Research Paper
2009 7th Grade Science Project
Compact Fluorescent vs. Incandescent Bulbs
By Chase McCord
Table of Contents:
- Introduction
- Materials and Methods
- Results
- Discussion
- Conclusion
- Acknowledgments
- References/Bibliography
Introduction:
My family has a pretty large electric bill, over
$250.00 per
month. I did this project because I heard Compact Fluorescent
(CFL) bulbs saved a lot of money and I
wanted to see if that was true and how much we might be able to save if
we switched.
Materials and Methods:
I built a test fixture out of some old strip lights
so I could do
side-by-side current measurements
of energy saving, Compact Fluorescent (CFL) bulbs versus standard,
household, Incandescent
bulbs. To make the test fixture safe for the science fare I added
an
isolation box so that I would never have to switch high voltage and so
the lights wouldn't be left on and waste electricity. This
allowed me to use a battery and a common doorbell switch to turn the
lights on and off. I used two analog amp meters to display the
current used by each set of bulbs; I used a digital amp meter to
get the most accurate current readings.
I measured the current usage for 40, 60, 75, 100,
and 150 Watt
incandescent bubs. I then measured CFL bulbs labeled as equal in
brightness.
CFL bulbs are sold with Wattage on the label being
the Watts used by an
incandescent bulb of similar brightness, but CFLs really use less power
than what is on the label. I measured them to see exactly how
much current the CFL used and exactly how they compared to the
incandescent bulbs. I measured the bulbs in sets of three to make
things quicker and to reduce the affects of any bulbs that had minor
aberrations in current flow.
I used an Excel spread sheet because there was a lot
of data and I
needed
to
find a way to keep it organized and avoid math mistakes. In this
experiment three of each type of bulb were measured, but only two 150
Watt bulbs were measured because they
are
very expensive and
then I adjusted my spreadsheet calculations to reflect this.
Three measurements were taken for each wattage because I wanted the
results
to be as accurate as possible. Those three measurements were then
averaged together and the average calculations were divided by
the number of bulbs
to get the average current per bulb. I measured the house voltage
and multiplied it by the amps to get the
Watts for each bulb.
I looked up some published electricity rates for
2008, but for this
project I wanted to use the rates my
family pays, so I used our November electric bill. I found the
number of kilowatt hours (kWh) we used
in November and the part of our bill for electric costs.
The electric costs were divided by the kWh to determine that our cost
for 1000 kWh
was $60.88. I used these figures to
calculate the cost of each type of bulb for one hour of use. By
looking at the cost of a one wattage of incandescent bulb for an hour
and
subtracting the cost of using an equivalent CFL bulb, I calculated the
savings per
hour. Then I counted all the bulbs in my house and then made an
estimate of how many bulbs stayed on for how many hours every
day. From
this I projected the savings per month for each type of bulb.
Materials:
- Quantity 3 each of 40, 60, 75, & 100 Watt Compact Florescent
(CFL) Bulbs, along with two 150 Watt CFL bulbs
- Quantity 3 each of 40, 60, 75, & 100 Watt incandescent bulbs,
along with two 150 Watt incandescent bulbs
- quantity 6 light fixtures
- Quantity 2 lighting strips
- quantity 3 amp meters (two analog, one digital)
- quantity 1 isolation box,
- quantity 1 low voltage momentary switch
- quantity 1 battery pack
- November Electric Bill
Results:
Table 1 represents my raw data collected with the
digital Amp meter.
Table 1
|
2009 Science Project Raw Data Jan 21
Three Bulb Array
Current Measurements
Bulb
Wattage
|
Test1
|
Test2 |
Test
3 |
40
INC
|
0.97
Amps
|
0.97
Amps |
0.97
Amps |
40
CFL
|
0.20
Amps |
0.21
Amps |
0.23
Amps |
| 60
INC |
1.51
Amps |
1.51
Amps |
1.51
Amps |
60
CFL
|
0.32
Amps |
0.36
Amps |
0.38
Amps |
| 75
INC |
1.89
Amps |
1.90
Amps |
1.89
Amps |
75CFL
|
0.40
Amps |
0.41
Amps |
0.42
Amps |
| 100
INC |
2.55
Amps
|
2.55
Amps |
2.55
Amps |
100
CFL
|
0.52
Amps |
0.53
Amps |
0.56
Amps |
150
INC*
|
2.58
Amps |
2.57
Amps |
2.58
Amps |
150
CFL*
|
0.61
Amps
|
0.62
Amps |
0.64
Amps |
* Two bulb array (due to cost of bulb) |
Table 2 below represents the averages of my three tests of
three bulbs:
Table #2, Calculations for Averages
|
Raw
|
Data, |
Three |
Bulb |
Arrays |
| Bulb |
Labeled |
Current (Amps) |
Current (Amps) |
Current (Amps) |
Current
Amps |
| Type |
Wattage |
Test 1 |
Test 2 |
Test 3 |
Average |
| Inc and. |
40 |
0.97 |
0.97 |
0.97 |
0.97 |
| CFL |
40 |
0.20 |
0.21 |
0.23 |
0.21 |
| Inc and. |
60 |
1.51 |
1.51 |
1.51 |
1.51 |
| CFL |
60 |
0.32 |
0.36 |
0.38 |
0.35 |
| Inc and. |
75 |
1.89 |
1.90 |
1.89 |
1.89 |
| CFL |
75 |
0.40 |
0.41 |
0.42 |
0.41 |
| Inc and. |
100 |
2.55 |
2.55 |
2.55 |
2.55 |
| CFL |
100 |
0.52 |
0.53 |
0.56 |
0.54 |
| Inc and. |
150 |
2.58 |
2.57 |
2.58 |
2.58 |
| CFL |
150 |
0.61 |
0.62 |
0.64 |
0.62 |
I wanted the data for one individual bulb, so I
divided by 3 to get the
current in amps per bulb. This is shown in table 3.
Table 3.
|
Data
Summary of Current/bulb |
| Bulb Wattage |
40 |
60 |
75 |
100 |
150 |
Inc and.. Current (Amps)
|
0.32 |
0.50 |
0.63 |
0.85 |
1.29 |
CFL current (Amps)
|
0.07 |
0.12 |
0.14 |
0.18 |
0.31 |
The bar chart below (chart #1) shows the comparison
of averages from
table 2. This is important because it clearly shows how much less
current is used by the CFL bulbs.
Chart #1
The household Voltage was measured at = 117.23 Volts
The formula for conversion of Amps to Watts: Current x Voltage =
Watts
| Table 4, Data Summary of Calculated Watts/Bulb |
| Bulb Wattage |
40 Watt |
60 |
75 |
100 |
150 |
| Inc and.. Watts |
37.90 |
59.01 |
73.99 |
99.65 |
151.03 |
| CFL Watts |
8.34 |
13.81 |
16.02 |
20.97 |
36.54 |
Once I knew the Watts per bulb I counted the bulbs
in our house.
Table 5
| Bulbs in Our House |
|
| 9 |
Kitchen |
|
| 5 |
Family Room |
| 1 |
Back Stairs |
| 1 |
Front entry way |
| 1 |
Side entry way |
| 1 |
Dining room |
| 4 |
Living Room |
| 10 |
2nd floor hallway |
| 5 |
Master BR |
| 13 |
Master bath |
| 1 |
Chase's BR |
| 7 |
Chase's bath |
| 4 |
Molly's BR |
| 3 |
Molly's bath |
| 3 |
Bonus Rom |
| 68 |
Total
Bulbs |
I calculated the cost and savings of the bulbs and
by subtracted, figured out the savings for each type of bulb. I
then used the number of bulbs in our house to predict the
savings. This is all in table 6.
Table 6
| Data
Summary of Calculated Cost/Bulb/Hr |
| Bulb Wattage |
40 |
60 |
75 |
100 |
150 |
| Inc and.. Costs/Hr. |
$0.002308 |
$0.003593 |
$0.004505 |
$0.006067 |
$0.009195 |
| CFL Costs/Hr. |
$0.000508 |
$0.000841 |
$0.000975 |
$0.001277 |
$0.002225 |
| CFL Savings/ Hr |
$0.001800 |
$0.002752 |
$0.003529 |
$0.004790 |
$0.006971 |
| Projected Savings per Month |
$15.45* |
$11.56* |
$14.82* |
$20.12* |
$29.28* |
| *(6
bulbs on 24 hrs/day {4,380 hrs/mo}, 10 bulbs on 14 hours/day for 30
days) |
| % of Nov Bill |
5.42% |
4.06% |
5.20% |
7.06% |
10.27% |
Discussion:
I compared the wattage calculated by my spread
sheet to the
wattage on the labels of
the incandescent bulbs, I found that my results were very close.
As a result, I believe my results for the CFL bulbs are really
accurate. I think it is a commonly held belief that CFL bulbs
save a lot of electricity and I certainly found this to be true.
However, I was certainly surprised at how little money this amounted to.
I am confident of my measurements, but to figure out
the cost per
month, I had to make some estimations and these could be off to some
extent.
I was surprised by how little savings there was if a
switch was made to
CFL bulbs, so I did some research and found that only 8.8% of the
electricity in a typical household is the result of lighting (see chart
2), so even if we switched to candles, we could only save around 9%.
Chart 2
Another factor to consider is the cost of bulbs. I
used 4-packs
of the
incandescent bulbs for about $0.80 or twenty cents per bulb. The
CFL bulbs cost a lot more (see table 7), but they are supposed to last
a lot longer. If the CFLs cost five to ten times as much, they're
going
to have to last five to ten times longer to be worthwhile.
Table
7
CFL and Incandescent Bulb Cost Comparison
Wattage
|
CFL
|
Incandescent
|
40
|
$1.72
|
$0.20
|
60
|
$1.72
|
$0.20 |
75
|
$3.44
|
$0.25 |
100
|
$3.22
|
$0.29
|
150
|
$9.97
|
$3.97
|
There are three other experiments I would like to do
before making up
my mind about Compact Fluorescent Bulbs. I want to test the
brightness; I used the label to pick bulbs that were equivalent to
incandescent, but those labels might not be so accurate. I also
want to test temperature; the CFL
bulbs seem to be cooler than incandescent bulbs and that could affect
the cost of cooling in the house. I would also test how long the
CFL bulbs last in our house compared to the incandescents.
Conclusions:
Compact Fluorescent bulbs save a lot of energy, but
because electricity
is so
cheap it doesn't save much money unless the lights are on for a long
time or electricity becomes more expensive. While the results
generally supported my
hypothesis, I still recommend my family switching to CFL bulbs. I
think they should do it
slowly, starting with lights that stay on a lot longer than the
rest.
Acknowledgments:
I would like to acknowledge the help of:
- Adapticom, Inc. for loaning me their digital meter.
- My dad for instructing me on the use of the isolation box to make
the project safe and save energy.
- Help from Mr. Tim Toombs for allowing me to explain my project to
him.
References/Bibliography:
Kirk, Karin B. "Energy Fact and Figures." Lifestyle Project. Skidmore
College. January 10, 2009.
<http://www.skidmore.edu/~jthomas/lifestyleproject/energyfacts.html>
Anonymous. "U.S. Household Electricity Report." July 14,
2005. Energy Information
Administration, Department of
Energy. January 12, 2009.
<http://www.eia.doe.gov/emeu/reps/enduse/er01_us.html>
Wang, Joanne. "A study on compact fluorescent lamps (CFL) and
incandescent lamps."
April 7, 2008. Rensselaer
Polytechnic Institute. January 12, 2009. <http://www.ewp.rpi.edu/hartford/~wangx2/SMRE/Term%20Project/Term%20Project%20Report.pdf>.
Anonymous, "ENG H191: Hands on Labs, AC Electricity." Ohio State
University. January 13, 2009.
<http://feh.osu.edu/Labs/ACElectricity/Lab%204%20WRITEUP%20-%20AC%20Electricity%20V4.0.pdf>
Jaden.
"Outlets,
Installing & Wiring." October 27, 2004. Alpharubicon.com.
January 13, 2009
<http://www.alpharubicon.com/altenergy/wiringjaden.htm>
Hodges, Laurent. "New Light on Energy Conservation." June 11,
1996. Iowa State University.
January 13, 2009.
<http://www.public.iastate.edu/~lhodges/compacts.htm>
Anonymous. "An Informative Guide To Compact Fluorescent
Lighting." University of Wisconsin.
January 14, 2009.
<http%3A%2F%2Fecow.engr.wisc.edu%2Fcgi-bin%2Fget%2Fme%2F349%2F
mitchell%2F2greenbuild%2Fcompact_fluorescent_lighting_guide.doc&ei=fVt_SaSWMNeitgek2qGWBQ&usg=
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Anonymous. "CFL Replacement
Worksheet: Cost-Benefit Analysis."
Eastern
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