(Chin-Woo Yi)
†iD
(Seong-Kuk Hur)
1iD
-
(Vice president, SekiHi-tech Co.,Ltd., Korea)
Copyright © The Korean Institute of Illuminating and Electrical Engineers(KIIEE)
Key words
Economical efficiency, Fluorescent lamps, Incandescent lamps, Interior lighting, Lamp efficacy, LED lamps
1. Introduction
Today, various types of light sources such as incandescent type compact fluorescent
lamps, FPL, straight fluorescent lamps, incandescent lamps, halogen lamps, and LED
lamps are used for indoor lighting. Therefore, it is necessary to compare the economic
efficiency of using various lamps. And the characteristics of a lamp, including its
price, change over time, and so the economic efficiency of the light sources also
changes over time.
In this paper, we investigate the changes in lamp characteristics between 2013 and
2024 to examine the changes in economic efficiency by light source[1]. The 2013 data is from LOWE'S at Orlando Florida, USA and the 2024 data is from Home
Depot at Chicago Illinois, USA.
Since there are various factors in the economic evaluation of lighting, economic benefit
can not be determined by just one or two variables. We evaluated the economical efficiency
of the indoor lighting sources considering lamp light output, lamp price, lamp replacement
cost, lamp lifetime, lamp input power and electricity charge. And when using a ballast
the cost related to the ballast is added.
2. Research contents
This study considers various indoor light sources, including incandescent type compact
fluorescent lamps(IL type CFL), FPL type compact fluorescent lamps(FPL), linear fluorescent
lamps(linear FL), incan- descent lamps(IL), halogen lamps(halogen) and LED lamps(LED).
The power consumption range of the lamps is 3(LED lamp) to 300(incandescent lamp)
W. And light output of the lamps ranges from 150(incandescent lamp) to 8,800(inear
fluorescent lamp) lm. The lifetime range is between 750(incandescent lamp) and 50,000
(lLED lamp) hours. But FPL type compact fluorescent lamps have no lifetime data. The
color temperature range of the lamps is 2,700(FPL type compact fluorescent lamp, incandescent
lamps, halogen lamp) to 6,500(FPL type compact fluorescent lamp, linear fluorescent
lamp, LED lamp) K. Most lamps do not indicate their color rendering indexes. The
color rendering indexes are marked as 62～90 only linear fluorescent lamp. And the
average price is the cheapest for an incandescent lamp at 2.49 dollars, and the linear
fluorescent lamp and LED lamp is the most expensive at 17.49 dollars. But 10 years
ago, the price of an incandescent lamp was 75 cents, and the price of an LED lamp
was 100 dollars.
Table 1 shows the characteristics of the lamps investigated.
The Changes in Economical Efficiency of Indoor Light Sources Over the Past Decade
Table 1. Characteristics of the investigated lamps (2024)
|
Lamp type
|
Power consumption
[W]
|
Light output [lm]
|
Lifetime
[hour]
|
Color temperature
[K]
|
Color rendering
index
|
Price
[$]
|
|
IL type CFL
|
65
|
-
|
10,000
|
-
|
-
|
14.88
|
|
FPL
|
7~27
|
-
|
-
|
2,700~6,500
|
-
|
4.97~12.47
|
|
Linear FL
|
13~110
|
1,075~8,800
|
7,000~35,000
|
3,000~6,500
|
59~90
|
3.12~17.49
|
|
IL
|
20~300
|
150~5,870
|
750~2,000
|
2,700
|
-
|
2.49~9.47
|
|
Halogen
|
35~50
|
400~750
|
2,000
|
2,700~3,000
|
-
|
7.97~9.97
|
|
LED
|
3~40
|
250~5,000
|
10,000~50,000
|
3,000~6,500
|
-
|
2.50~17.49
|
3. Economic comparison
Several methods are available for evaluating economic efficiency, including the initial
cost method, payback period method, investment interest rate method, internal interest
rate method, and life cycle cost method[2].
The cost of replacement was calculated as $1.35/ lamp and $4.05/ballast, and the electricity
charge was calculated as $0.15/kWh. The cost was calculated by applying an inflation
rate of 34.9% between 2013 and 2024[3].
In the case of using ballasts, the ballast price is calculated as $15.97/unit, and
the ballast power consumption is assumed to be 10% of the lamp power. Ballast lifetime
is assumed as 3 years.
For light sources that don’t use a ballast, when ignoring depreciation, the lighting
cost equation which uses simplified and redefined parameters can be expressed as[4-6]:
Where U = unit lighting cost of lamp [$ / 106lm․h]
Q = lamp light output [lm]
P = lamp price [$]
h = lamp replacement cost [$]
L = lamp lifetime [hour]
W = lamp input power [kW]
R = electricity charge [$/kWh]
The cost of lighting apparatus using ballasts can be expressed as[4-6]:
Where U = unit lighting cost of lamp [$/106lm․h]
Q = lamp light output [lm]
P = lamp price [$]
h = lamp replacement cost [$]
L = lamp lifetime [hour]
W = lamp input power [kW]
R = electricity charge [$ / kWh]
P'= ballast price [$]
h'= ballast replacement cost [$]
L'= ballast lifetime [hour]
W'= ballast input power [kW]
In this paper, the lifetime is calculated based on 3hours a day. In this case, the
lifetime means expec- tancy lifetime. And the light sources that can be compared from
the data in 2013 and 2024 were selected, 32, 40, and 75W for linear fluorescent lamps,
25, 40, and 200W for incandescent lamps, and 13 and 14W for LED lamps.
Table 2 shows the unit lighting cost required to use the 106lm of lamps for 1 hour using
equations (1) and (2). Looking at the unit lighting cost over a 10-year period, linear fluorescent lamps
increased by 149.1(32W)∼156(75W)% and incandescent lamps increased by 128.2(32W)∼176.2(40W)%.
On the other hand, LED lamps decreased by 62.1(14W)∼56.9(13W)%. The results of Table 2 are shown in Fig. 1.
And Table 3 shows the changes of the efficacy and light output per dollar of investigated lamps
over the past 10 years. Looking at the efficacy, for linear fluorescent lamps, there
is almost no change 96.8(32W)∼100(75W)% and for incandescent lamps, it was found
that increased 120.5(32W)% and de- creased 85.3(25W)%, and there was almost no change
for 200W. On the other hand, LED lamps increased significantly by 213.5 (13W)∼269.9(24W)%.
Looking at the light output per dollar, for linear fluorescent lamps, excluding 75W
lamp, 32W lamp decreased by 78.1% and 40W lamp decreased by 43.4% and for incandescent
lamps, it was found that decreased significantly 28.3(40W)∼64.5(200W)%. On the other
hand, LED lamps increased significantly by 223.4 (13W)∼292.5(14W)%.
During this period, the prices of linear fluorescent lamps and incandescent lamps
increased but their efficacy remained the same, while the prices of LEDs decreased
while their efficacy increased. The changes in efficacy over the past 10 years are
shown in Fig. 2.
Fig. 1. Unit lighting costs changes over 10 years
Fig. 2. Efficacy changes past 10 years
Table 2. Unit lighting costs of various lamps per 106lm․h
|
Lamp type
|
Power[W]
|
Efficacy[lm/W]
|
Light output per dollar[lm/$]
|
|
2013
|
2024
|
ratio[%]
|
2013
|
2024
|
ratio[%]
|
|
Linear FL
|
32
|
84.5
|
81.8
|
96.8
|
724.4
|
565.4
|
78.1
|
|
40
|
62.9
|
62.3
|
99.0
|
981.7
|
425.6
|
43.4
|
|
75
|
63.8
|
63.8
|
100.0
|
289.9
|
290.3
|
100.1
|
|
IL
|
25
|
7.3
|
8.8
|
120.5
|
105.6
|
63.1
|
59.8
|
|
40
|
9.5
|
8.1
|
85.3
|
304.6
|
86.1
|
28.3
|
|
200
|
17
|
16.5
|
97.1
|
1,146.5
|
739.4
|
64.5
|
|
LED
|
13
|
56.9
|
121.5
|
213.5
|
23.6
|
223.4
|
946.6
|
|
14
|
57.1
|
144.5
|
253.1
|
32
|
292.5
|
914.1
|
|
24
|
54.2
|
145.8
|
269.0
|
34.2
|
233.6
|
683.0
|
Table 3. The efficacy and light output per dollar changes of lamps
|
Lamp type
|
Power
[W]
|
Unit cost [$/106lm]
|
|
2013
|
2024
|
ratio [%]
|
|
Linear FL
|
32
|
1.69
|
2.52
|
149.1
|
|
40
|
2.17
|
3.29
|
151.6
|
|
75
|
2.07
|
3.23
|
156.0
|
|
IL
|
25
|
25.58
|
32.8
|
128.2
|
|
40
|
16.91
|
29.8
|
176.2
|
|
200
|
8.02
|
11.4
|
142.1
|
|
LED
|
13
|
3.69
|
2.1
|
56.9
|
|
14
|
3.22
|
2
|
62.1
|
4. Conclusion
In order to examine the economical efficiency of the light sources for indoor, the
unit lighting cost of lamp was calculated and it was found that in 2013, the order
was linear fluorescent lamps, LED lamps, and incandescent lamps, but in 2024, the
order was LED lamps, linear fluorescent lamps, and incandescent lamps, with LED lamps
beating out fluorescent lamps to become the most economical light source.
Using the 14W LED lamp as a reference, it was found that the cost of the 32W linear
fluorescent lamp is 1.3times, that of the 40 and 75W linear fluorescent lamp is 1.6times,
that of the 25W incandescent lamp is 16.4times, that of the 40W incandescent lamp
is 14.9times, and that of the 200W incandescent lamp is 5.7times.
Comparing the efficacy of lamps, the order was linear fluorescent lamp, LED lamp,
and incandescent lamp in 2013, but in 2024, LED lamp increases by about 2.5times and
other light sources remain unchanged, making LED the highest light source among them.
The current the peak efficacy of the LED lamps reaches up to 145.8lm/W in a 24W lamp.
Light output decreased by 43∼78% for linear fluorescent lamp and 28∼65% except for
75W, for incandescent lamp, but increased significantly by 680∼950% for LED lamps
over the past 10 years.
When comparing prices for 10 years from 2013 to 2024, linear fluorescent lamps increased
by 191% for 32W, 267% for 40W, incandescent lamps increased by 118% for 25W, 180%
for 40W, and 151% for 200 W, but LED lamps decreased by 22% for 13W and 17% for 14W.
During this period, the prices of linear fluorescent lamps and incandescent lamps
increased but their efficacy remained constant, while the prices of LEDs fell sharply
while their efficacy increased significantly. These are the decisive reasons why LED
lamp has become the most economical light source.
References
C. Yi and S. Hur, “The comparison of the economical efficiency of indoor light sources,”
Journal of KIIEE, vol. 32, no. 9, pp. 1-4, 2018.
W. Jang, et al., “New principles of lighting environment,” Moonoongdang, pp. 394-395,
2008.
Coinnews Media Group LLC, “US inflation calculator,” https://usinflationcalculator.com/
(Accessed 12 Feb. 2025)
Illumination Engineering Society of North America, “IES Lighting Ready Reference.”
p. 153, 1985.
C. Chee, “New illumination engineering,” Moonoongdang, p. 182, 1982.
C. Yi, “The comparison of the economical efficiency of light sources for a tunnel
lighting,” Journal of KIIEE, vol. 25, no. 2, p. 40, 2011.
Biography
He received his Ph.D.(1990), M.S.(1987), and B.S.(1984) degrees in Electrical Engineering
from Seoul National University, Korea. He is now a professor at Hoseo University,
Korea. His research interests include light sources and lighting design.
He completed his Ph.D. in Electrical Engineering at Heseo University(2013). received
a master’s degree in Material engineering at the Seoul Graduate School of Industrial
Science(2005), received a bachelor’s degree in Electrical engineering at Sungkyunkwan
University. He is currently serving as vice president of SekiHi-tech Co.,Ltd. His
research interests are lighting application and lighting design.