Energy Efficient Lighting

Energy Efficient Lighting

Overview Fundamentals

– Light Quantity– Light Quality– Glare– Energy efficiency– Lighting and Productivity

Inside-out Approach to Energy Efficient Lighting– End-Use

• Maximize daylighting• Deliver required quantity of lighting

– Distribution• Position lights effectively• Improve luminaire efficiency

– Primary Energy Conversion• Install high-efficiency lighting

Quantifying Savings

Light Quantity

Luminous flux– Quantity of visible light

output, lumens, lm.

Illuminance– Luminous flux divided

by area on which it is incident.

– 1 footcandle = 1 lm/ft2

Recommended illuminance increases as size and contrast of visual task decrease.

Light Quality Our eyes evolved

to see in natural sunlight; thus, we distinguish colors best in sunlight.

Color Rendering

Index (CRI) describes the effect of a light source on the color appearance of an object.

HPS and HBF Lights (Same Facility with Same Camera)

High Pressure Sodium High Bay Fluorescent Lights CRI = 22 CRI = 85

Glare

Glare is very high contrast between lighting levels

Avoid glare with parabolic luminairs, light shelves, and reflective blinds.

Energy Efficiency

Lighting efficiency = (lm/W)light x (CU)fixture/room

Efficient lighting:1. High lm/W 2. High CU

Characteristics of Superior Lighting

Correct Quantity High Quality Minimum Glare Energy efficiency

Superior Lighting

Superior Lighting Increases Productivity

Superior Lighting

Reno post office lighting retrofit.– Energy savings = $22,400 /year– Productivity improvement = $400,000 /year

Pennsylvania Power and Light– Energy savings = $2,000 per year– Sick leave decreased from 72 to 54 hours/year

Lockheed Martin office with daylighting– Energy savings = 4-year payback– Absenteeism dropping by 15%: 1-year payback

California schools – Test scores 20% higher in schools with daylighting

Chain of 100+ retail stores– Sales higher in stores with sky lights

Inside-out Approach to Energy Efficient Lighting

– End-Use• Deliver required quantity of lighting• Maximize daylighting

– Distribution System• Position lights effectively• Improve luminaire efficiency

– Primary Equipment• Install high-efficiency lighting

Utilize Existing Daylighting

Wright Brothers Factory, Dayton Ohio

Utilize Existing Daylighting

Bureau of Engraving and Printing, Washington D.C.

Utilize Existing Daylighting - By Turning Off Lights Near Windows -

Known• 10 465-W MH fixtures near

windows operating 6,000 hours/year

Action• Turn off 10 fixtures for 3,000

hours/yrSavings

• 10 fix x .465 kW/fix x 3,000 h/yr = 14,000 kWh/yr

• 14,000 kWh/yr x $0.10 /kWh = $1,400 /yr

Restore Existing Daylighting- By Replacing Discolored Glass and Fiberglass

with Corrugated Polycarbonate and Double Pane Lexan -

CP costs same as FG, but 10x more light

Install Skylights and Optimize Area Optimum skylight/floor area ratio

– Ranges from 1% to 6% – Increases with target lighting level– Decreases as lights are more efficient

Reduce Excess Electric Lighting

Known• Measured = 50 fc• Required = 30 fc

Action• Disconnect (1- fcreq/fcmea) % of

fixturesSavings

• Disconnect= (1 – fcreq / fcmea) = (1 – 30 / 50) = 40% of fixtures





Disconnect Blocked Lights

Position Task Lighting Above Work Areas

Reposition Lights Below Scaffolding

Use Reflectors that Push Light Onto Workplane

Replace acrylic with aluminum MH reflectors Add reflectors to fluorescent strip lighting

Paint Ceilings White

Install Occupancy Sensors in Seldom Used Areas

Known• Occupancy sensors cost $15 -

$80 each• 10 237-W T12 fixtures

operating 6,000 hours/year Action

• Install occupancy sensors to turn off fixtures for 3,000 hours/yr

Savings• 10 fix x .237 kW/fix x 3,000

h/yr = 7,110 kWh/yr• 7,110 kWh/yr x $0.10 /kWh =

$711 /yr

Install Photocells On Outdoor Lights

Known• Photocell switches cost about $15

each • 10 465-W MH fixtures operating

6,000 hours/year Action

• Install photocells which turn off fixtures for 3,000 hours/yr

Savings• 10 fix x .465 kW/fix x 3,000 h/yr

= 14,000 kWh/yr• 14,000 kWh/yr x $0.10 /kWh =

$1,400 /yr

Turn off Lights in Unused Areas





Replace Incandescent with Compact Fluorescent Lamps

CF lamps Use 75% less energy Last 8-10 times longer Result in less mercury emissions

Known• 100 100-W I lamps, life = 1,000 hours, cost = $1,

operating 6,000 h/yr Action

• Replace with 23-W CF lamps, life = 10,000 hours, cost = $5

Savings• 100 lamps x (.100 - .023) kW/lamp x 6,000 h/yr =

46,200 kWh/yr• 46,200 kWh/yr x $0.10 /kWh = $4,620 /yr • 100 lamps x 6,000 h/yr x ($1/1,000– $5/10,000) (h-

lamp)-1 = $300 /yr• $4,620 /yr + $300 /yr = $4,920 /yr

Replace T12 Lamps & Electro-magnetic Ballastswith T8 Lamps & Electronic Ballasts

T8 XP lamps with LBF electronic ballasts: Use 42% less energy and put same

amount of light on workplane Improve CRI and eliminate flicker

Known• 100 fixtures with four 34-W T12 lamps and electro-magnetic ballasts operating

6,000 h/yr Action

• Replace with four 28-W XP T8 lamps and LBF electronic ballastsSavings

• 100 fix x (.144 - .084) kW/fix x 6,000 h/yr = 36,000 kWh/yr• 36,000 kWh/yr x $0.10 /kWh = $3,600 /yr

Replace Metal Halide with High Bay Fluorescent Lights

High bay fluorescent (HBF) lights: Reduce energy use by 50% or more Improve CRI Reduce maintenance costs Stabilize light level Improve light distribution Can be turned on/off as needed, w/ occupancy or w/photocells

Replace Metal Halide with High Bay Induction Lights

HBI uses 50% less energy than MH to produce same illuminance HBI has instant restrike compared to 15-minute for MH HBI CRI = 0.90 compared to CRI = 0.65 for MH HBI lasts 100,000 hours compared to 20,000 hours for MH HBI has reduced lumen degradation compared to MH (90%

compared to 70% halfway through rated life) HBI light output is insensitive to temperature

Emerging Lighting Technologies: LEDs

Light emitting diodes (LEDs) currently used in: – Computer monitors and televisions– Exit signs, flashlights, etc.

Colored LEDs much more efficient than incandescent with colored filters. – California has replaced thousands of 150-W incandescent light bulbs that last

about 1 year in traffic lights with red, yellow and green LEDs that consume about 15 W and last about 5 years.

White LED efficiency currently between incandescent and T8 fluorescent lights, but:– Efficiency is increasing quickly, theoretical efficiency = 100%– Distribution efficiency ~ 100%– LEDs last about 5 times as long as incandescent lights.

LEDs are next lighting revolution

Quantifying Savings

1. Calculate number of proposed lights needed to deliver required footcandles.

2. Calculate annual energy cost savings from replacing the current lights.

3. Calculate annual relamping cost savings, including labor and material costs.

4. Calculate total annual cost savings including energy and relamping savings.

5. Calculate the one-time implementation cost of replacing the current lights.

6. Calculate simple payback of the investment.

Power Input Determined by Ballast – Not Lamp

Wattage on lamp is nominal value Power input determined by ballast power Example: 51-W Fluor F32T8 Low Output Electronic Ballast powering 2 x 32 W lamps.

– Power input including ballast = 51 W (not 2 x 32 W = 64 W) Example: 465-W MH ballast powering a 400-W MW lamp

– Power input including ballast = 465 W (not 1 x 400 W = 400 W)

Fluorescent Lamps Type Nominal

Power (W)

Rated Life (hr)

Mean Output

(lm)

CRI Cost ($)

4-ft T12 48-in T12 34-W 34 20,000 2,280 62 1.40 48-in T12 40-W 40 20,000 2,910 73 4.00 4-ft T8 48-in T8 32-W 32 20,000 2,710 78 1.90 48-in T8 32-W, long life, low merc 32 24,000 2,710 75 2.60 48-in T8 32-W, cover guard 32 20,000 2,625 78 11.00 8-ft T12 96-in T12 60-W 60 12,000 5,060 62 3.90 96-in T12 95-W 95 12,000 6,960 60 6.00 96-in T12 110-W 110 12,000 7,740 60 13.00 8-ft T8 96-in T8 59-W 59 15,000 5,310 75 7.80 96-in T8 59-W, cover guard 59 15,000 5,150 75 24.10 96-in T8 86-W 86 18,000 7,200 75 17.70

Fluorescent Ballasts Type Lamps Lamp

Power (W)

Ballast Power

(W)

Ballast Factor

Cost ($)

4-ft T12 Fluor F34T12 Electromagnetic 2 34 68 .87 4-ft T8 Fluor F32T8 Electronic (Low Output) 2 32 51 .75 $36 Fluor F32T8 Electronic (Normal Output) 2 32 58 .87 $15 Fluor F32T8 Electronic (High Output) 2 32 77 1.20 $36 8-ft T12 Fluor F96T12 Electromagnetic 2 60 112 .88 Fluor F96T12 Electromagnetic 2 95 203 .91 Fluor F96T12 Electromagnetic 2 110 237 .95 8-ft T8 Fluor F96T8 Electronic 2 59 110 .85 $25 Fluor F96T8 Electronic 2 86 160 .88 $29

Luminosity Determined by Lamp and Ballast

Mean output of lamp is nominal value Light output = nominal lm/lamp x ballast factor Ballast factor for fluourescents: high output ~1.2; normal output ~0.87, low output ~0.75 Ballast factor for HIDs (MH, HPS)= 1.0 Example: Fluor F32T8 Low Output Electronic Ballast powering 2 x 32 W lamps.

– Light output = 2 x 2,710 lm x 0.75 = 4,065 lm Example: MH 400-W lamp with nominal output 23,500 lm

– Light output = 1 x 23,500 lm x 1.0 = 4,065 lm

Fluorescent Lamps Type Nominal

Power (W)

Rated Life (hr)

Mean Output

(lm)

CRI Cost ($)

4-ft T12 48-in T12 34-W 34 20,000 2,280 62 1.40 48-in T12 40-W 40 20,000 2,910 73 4.00 4-ft T8 48-in T8 32-W 32 20,000 2,710 78 1.90 48-in T8 32-W, long life, low merc 32 24,000 2,710 75 2.60 48-in T8 32-W, cover guard 32 20,000 2,625 78 11.00 8-ft T12 96-in T12 60-W 60 12,000 5,060 62 3.90 96-in T12 95-W 95 12,000 6,960 60 6.00 96-in T12 110-W 110 12,000 7,740 60 13.00 8-ft T8 96-in T8 59-W 59 15,000 5,310 75 7.80 96-in T8 59-W, cover guard 59 15,000 5,150 75 24.10 96-in T8 86-W 86 18,000 7,200 75 17.70

Fluorescent Ballasts Type Lamps Lamp

Power (W)

Ballast Power

(W)

Ballast Factor

Cost ($)

4-ft T12 Fluor F34T12 Electromagnetic 2 34 68 .87 4-ft T8 Fluor F32T8 Electronic (Low Output) 2 32 51 .75 $36 Fluor F32T8 Electronic (Normal Output) 2 32 58 .87 $15 Fluor F32T8 Electronic (High Output) 2 32 77 1.20 $36 8-ft T12 Fluor F96T12 Electromagnetic 2 60 112 .88 Fluor F96T12 Electromagnetic 2 95 203 .91 Fluor F96T12 Electromagnetic 2 110 237 .95 8-ft T8 Fluor F96T8 Electronic 2 59 110 .85 $25 Fluor F96T8 Electronic 2 86 160 .88 $29

Coefficient of Utilization CU is fraction light emitted by lamps delivered to workplane CU is function of RCR, reflectance of walls, rw, and reflectance

of ceiling, rc, and the fixture RCR = 5 x h x (w + l) / (w x l) Reflectance:

CU values for 8-ft 4-lamp or 4-ft 2-lamp fluorescent fixture (www.goodmart.com)

Determine Required Number of Lights

Illuminance on a workplane, Ew (fc) is

Ew (fc) = [LPF(lm/fix) x N(fix)] x CU / Aw(ft2)Thus,

N = (Ew x Aw) / (CU x LPF)

Lamp Replacement Costs

The number of lamps that must be replaced each year, Nr, can be calculated as:

Nr = Num lamps x annual operating hours / lamp lifetime

Example: Calculate lamp replacement cost for 320 400-W MH fixtures if lights operate 8,000 hours per year. The cost of a 400-W MH lamp is about $23.The hourly wage for a skilled-trade electrician is $65 per hour, and it takes 30 minutes to replace a lamp.

Nr = 320 lamps x 8,000 hours/year / 20,000 hours = 128 lamps/yearCost = 128 lamps/year x ($23 /lamp + (30/60 hours/lamp x $65 /hour)) Cost = $7,104 /year

Natural Lighting Design

Illuminance on a workplane, Ew (fc) is

Ew = (Esl x Asl) x tskylight x twell x CUroom / Aw

Where, Esl can be calculated from:

Esl = Ih (W/ft2) x 110 lm/W (luminous intensity of sunlight)

Natural Lighting Design

LightSim Lighting Simulation Software: Uses TMY2, TMY3 or EPW

weather data Simulates illuminance on a

workplane, Ew (fc) Calculates number of hours and

fraction of time that natural lighting exceeds target illuminance.

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Energy Efficient Lighting