Light Pollution

Sky Glow

•Waste of light

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Sky Glow

•Nocturnal animals disrupted by the abnormal night lighting▫Sea turtles

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Sky Glow

•Some studies suggest human health is negatively affected ▫Disrupted circadian rhythms

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Negative Impact on Wildlife

•Animals and plants live by a rhythm based on a 24 hour cycle

•Interferes with migration, mating, foraging for food, and sleep

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Sky Glow

•Loss of starry skies  

Spillover

•Light falling where not intended or needed ▫Light trespass

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Glare

•High levels of glare can decrease visibility

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•Security concern

Glare

Inefficiency•Cost of useless light

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Lighting

VOLT: the force that moves electricity▫Like water pressure

•240 volts for heavy appliances

Lighting

120 volts for house voltage

Lighting

12 volts is low voltage and safe

Lighting

CURRENT or AMPERAGE: the flow of electricity▫Like water flow

Lighting

•Watts are a measure of POWER▫Volts x Current = Watts

Lighting

•Lumen is a measure of light▫As perceived by the human eye

Cost of Lighting

•12v, 10w halogen: 200 lumens•12v, 1w LED: 50 lumens

Types of Lamps▫Incandescent▫Fluorescent▫Light Emitting Diode (LED)

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Incandescent•Heat a tiny coil of tungsten

metal inside a glass bulb to produce light▫90% heat▫10% light

•Short lives

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Fluorescent•Electric current

conducted through tube of mercury and argon gases▫No filament

•3x to 4x more efficient than incandescent

•10x longer life

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Fluorescent•Require energy boost

from ballast, or starter, to initially move arc across tube

Fluorescent•The moving electrons collide with

mercury atoms in the tubes to make ultraviolet light▫Require appropriate disposal▫http://www.epa.gov/cfl/cflcleanup.html

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Fluorescent

LED

Light emitting diodes •Don't have filament

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LED

Light emitting diodes • Illuminated by

movement of electrons in semiconductor material

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LED

•Drivers regulate power to bulb•Often built into the fixture (like

fluorescent ballasts)

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Efficiency Comparison

•Incandescent: 10 lumens / watt•Fluorescent: 40 lumens / watt•LED: 90 lumens / watt

• Energy efficient

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Light Pollution Solutions

•Minimize interim light use with timers and motion detectors

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Light Pollution Solutions

•Shine lights down, not up

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•Fixtures that are fully shielded▫IDA Fixture Seal of Approval program

Light Pollution Solutions

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Shielded Luminaires

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How shielded lighting reduces glare• The image below is a test

site for fully shielded street lights. To the right; the same lights shown in comparison to the un-shielded existing lights.

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Fully shielded lighting at an airport

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International Dark Sky Initiative Lighting that is exempt from these

regulations:• Lighting in swimming pools and other water features governed by Article 680

of the National Electrical Code.• Exit signs and other illumination required by building codes.• Lighting for stairs and ramps, as required by the building code.• Signs are regulated by the sign code, but all sign lighting is recommended to

be fully shielded.• Holiday and temporary lighting (less than thirty days use in any one year).• Football, baseball, and softball field lighting; only with permit from the

authority recognizing that steps have been taken to minimize glare and light trespass, and utilize sensible curfews.

• Low voltage landscape lighting, but such lighting should be shielded in such a way as to eliminate glare and light trespass

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Cost of Lighting

Cost estimator•http://www.citytrf.net/costs_calculator.ht

m•Kilowatt-hour (kWh)

▫1000 watts used for an hour▫About $0.12 per kWh

•Running a 1000-watt appliance for 1 hour▫1 kWh

Cost of Lighting

•SCE&G▫$0.115 kWh

•Pond pump (340 watts) 0.33 kWh in an hour

•0.33 x 0.115 = $0.038 per hour•24 hours x 0.038 = $0.91 per day•30 days x 0.91 = $27.32

Cost of Lighting

•Small pond pump•0.01 kWh in 2 hours•0.005 kWh per hour•0.005 x $0.115 = $0.00058 per hour•X 24 hours = 0.014

Cost of Lighting

Landscape lights, 130W•0.13 kWh per hour•130W x $0.115 = $0.015•130W x 4 hours a night = $0.06•130W x 30 days = $1.80 a month

Cost of Lighting

•Christmas lights, 100W▫(1 strand)

•0.035 kHw per hour•100W x 0.115 = $0.004•100W x 10 strands = $0.04•100W x 6 hours = $0.24 a night•100W x 30 days = $7.20 a month

Cost of Lighting

•Refrigerator, 1.37 kWh per 16.5 hours•0.083 kWh per hour•$.0095 per hour•$0.23 per day•$6.87 per month

Cost of Lighting

•Computer station at home•1.81 kWh / 15 hours

•http://buildingdashboard.net/wakeforest/#/wakeforest/

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