Energy Efficient Lighting
Overview
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Fundamentals
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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
CRI = 22
High Bay Fluorescent Lights
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
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Correct Quantity
High Quality
Minimum Glare
Energy efficiency
Superior
Lighting
Superior Lighting Increases Productivity
 Reno post office lighting retrofit.
– Energy savings = $22,400 /year
– Productivity improvement = $400,000 /year
 Pennsylvania Power and Light
Superior
Lighting
– 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/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
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 fixtures
Savings
• Disconnect
= (1 – fcreq / fcmea)
= (1 – 30 / 50)
= 40% of fixtures
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
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
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
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) (hlamp)-1 = $300 /yr
• $4,620 /yr + $300 /yr = $4,920 /yr
Replace T12 Lamps & Electro-magnetic Ballasts
with 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 ballasts
Savings
• 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
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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
Fluorescent Lamps
Type
4-ft T12
48-in T12 34-W
48-in T12 40-W
4-ft T8
48-in T8 32-W
48-in T8 32-W, long life, low merc
48-in T8 32-W, cover guard
8-ft T12
96-in T12 60-W
96-in T12 95-W
96-in T12 110-W
8-ft T8
96-in T8 59-W
96-in T8 59-W, cover guard
96-in T8 86-W
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

Fluorescent Ballasts
Nominal
Power
(W)
Rated
Life
(hr)
Mean
Output
(lm)
CRI
Cost
($)
34
40
20,000
20,000
2,280
2,910
62
73
1.40
4.00
32
32
32
20,000
24,000
20,000
2,710
2,710
2,625
78
75
78
1.90
2.60
11.00
60
95
110
12,000
12,000
12,000
5,060
6,960
7,740
62
60
60
3.90
6.00
13.00
59
59
86
15,000
15,000
18,000
5,310
5,150
7,200
75
75
75
7.80
24.10
17.70
Type
4-ft T12
Fluor F34T12 Electromagnetic
4-ft T8
Fluor F32T8 Electronic (Low Output)
Fluor F32T8 Electronic (Normal Output)
Fluor F32T8 Electronic (High Output)
8-ft T12
Fluor F96T12 Electromagnetic
Fluor F96T12 Electromagnetic
Fluor F96T12 Electromagnetic
8-ft T8
Fluor F96T8 Electronic
Fluor F96T8 Electronic
Lamp
Power
(W)
Ballast
Power
(W)
Ballast
Factor
2
34
68
.87
2
2
2
32
32
32
51
58
77
.75
.87
1.20
2
2
2
60
95
110
112
203
237
.88
.91
.95
2
2
59
86
110
160
.85
.88
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)

Lamps
Example: 465-W MH ballast powering a 400-W MW lamp
– Power input including ballast = 465 W (not 1 x 400 W = 400 W)
Cost
($)
$36
$15
$36
$25
$29
Luminosity Determined by Lamp and Ballast
Fluorescent Lamps
Type
4-ft T12
48-in T12 34-W
48-in T12 40-W
4-ft T8
48-in T8 32-W
48-in T8 32-W, long life, low merc
48-in T8 32-W, cover guard
8-ft T12
96-in T12 60-W
96-in T12 95-W
96-in T12 110-W
8-ft T8
96-in T8 59-W
96-in T8 59-W, cover guard
96-in T8 86-W
Fluorescent Ballasts
Nominal
Power
(W)
Rated
Life
(hr)
Mean
Output
(lm)
CRI
Cost
($)
34
40
20,000
20,000
2,280
2,910
62
73
1.40
4.00
32
32
32
20,000
24,000
20,000
2,710
2,710
2,625
78
75
78
1.90
2.60
11.00
60
95
110
12,000
12,000
12,000
5,060
6,960
7,740
62
60
60
3.90
6.00
13.00
59
59
86
15,000
15,000
18,000
5,310
5,150
7,200
75
75
75
7.80
24.10
17.70
Type
4-ft T12
Fluor F34T12 Electromagnetic
4-ft T8
Fluor F32T8 Electronic (Low Output)
Fluor F32T8 Electronic (Normal Output)
Fluor F32T8 Electronic (High Output)
8-ft T12
Fluor F96T12 Electromagnetic
Fluor F96T12 Electromagnetic
Fluor F96T12 Electromagnetic
8-ft T8
Fluor F96T8 Electronic
Fluor F96T8 Electronic
Lamps
Lamp
Power
(W)
Ballast
Power
(W)
Ballast
Factor
2
34
68
.87
2
2
2
32
32
32
51
58
77
.75
.87
1.20
2
2
2
60
95
110
112
203
237
.88
.91
.95
2
2
59
86
110
160
.85
.88
Cost
($)
$36
$15
$36
$25
$29
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
Mean output of lamp is nominal value
Light output = nominal lm/lamp x ballast factor
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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
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/year
Cost = 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.
Thank you!
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