-spectrum!

Cool-white fluorescent spectrum - www.photo.net


● Halogen & Incandescent– High yellow, some green, some blue– Incandescent is slightly more red than halogen– Very low efficiency– Good for Photopic, bad for Scotopic vision

http://www.users.mis.net/~pthrush/lighting/glow.html


● Metal Halide and Xenon HID– High green, moderate blue, some red– Xenon HID is slightly more blue than std. MH– High efficiency– Excellent for both Photopic and Scotopic vision

Standard MH Enhanced MH Daylight


● Fluorescent– Moderate red, green, and blue– Can vary colors by changing phosphors– High efficiency– OK for both Photopic and Scotopic vision– Cool white is best for all-purpose viewing

www.squ1.com


● High Pressure Sodium– High red, moderate green, very little blue– Very high efficiency– Good for Photopic, terrible for Scotopic vision– All objects have strong orange cast

www.salsburg.com

Measures

● Lumen – Quantity of light (standardized)● Effective Lumen – Quantity of light (usable)● Color Temperature – Color of light● Color Rendering Index – Quality of light

Measures - Lumen

● What is a lumen?– Quantity of light– Defined at a specific wavelength (color) of light –

yellow● A lumen is NOT a lumen!

– Need to compare “effective” lumens– Studies based upon street lighting and reaction

time

Measures - Effective Lumen

● From IESNA:Table 1— Comparison of Light Sources High Roadway Lighting Level

Source Required Lumen

Multiplier* Metal Halide 1.0 Incandescent 1.5 Mercury 2.4 High Pressure sodium 3.9 Low Pressure Sodium 4.8

*Light level multiplier needed to produce the same reaction time as metal halide (for when metal halide provides a lighting level of 1.0 cd/m2).

● An example – Best Case:– 150W HPS = 16,000 lm => 4,100 lm effective– 150W MH = 13,000 lm => 13,000 lm effective– 150W Hal = 2,400 lm => 1,600 lm effective

Table 2— Comparison of Light Sources Low Street Lighting Level

Source Required Lumen

Multiplier* Metal Halide 1.0 Incandescent 2.9 Mercury 4.4 High Pressure sodium 7.8 Low Pressure Sodium 14.6

*Light level multiplier needed to produce the same reaction time as metal halide (for when metal halide provides a lighting level of 0.1 cd/m2).

Measures - Color Temperature

● All light sources we are concerned with are termed “White” light

● The color can be represented on a red-blue scale derived from optical pyrometry – Kelvin scale

● Note—does not account for green!

en.wikipedia.org

DaylightArtificial Light


● Color Temperature TableCOLOR TEMPERATURES

Description Degrees Kelvin

Clear Blue Sky 8000 to 27,000

Rainy, Misty Daylight 7200 to 8500

Overcast Daylight 6500 to 7200

Direct Sun + Clear Blue Sky 5700 to 6500

Summer Sunlight ( 9am to 3pm) 5400 to 5700

Summer Sunlight ( before 9am or after 3pm) 4900 to 5600

Cool White Fluorescent & Metal Halide 4200 to 4500

True White 3500

Warm White Halogen & Incandescent 2700 to 3000

High Pressure Sodium 2000 to 2200

Daylight:Blue to Very Blue!

Most Artificial LightRed to Blue

Optimal is right here!


● Summary:– Optimal color temperature is about 4,000-5,000K

for both light and dark lighting conditions– Higher color temperature is better for dim lighting– Lower color temperature is better for bright light– Good guideline, but does not account for green

● Light source must have lots of green to work well in all lighting conditions

Measures - Color Rendering

● CCRI = Correlated Color Rendering Index● Percent of colors that can be seen at a

specified color temperature● Most overall colors can be seen at 3,500K● A CCRI of 90 at 4,500K means that 90% of

all the colors that can be perceived at 4,500K will be perceived with this light source.

● A CCRI of 90 at 4,500K is NOT comparable to a CCRI of 90 at any other color temperature!

Measures - Color Rendering

● Good indication of the fullness of the spectrum

● Higher CCRI is better– CCRI > 65 is suitable for general lighting– CCRI > 80 is suitable for office lighting– CCRI > 90 is suitable for retail lighting

Light Source Typical CRI Halogen/Incandescent 100 Metal Halide – Double-ended 90+ Fluorescent 80-85 Metal Halide – General 65-80 High Pressure Sodium 20-22

Measures

● Summary:– For outdoor lighting, Metal Halide (and Xenon

HID) are far and away the best– Fluorescent can also be good, if the phosphors

are correct– Halogen is fair for bright lighting, but is very

inefficient, and not good for low lighting– High Pressure Sodium is good for bright lighting,

but very poor for low lighting

Properties of Lighting Sources

● Operational properties:

Light Source Efficiency On time (80% output)

Restrike time (80% output)

Lifespan (hours)

Halogen 6-12% <1 sec. <1 sec. 400-2,000 Metal Halide 40-45% <40 sec. <30 sec. 6,000-20,000 Xenon HID 38-42% <20 sec. <10 sec. 2,500-3,500 Fluorescent 35-45% <5 sec. <2 sec. 10,000-30,000 HPS 40-50% N/A N/A 20,000-40,000

Note: All lighting sources except for Halogen require a ballast to regulate light output. Ballast and lamp design will determine On time and Restrike time. HPS ballasts and lamps are generally not designed for rapid on or restrike.


● Performance:

Note: More stars indicates better performance.

Light Source Light Quality Optical control Relative efficiency

Overall suitability

Halogen ** **** * ** Metal Halide ***** **** ***** ***** Xenon HID ***** ***** **** ***** Fluorescent **** ** **** *** HPS * *** ** **


● Cost breakout:

Note: More dollar signs indicates higher cost.

Light Source Fixture cost Initial lamp cost

Lamp lifecycle cost

Overall cost

Halogen $$ $$ $$$$$ $$$$ Metal Halide $$$$ $$$ $ $$ Xenon HID $$$$$ $$$$ $$ $$$ Fluorescent $$$ $$ $ $$ HPS $$$ $$$ $ $$


● Summary– Metal Halide and Xenon HID are the highest

performance and lowest cost over the lifetime of the fixture

– Fluorescent can be a good choice, if suitable optical control can be achieved

– Halogen/Incandescent is the highest cost and lowest performance over the lifetime of the fixture

Applications

● Clearly, Metal Halide and Xenon HID should be used whenever possible

● Some fluorescents could be suitable for some applications

● Fixture must be designed to use any light source effectively– Bad fixture design can reduce the benefits of

using a good light source

Applications - Metal Halide

● Common wattages: 50-2000● Requires electronic ballast for instant-on and

instant-restrike– Only practical up to about 150W today– Future could include 250W or possibly 400W

● Moderate color shift and lumen depreciation● Lamps vary widely in quality and spec's from

manufacturer to manufacturer● Many color temperatures available● Higher than about 5,000K is inefficient● Some lamps are position-sensitive

Applications - Xenon HID

● Common wattages: 10-50● Small color shift and lumen depreciation● Lamps vary widely in quality and spec's from

manufacturer to manufacturer● Havis-Shields lamps are proprietary and

made specific for our applications● Our lamps are 4,200-5,000K for optimal

performance● Higher than about 5,000K is inefficient

Applications - Fluorescent

● Common wattages: 2-40● No color shift, small lumen depreciation● Havis-Shields lamps are proprietary and

made specific for our applications● Our lamps are 4,500K for optimal

performance● Higher than about 5,000K is OK● Lamps are temperature-sensitive, and may

need extra technologies to use outdoors● Lamps are long and slender, not suitable for

good light control

Applications - HPS

● Common wattages: 35-1000● Small color shift and lumen depreciation● Light quality is very bad for low-lighting

applications, so not recommended● No commonly-available lamps or ballasts are

available for instant-on or instant-restrike

Applications - Halogen

● Common wattages: 5-2000● No ballast required● Small color shift and lumen depreciation● Lamps vary widely in quality and spec's from

manufacturer to manufacturer● Lamps are typically 2,700-3,000K● Higher than 3,000K is not common● Lamps have short life● Lamps are good for optical control

Applications - Optics

● Common lamp designs:

Double-endedGood for wide flood lighting

Single-endedGood for spot lighting


● Reflectors– Reflect light into a specific pattern– Reflectivity of suface correlates with efficiency

● 78%, 85%, 90%, 94% Reflectivities– Potential for hot-spots

● Specially textured surfaces can improve uniformity– Common materials

● Hydroform● Spun● Sheet metal● Plastic● Glass ● White paint


● Controlling reflectivity– Polished & Anodized

● Moderate cost, 78-85% reflective● Sensitivity to dirt & fingerprints: Moderate

– Polished & Metalized● High cost, 90%+ reflective● Sensitivity to dirt & fingerprints: High

– Sheet Metal (Pre-Processed)● Low cost, 85-94% reflective● Sensitivity to dirt & fingerprints: Low

– Glass (Molded)● Moderate cost, 78%+ reflective● Sensitivity to dirt & fingerprints: Low


● Refractors & Lenses– Bend light into a specific pattern– Transmissivity correlates with efficiency

● 85%, 90%, 92% Transmissivities– Refractors direct light over an area

● Good to bend light up to about 30o

– Lenses good to focus light – or diffuse it● Good to collimate light or spread it uniformly

– Common materials● Glass (molded)● Plastic

– Can be expensive– Must be used with a reflector


● Flood lighting:

Spot

Flood

Beam angle(Spread)


● Flood lighting:

NEMA Type Classification

Angle range (degrees)

1 10-18 2 18-29 3 29-46 4 46-70 5 70-100 6 100-130 7 130+


● Single-ended lamp reflectors– Spot is typically 8 degrees max– NEMA types only apply to floods

● Double-ended lamp reflectors– NEMA type always apply– H x V format (Horizontal by Vertical)

● More sophisticated designs– Downward– Multiple-beam– Area


● Design methods– Computer design increases design quality– Ray trace over 1,000,000 rays per simulation

Summary

● Definition of light & spectrum● Lighting technologies

– Green is good● How to select the right source

– When in doubt, use Metal Halide/Xenon HID● Applications

– Direct light with reflectors, refractors– Describe reflectors with angles, NEMA types

● Questions?

All About Lighting I Havis-Shields Equipment Corp.

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