|
Light Efficiency
To find out how light
efficient the bulbs were their average luminescence (obtained through a lux
reading taken over five minutes 1m from the bulb) was divided by how much
power they use to produce that luminescence. The cost efficiency was also
taken into account when calculating the overall result. This is a major part
of the bulbs viability so when discussing which is the better bulb this had a
big impact.
|
|
Philips
20W
Tornado
|
Ecobulb Brand 20W
|
Elite
20W
|
Switch
20W
|
Philips
100W
|
|
Average
Luminosity
|
1367.8
|
1380.7
|
1235
|
1460.7
|
1289.3
|
|
Watts
|
20.5
|
17.5
|
21.9
|
31.5
|
84.9
|
|
Light Efficiency (lumens/watt)
|
66.7
|
78.8
|
56.3
|
46.5
|
15.2
|
Cost Efficiency
To find
the cost efficiency of the bulbs, the cost to buy and run each bulb for its
life length was compared with the cost to buy and run the 100W incandescent
bulb for the same length of time. The calculations were done using the following
standard information: *The average cost of power quoted by the bulb boxes is
20c/kWhr ($0.2/kWhr) (you pay 20c per hour for every kW of power you use) *CFLs use 0.02kW of power.
The cost to run a bulb over
its life length is calculated by:
($0.2 x 0.02kW x bulb life
length x bulb purchase price)
|
|
Philips 20W Tornado
|
Ecobulb Brand
20W
|
Elite 20W Spiral
|
Switch 20W
|
|
Cost to run over life length
|
$29.79
|
$43.98
|
$35.65
|
$44.96
|
|
Equivalent cost to run 100W bulbs for same time length
|
$126.06
|
$210.10
|
$168.08
|
$210.10
|
|
Savings
|
$96.27
|
$166.12
|
$132.43
|
$165.12
|
|
