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Fundamentals of Energy Efficient Lighting

Presented By:

Ken Currie, PhD, P.E.

July 17, 2013

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Building Lighting Energy

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Lighting Type First Cost

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Lighting Type Life Cycle Cost

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Lighting Energy Efficiency

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Efficient Lighting

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Amount of Light

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Other Considerations

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Light & Color

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Color Temperature

Color Temperature is noted in degrees Kelvin* or °K

3,000°K - Warm White

3,500°K - Neutral

4,100°K Cool White

* The Kelvin Scale is defined as Celsius plus 273.

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Color Temperature Definition

• the electromagnetic radiation emitted from an ideal black body

• 1,700 K Match flame

• 1,850 K Candle flame, sunset/sunrise

• 2,700–3,300 K Incandescent lamps

• 3,000 K Soft White compact fluorescent lamps

• 3,200 K Studio lamps, photofloods, etc.

• 3,350 K Studio "CP" light

• 4,100–4,150 K Moonlight

• 5,000 K Horizon daylight

• 5,000 K tubular fluorescent lamps or Cool White/Daylight CFL

• 5,500–6,000 K Vertical daylight, electronic flash

• 6,500 K Daylight, overcast

• 5,500–10,500 K LCD or CRT screen

• 15,000–27,000 K Clear blue poleward sky

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Typical Color Temperatures

Incandescent ……... 2,750°K – 3,400°K

Fluorescent ……….. 2,700°K – 6,500°K

Mercury vapor ….. 3,300°K – 6,000°K

Metal Halide ……… 3,000°K – 4,300°K

High Pressure

Sodium …………...... 1,900°K – 2,200°K

Induction …………… 3,000°K – 4,000°K

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Color Rendering Index (CRI)

Color Rendering Index is a scale from 0-100 that indicates the accuracy with which a lighting source can reproduce colors. The higher the CRI value the more accurate the color reproduction.

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Color Rendering Index (CRI)

Typical high CRI values: 80 to 90

Typical good CRI values: 65 to 80

Typical poor CRI values: <65

Note: The CRI for standard Low Pressure Sodium lamps is extremely poor.

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Typical CRI Values

Incandescent …………….. 100

Fluorescent ………………. 60 - 90

Mercury vapor …………….15 - 30

Metal Halide ……………… 60 - 90

High Pressure Sodium ….. 10 - 60

Low Pressure Sodium ….. Negative

Induction ………………….. 85

LEDs……………………………. 30 - 60

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Lamp Life Comparison

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Light & Distance

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Light & Distance

The lighting level drops off as the square of the distance.

E = I/d2

Where: E = Illuminance (footcandles or lux) I = Intensity of lighting in Candelas D = Distance from the source

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Light & Distance

Therefore, even small changes in the mounting height of a luminaire can have a significant impact on the lighting level.

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Lighting Levels

• Specific tasks to be performed

• Time required for each task

• Speed and accuracy

• Age of occupants

• Safety and security

• Aesthetics

• System operating cost

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Lighting Sources

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Lighting Sources

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Sources Efficacy

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60

80

100

120

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Tungsten LEDwarm Mercury Vapor LEDcool Fluorescent Induction Metal Halide HPS LPS

Lum

en

s/W

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Lighting Source Efficiency

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Source Efficacy

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Reflectors

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Reflectors

• Reflectors allow the user to direct most of the light downward toward surfaces of interest instead of lighting the ceiling.

• Reduce electric consumption by reducing the number of lamps required for desired light output.

• 3 Types (Reflective Efficiency) – Standard Aluminum Reflector (86%)

– Reflective White Paint (91%)

– Enhanced Specular Aluminum (95%)

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LED Lamps – Efficacy

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Basic Principles of Lighting Energy Management

1. If you don’t need it, turn it off

- Employee Awareness, Sensors,

Timers, Photocells, Timed Switches, Energy Management Systems, etc.

2. Proper maintenance

- Group cleaning and relamping

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Basic Principles of Lighting Energy Management

3. Enhanced lighting control

- Photocells and occupancy sensors

4. More efficient sources

- Electronically ballasted fluorescent fixtures,

- Compact fluorescents - Induction lamps - Light emitting diodes (LEDs)

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Comparisons & Case Studies

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Incandescent Upgrades

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Case 1: Manufacturer

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Case 1: Manufacturer

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Case 1: Manufacturer

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Case 2: Automotive Components Manufacturer

Electric Rates: Usage: $.040/kWh Demand: $0.0/kW

Operating Hours of Fixtures: 8,760 hours/yr

Background: (31) Exit fixtures are equipped with (2) 20-watt lamps each

Power Rating: 40-watts Annualized Maintenance Cost per fixture: $25.81

Recommendation: Replace with (31) LED exit fixtures, each with (2) 2-watt LED lamps

Power Rating: 4-watts Annualized Maintenance Cost per fixture: $9.32

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Savings: Usage: 9,776 kWh/yr $391 / yr

Demand: 13 kW/yr $0 / yr Maintenance: $511 / yr Total Savings: 902 / yr

Implementation Cost: $1,513

TVA Rebate: $978

Simple Payback Period: 1.68 years (0.59 yrs)

Case 2: Automotive Components Manufacturer

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Case 3: Auto Parts Manufacturer

Electric Rates: Usage: $.065/kWh Demand: $12.47/kW

Operating Hours of Fixtures: 8,736 hours/yr

Background: There are (114) 400-watt metal halide fixtures throughout the facility

Power Rating: 450-watts/fixture Annualized Maintenance Cost per fixture: $19.71

Recommendation: Replace with (114) 220-watt T8 fluorescent fixtures

Power Rating: 220-watts Annualized Maintenance Cost per fixture: $11.76

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Savings: Usage: 229,058 kWh/yr $14,889 / yr Demand: 314.6 kW/yr $3,924 / yr Maintenance: $906 / yr Total Savings: $19,719 / yr

Implementation Cost: $45,326

TVA Rebate: $22,906

Simple Payback Period: 2.30 years (1.14 yrs)

Case 3: Auto Parts Manufacturer

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Questions ???????????