optical design and standards

8/8/2019 Optical Design and Standards

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Peter Thorns Head of Strategic Lighting Applications Thorn G.P.S. 20th April 2010

Opt ic a l Des ign and St andardsOpt ic a l Des ign and St andards

Materials in lightingMaterials in lighting


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Optical Design and Standards Peter Thorns 13-Apr-2010 20th April 2010 ZLD

Optical Design and Standards

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The purpose of materials in luminaires

Housing of components

Environmental protection

Optics for light emission control

Insulation of conductors

Enclosure appearance and aesthetics

Fixings supports and seals


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4

Controlling light

Optical control is achieved by various mechanical devices : reflectors, baffles,louvres, diffusers, refractor, etc... Many believe they want luminaires that will

provide the most light for the money. Unfortunately as efficiency increases,luminaire brightness usually does to and excess high angle brightness cancreate discomfort (glare) - enough in fact to defeat the purpose of additionallux. Thus fixture choice is a trade off between quantity (efficiency) and quality(comfort).


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Controlling light

Optical control is achieved by various mechanical devices : reflectors, baffles,louvres, diffusers, refractor, etc... Many believe they want luminaires that will

provide the most light for the money. Unfortunately as efficiency increases,luminaire brightness usually does to and excess high angle brightness cancreate discomfort (glare) - enough in fact to defeat the purpose of additionallux. Thus fixture choice is a trade off between quantity (efficiency) and quality(comfort).


6/91Optical Design and Standards Peter Thorns 13-Apr-2010 20th April 2010 ZLD


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Controlling light

Methods of optical control

Reflection

Ii Ir

Reflectance

Ii Io

Reflectance

Ii I

Reflectance




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Controlling light


Reflection

Diffusion

Ii

Io

Ii

Ir

Ii

I




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Controlling light


Reflection

Diffusion

Obstruction

Limiting

angle

Limiting

ray

Perforated

baffle




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Controlling light


Reflection

Diffusion

Obstruction

Refraction

Ii

I

r

i i'r'r

D

A

P

B C

Q

n1n

2

n3




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Controlling light


Reflection

Diffusion

Obstruction

Refraction




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Controlling light


Reflection

Diffusion

Obstruction

Refraction




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Controlling light


Reflection

Diffusion

Obstruction

Refraction




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Controlling light


Reflection

Diffusion

Obstruction

Refraction




14

A brief look backwards




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Metal vs. Plastic - metal

Why Metals?

Low cost

Long life

Appropriate

Versatile

Optics quality

Easy to process

Strength

Conductive

Reusable

Recyclable




16


Selection criteria

Photometric Performance:LOR

and distribution

Subjective feel: Iridescence,Milkiness,

Dark Light appearance, brightness

Cost: Material cost, fabrication ease/scrap

Service life




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Raw88%

Satin84%

Texture84%

Enhanced95%

Highspecular88%

LowSpecular88%




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MATERIAL TOTAL DIFFUSE

REFLECTIVITY REFLECTIVITY

% %

Multi-layer polymer mirror >98




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Metal vs. Plastic effect of reflectance


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Metal vs. Plastic effect of reflectance


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Metal vs. Plastic - plastic

Why Plastics?

Light weight

Corrosion resistant

Easy to process

Insulator

Low cost process

Less waste

Recyclable


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Plastics Development

1920S-1930S: polystyrene, acrylic, PVC

1940S: polyester, nylon, polyethylene

1950S: GRP, polypropylene,polycarbonate, ABS

1960S-1970S:high temperaturematerials, PPS

1980S-PRESENT: Blends


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PMMA PC PS PP PP TV20

Polymethylmethacrylat

Polycarbonate Polystyrol Polypropylen Polypropylen

visually high-qualitymaterial with a highaging and weather

stability

high-qualitytranparent

thermoplasticmaterial

good fortransparentapplications

environmentallycompatiblealternative to

PVC for interiorapplications

talcumconcentrated PP

Density g/cm 1.18 1.2 1.05 0.9 1.05

UV resistance high good poor poor medium

Temperature resistance good high good good/medium high

Light transmission high high high poor bad

Impact strength poor high bad high good

Scratch resistance high poor good poor medium

Chemical resistance poor poor medium high high

Surface glossy glossy glossy matt matt


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MATERIAL Transmission % Reflectance %

2mm Diffusion material 83 8

2mm Thick opal light 38 47


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Micro-prisms

Microprism/lenses are small lenses,generally with less than a millimetre

(mm) in diameter.

Excellent for deglaring indirect ordiffused light by redirecting high angleincident light down towards the working

plane. However the fact that it isinjection moulded often limits the sizeand shape available.

These materials do not hide the lamp.The prisms tend to just displace thelamp image or make 1 lamp look like 3.

The light can be split into the spectrum

at some angles as well.

(Pitch)0.4mm


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Micro-prisms

Can give improved optical control due toless aberration in prism forming

O i l D i d S d d


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MCPET

99% total reflectance

Relatively expensive

Glossy finish (so try to use it where youcant see it!)

MCPET is very easy to thermoform anddoesnt lose any of its reflectance

O i l D i d S d d


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WhiteOptics

97% total reflectance

Highly diffuse

Less expensive

Laminated on a steel or aluminiumsubstrate, therefore easy to use

The gloss level is only 8%, meaning youcould use it in place of textured painted

steel

O ti l D i d St d d


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Satinated material

High light transmission

Good hiding power

Low inner reflection

Impact resistant + UV stable

Light weight

Diffuser beads suspended in clearacrylic or polycarbonate material scatterthe light while the matt, textured finishreduces losses via reflection.

This has the added bonus of appearing

higher tier than opals.

It is very good when used as a lightchamber material, diffusing indirect light.

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O ti l D i d St d d


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Glass for opticsClear glass: 80-90%

Sandblasted or frosted:

70-85%

Opalescent: 55-80%

Solid Opal: 15-40%

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Glass



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Prismatic Glasses

+

OMS OMP OMW OME

Standard Semi intensive Semi extensive Extensive Super extensive



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Refractors

+

N1 N2 N3

Symmetrical optic With refractor N1 With refractor N2 With refractor N3



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Metal vs. Plastic Metal + Plastic



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Light Shaping Diffusers (LSDs)

Light shaping diffusers preciselycontrol and distribute light

Transmission can be in the region of92%

The structure of light shaping diffuserscan be considered as micro-lenses

Light shaping diffusers can becombined with other optical

components such as lenses andprismatics



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Light shaping diffusers preciselycontrol and distribute light

Transmission can be in the region of92%

The structure of light shaping diffuserscan be considered as micro-lenses

Light shaping diffusers can becombined with other optical

components such as lenses andprismatics

They come in various materials

including polycarbonate, acrylic andepoxy



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No good at hiding the lamp



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LEDs

Light produced by the diode has topass through a number of materials



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LEDs


Each material will have a differentrefractive index meaning

- Light is lost due to internal reflection atmaterial boundaries

- Light is bent, making optical control moredifficult



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LEDs





So it is important to match the RI of

materials as closely as possible



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LEDs





So it is important to match the RI of

materials as closely as possible



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LEDs

PMMA PC PS PP PP TV20

Polymethylmethacrylat

Polycarbonate Polystyrol Polypropylen Polypropylen

visually high-qualitymaterial with a highaging and weather

stability

high-qualitytranparent

thermoplasticmaterial

good fortransparentapplications

environmentallycompatible

alternative toPVC for interior

applications

talcumconcentrated PP

Density g/cm 1.18 1.2 1.05 0.9 1.05

UV resistance high good poor poor medium

Temperature resistance good high good good/medium high

Light transmission high high high poor bad

Impact strength poor high bad high good

Scratch resistance high poor good poor medium

Chemical resistance poor poor medium high high

Surface glossy glossy glossy matt matt



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LEDs

Short wavelengths, typically below450nm, result in yellowing of plastic

causing- Loss of light output

- Shift of CCT



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LEDs

Short wavelengths, typically below450nm, result in yellowing of plastic

causing- Loss of light output

- Shift of CCT

Short wavelengths, typically


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LEDs

The most common issues affectingquality in LED luminaires are

-

-

-



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LEDs


-

-

- Thermal issues (poor heat sink design)



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LEDs


-

- Electrical overstress (poor driver design)




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LEDs


- Chemical incompatibility





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LEDs





Due to the silicone based encapsulants(silicone lens) reacting with volatilehydrocarbons



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p g

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LEDs






Materials used in the luminaireconstruction can emit volatilehydrocarbons (conformal coatings,

adhesives, gaskets, secondary lens)



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p g

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LEDs






Materials used in the luminaireconstruction can emit volatilehydrocarbons (conformal coatings,

adhesives, gaskets, secondary lens)

These then diffuse through the siliconelens and react with the LED chip,causing discoloration and loss in lightoutput



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p g

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LEDs





The effect is dependant upon heat,photonic energy (brightness) andwavelength of light.

It occurs even when no phosphor ispresent, although not for red or greenLEDs.



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p g

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Why test?

In God we trust



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p g

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Breakdown mechanisms in materials

Oxidation (UV, thermal attack)



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p g

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Accelerated UV exposure rig



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Optical Design and Standards Peter Thorns 13-Apr-2010 20th April 2010 ZLD58


YellownessIndex

Flame retardant acrylic

Polycarbonate

Flame retardant acrylic

Acrylic styrene copolymer

0 1000 2000 3000 4000

5

10

15

20

25



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Chemical attack

The Acid attack test



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Chemical attack



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Chemical attack



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Chemical attack

Hydrolysis

Stress attack

Plastic viewed between cross polariser to revel stress inthe material.

The greater the number of fringes the higher is the stresslevel.



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Chemical attack

Hydrolysis

Stress attack

Concentrated stressPoorly annealed/tempered

Distributed stressWell annealed

Optical Design and StandardsB kd h i i i l


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Chemical attack

Hydrolysis

Stress attack

Modelling of profile ofa plastic toggle

Red spots showconcentrated stress

Optical Design and StandardsB kd h i i t i l


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Chemical attack

Hydrolysis

Stress attack

Micro-organism attack

Insect/animal attack

Fire attack



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FLAMMABILITY TEST

MATERIAL Fire Growth rate Total heat Release Smoke Growth rate Total Smoke prod'n Lateral Flame Spread Flam ing Droplets

FIGRA W/s (0.2MJ) THR MJ (600s) SMOGRA (m2s2) TSP m2 (600s) LFS Yes/No

Polycarbonate 3mm 0 0.3 0 26 N N

GRP Class 1 1mm 967 6.1 557 428 N N

Prismatic polystyrene 3mm 286 28 156 1513 N Y

PET 3mm 12 1.4 11 0 N N

PVC prismatic 3mm 99 1.8 138 253 N N

Acrylic sheet 3mm 2904 126 93 346 N N



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Chemical attack

Hydrolysis

Stress attack



Fire attack

Misuse

Tensile test



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Chemical attack

Hydrolysis

Stress attack



Fire attack

Misuse

Optical Design and StandardsBreakdown mechanisms in materials


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Chemical attack

Hydrolysis

Stress attack



Fire attack

Misuse

Optical Design and StandardsEnvironmental factors


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Environmental factors

Solid objects

Fingers

Dust



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Solid objects

Fingers

Dust



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Solid objects

Fingers

Dust

Moisture

Humidity

Drips

Jets

Immersion



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Solid objects

Fingers

Dust

Moisture

Humidity

Drips

Jets

Immersion

Optical Design and StandardsTP(a) and TP(b)


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TP(a) and TP(b)

The BS2782 Rate of Burning Test iscalled up by the UK BuildingRegulations, Approved Document B

covering Fire Safety, as a suitable testfor TP(a) and TP(b) rating assessment

Part B2 gives requirements for wall anceiling linings, with clause 6.10 to 6.16covering use of thermoplastic materials.Clauses 6.13 to 6.15 being specific tolighting diffusers



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TP(a) and TP(b)

Criteria for TP(a) rating

Criteria for TP(b) rating



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TP(a) and TP(b)

Clause 6.13 restricts the scope ofrequirements to recessedluminaires only.



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TP(a) and TP(b)

Clause 6.14 is concerned just with firerated ceilings for luminaire diffusersthis would really be a very special case.

Protection of the integrity of a fire ratedceiling would normally be provided by aseparate cover (or casing) over the backof the luminaire so that the luminaire isnot critical to the fire rating of the ceiling

system.



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TP(a) and TP(b)

Clause 6.15 is the main clause givingdetails to the use of TP(a) and TP(b)rated plastic materials



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TP(a) and TP(b)

Clause 6.15 is the main clause givingdetails to the use of TP(a) and TP(b)rated plastic materials

As you can see you are free to useTP(a) rated materials in almost allsituations without any specialrestrictions. The more flammable TP(b)

rated materials can still be used but onlyunder prescribed conditions Table 11and Diagram 27 give more informationto this.



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TP(a) and TP(b)

Clause 6.15 is the main clausegiving details to the use of TP(a)and TP(b) rated plastic materials

As you can see you are free touse TP(a) rated materials inalmost all situations without any

special restrictions. The moreflammable TP(b) rated materialscan still be used but only underprescribed conditions Table 11

and Diagram 27 give moreinformation to this.



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TP(a) and TP(b)

Clause 6.15 is the main clausegiving details to the use of TP(a)and TP(b) rated plastic materials

As you can see you are free touse TP(a) rated materials inalmost all situations without any

special restrictions. The moreflammable TP(b) rated materialscan still be used but only underprescribed conditions Table 11

and Diagram 27 give moreinformation to this.


European standards


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European standards

Societies Associations Standards Laws anddirectives

World CIE WTO ISO UN

Continents IESNA,CIEChina,

IESAustralia

NEMACCI

AMF

ANSI, ASTMCCC

ASI..

FederalGovernments

European (Lux Europa) CELMA

ELC

CEN EU

National,in eachcountry, f.e.

LiTG, CIBSE,LTG, SLG,AFE, NsVV, ...

ZVEI, FEEI,LIF, SdlE

DIN, BSI, ON,AFNOR, SNI,

National lawse.g. Buildingregulations


European standards


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European standards

Societies Associations Standards Laws anddirectives

World CIE WTO ISO UN

Continents IESNA, CIEChina,IESAustralia

NEMACCIAMF

ANSI, ASTMCCCASI..

FederalGovernments

European (Lux Europa) CELMA

ELC

CEN EU

National,in each country,f.e.

LiTG, CIBSE,LTG, SLG, AFE,NsVV, ...

ZVEI, FEEI, LIF,SdlE

DIN, BSI, ON,AFNOR, SNI,

National laws f.e.Buildingregulations,EnEV, ....

Exploitation Dedicatedlighting experts

Companieslighting experts

Appointednationaldelegates

Politicans,lobbyists


European standards


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European standards

CEN TC169 Light and Lighting

WG1 Terms and definitions

WG2 Lighting of work places

WG3 Emergency lighting

WG4 Sports lighting

WG5 Road lighting

WG6 Tunnel lighting

WG7 Photometry

WG8 Exposure to incoherentradiations

WG9 Energy requirements forlighting in buildings

WG10 Characterisation of

optical materials

Optical Design and StandardsEuropean standards


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u opea sta da ds

A CEN working group (WG10) islooking into producing a standard(s)with respect to the performance of

materials



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p

A CEN working group (WG10) islooking into producing a standard(s)with respect to the performance of

materials

The current work will cover

- Untreated base materials, including

- Aluminium

- Steel

- Plastic

- Glass

- Surface treated materials, including

- Polished materials- Anodized materials

- Vacuum metallized materials

- Painted materials

- Multilayer systems



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p

It involves measurement methods andperformance criteria

- Diffuse reflectance- Specular reflectance

- Colour

- Durability with respect to

- Temperature

- Humidity

- UV-exposure

- Abrasion

- Scratch resistance



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p

A material will be given a reflectanceclass (1 10) based upon totalreflectance



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Additional data will be provided by themanufacturer based upon durabilitytests

Optical Design and StandardsTrends in materials


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Use less materials

Use finished materials

Use efficient materials

Reduce range of materials

Recycle materials

Blend with efficient light sources

Optical Design and StandardsTrends in materials


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Use less materials

Use finished materials

Use efficient materials

Reduce range of materials

Recycle materials

Blend with efficient light sources

Thank-you

optical design and standards

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