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Hallway lights energy use summary

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Hallway lights energy use summary First what assumptions did we make? All lights had the same wattage bulbs Number of hours lights were on during the day – PowerPoint PPT presentation

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Title: Hallway lights energy use summary


1
Hallway lights energy use summary
  • First what assumptions did we make?
  • All lights had the same wattage bulbs
  • Number of hours lights were on during the day
  • All bulbs were on all the time
  • All fixtures had the same number of bulbs in them
  • Electricity costs 0.11 per kilowatt hour

2
Hallway lights energy usage
  • Room KW /day yearly cost
  • TCCW 1 49.9 1,976
  • TCCW 2 78.6 3,156
  • TCCW 3 74.1 2,975
  • TCCW 4 66.6 2,672
  • Total for TCCW 10,779

3
Hallway lights energy usage
  • Room KW /day yearly cost
  • Snell B 14.0 562
  • Snell 1 64.7 2597
  • Snell 2 13.6 547
  • Snell 3 58.96 2367
  • Snell 4 19.5 781
  • Total for Snell 6,854
  • (3686.77)

4
Horse power
  • Arose as a result of the invention of the steam
    engine. People needed a way to compare the power
    of a steam engine to that of the horses it was
    replacing.
  • Confusing unit there are too many different
    definitions!

5
BTU
  • BTU British Thermal Units - an energy unit
  • the amount of heat required to raise the
    temperature of one pound of liquid water by one
    degree from 60 to 61Fahrenheit at a constant
    pressure of one atmosphere
  • Used in the power, steam generation, heating and
    air conditioning industries and the energy
    content of fuels.
  • However, BTU is often used as a unit of power,
    where BTU/hour is often abbreviated BTU.
  • So you need to watch the context!

6
Back to Watts..
  • A human climbing a flight of stairs is doing work
    at a rate of about 200 watts.
  • A typical household incandescent light bulb uses
    electrical energy at a rate of 25 to 100 watts,
    while compact fluorescent lights typically
    consume 5 to 30 watts.
  • A 100 Watt light bulb consumes energy at the rate
    of 100 joules/second.
  • After 1 hour, this light bulb uses 100 watt-hours
  • 1 kilowatt (kw) is 1000 Watts

7
Examples
  • In a certain room in your house, you use a 100 W
    light bulb. This light is on for 5 hours every
    day. How much energy does it use?
  • 1 W 1 J/s and there are 5hours x 60min/hour x
    60 sec/min 18,000s in 5 hours so the total
    energy used is 100 j/s 18000s 1.8 x 10 6 J.
  • Lets assume the same lighting level can be
    achieved using a 30 W compact florescent bulb.
    How much energy is used by the compact florescent
    bulb?

8
Examples
  • Total energy 30 j/s x 18000 s 5.4 x 105 j.
  • So how much energy is saved every day using the
    compact florescent bulb? Take the difference
    between the energy used by the two different
    light bulbs 1.8 x 10 6 j - 5.4 x 105 j 1.3
    x106 j.
  • Lets look at this in something you might be able
    to relate to better than joules---dollars!

9
Example continued
  • After 5 hours, our 100 W light bulb uses 500
    Watt-hours, or 0.5 Kwh. The 30 W bulb will use
    150 Watt hours or 0.15 Kwh.
  • Assume electricity costs 11 cents/Kwh (roughly
    the average cost in the US in October 2010). So
    it costs .5 KwH x 11 cents/Kwh 5.5 cents every
    day to run the 100 W light bulb and 0.15Kwh x 11
    cents 1.65 cents every day to run the compact
    florescent.

10
Example continued
  • So in a year, the 100 W light bulb costs you 5.5
    cents/day X 365 days/year 20.00 and the 30 W
    bulb costs costs you 1.65 cents/day x 365
    days/year 5.50.
  • Savings of 14.50/year per 100 W light bulb!
  • There are now 13 Watt LEDs that can replace 100 W
    light bulbs.
  • These would cost 2.61 per year. Thats a 17.39
    per year per bulb savings.

11
How do CF bulbs work?
  • made of glass tubes filled with gas and a small
    amount of mercury.
  • produce light when the mercury molecules are
    excited by electricity running between two
    electrodes in the base of the bulb.
  • mercury emits ultraviolet light, which in turn
    excites the tubes phosphor coating, emitting
    visible light.

12
Limitations of CF bulbs
  • Take longer to turn on
  • Do not work with dimmer switches
  • Contain mercury, a known toxic substance

13
Mercury in CFLB
  • 4-5 milligrams per bulb, about the size of a
    period.
  • Old mercury based thermometers contain about 500
    milligrams.
  • Should be disposed of carefully at recycling
    centers, not in the trash.
  • If broken, specific steps need to be followed to
    be safe, but you do not need to call a hazmat
    crew.

14
Is the government taking away your incandescent
light bulbs?
  • Provision in the Energy Independence and Security
    Act of 2007 signed in to law by president
    George Bush
  • Set energy efficiency standards for light bulbs
    that many incandescent light bulbs to not meet
    it does not ban current generation of light
    bulbs, simply sets energy efficiency standards
    for light bulbs sold and used in the US which
    will phase out use of the current generation of
    incandescent light bulbs.
  • Incandescent light bulbs currently exist that are
    affordable (2.99 for a two pack) and meet the
    new energy standards-so you dont have to buy the
    CFLB.
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