This document provides information on fundamentals of energy efficient lighting. It discusses lighting types and their life cycle costs. It also covers lighting energy efficiency, efficient lighting technologies like LEDs, color temperature, color rendering index, typical efficacies of different light sources, use of reflectors, basic principles of lighting energy management including turning off unneeded lights and proper maintenance, and provides three case studies on lighting upgrades and the associated cost savings.

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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

4. 4
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
0
20
40
60
80
100
120
140
160
Tungsten LEDwarm Mercury Vapor LEDcool Fluorescent Induction Metal Halide HPS LPS
Lumens/Watt
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 ???????????