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Are LEDs an efficient light source for high mast lighting?
by Johann Schleritzko
Are LEDs an efficient light source for high mast lighting?
Goldwyn Lighting claims, by converting existing high mast lighting to LED light sources:
BEKA states that LEDs are not suited for use on high mast
lighting, since:
• An energy saving of 80%
can be achieved.
Their use will not result in
energy saving
• Higher lighting levels are
attained.
To achieve the same lighting
levels, as their HPS equivalent,
capital costs would have to be
be 8-10 fold, without any energy
saving benefit.
LED system efficacy:
LED system efficacy =
LED efficacy x driver efficiency x optical efficiency x Thermal efficiency
Efficacy of light sources
Driver efficiency:
220/230 V ~ AC/DC Power Supply
24/48V Current Source
350 mA
LEDs + PCBs
EFFICIENCY
85-90
%
90-95
%
72-86
%
X =
Optical efficiency:
Optical efficiency of TIR optics:
85 % - 90 %
Additional cover glass
+ ~ 8 % losses due to Fresnel reflection
Thermal efficiency:
LED efficacies are specified at a junction temperature Tj = 25 °C
Realistic condition: Tj = 70 °C Efficacy ~ 90 %
70
LED system efficiency:
LED system efficacy =
LED efficacy x driver efficiency x optical efficiency x thermal efficiency
120 lm/W x 90 % x 90 % x 95 %
= 93 lm/W available
Luminaire power
Lumen ( lamp )
Lumen / system efficacy
Efficiency (PRL floodlight )
Lumen floodlights
Utilization factor k ( area lighting )
Lumen on the area
High Mast 9*400W
HPS-T flood lights
9*432W=3,888W
9*55,000=495,000lm
495,000/3,888=
127lm/W
77 %
381,150lm
70 %
266,805 266,805
80 %
333,506
80 %
93lm/W
416,882
4,482W
(15% more)
LED (93) lm/W)
Let us compare power:
Let us compare power:
High Mast 9*400W
MH-T flood lights
LED (93) lm/W)
Luminaire power 9*432W=3,888W 2,608W
(33% less)
Lumen (lamp) 9*32,000=288,000lm 242,550
Lumen / system efficacy 288,000/3,888=
74lm/W 93lm/W
Efficiency (PRL floodlight) 77 % 80 %
Lumen floodlights 221,760lm 194,040
Utilization factor k (area lighting) 70 % 80 %
Lumen on the area 155,232 155,2325
Let us compare costs:
High Mast 9*400W
HPS-T flood lights
LED (93) lm/W)
Luminaire power 9*432W=3,888W 4,482W
(15% more)
Capital Cost Floodlights 9*2600=
R23,400
R 189,000
(estimated)
Energy Costs/annum (0.5R/kW) 8,500 9,800
Saving per year 1,300
Let us compare costs:
High Mast 9*400W
MH-T flood lights
LED (93) lm/W)
Luminaire power 9*432W=3,888W 2,608W
(33% less)
Capital Cost Floodlights 9*3000=
R27,000
R 110,000
(estimated)
Energy Costs/annum (0.5R/kW) 8,500 5,700
Saving per year 2,800
Verification by SABS:
Verification by SABS:
Comparison, based on Goldwyn’s claims:
Luminaire power
Lumen ( lamp )
Lumen / system efficacy
Efficiency (PRL floodlight )
Lumen floodlights
Utilization factor k ( area lighting )
Lumen on the area
Actual Measurements ( average )
High Mast 9*400W
HPS-T flood lights
LED flood lights,
8*250W
9*432W=3,888W 2,000W
(50% less)
9*55,000=495,000lm 186,000
495,000/3,888=
127lm/W 93lm/W
77 % 80 %
381,150lm 148,800
70 % 80 %
266,805 199,040
(55% less)
3.17 1.35
(57% less)
1. The claims made by Goldwyn Lighting that:
• 80% energy saving can be achieved, and
• Resulting in higher lighting levels
are incorrect.
2. The LED technology is, based on today’s LED efficacy not
suited to achieve energy savings for High Mast lighting
installations.
3. We urge all serious lighting companies to refrain from
making misleading statements, which would harm the
markets long terms acceptance of LEDs.
17 BEKA LED Seminar 01 June 2010
LED Efficacy
HID 100 lm/W
White LED 80 lm/W
50% utilization efficiency 70% utilization efficiency
Effective: 50 lm/W Effective: 56 lm/W
Utilisation coefficient
Street lighting: Let us compare power:
Street light 250W MH-T
(92lm/W)
LED (93) lm/W)
Luminaire power 285W 145W
(49% less)
Lumen (lamp) 23000lm 13,600lm
Lumen / system efficacy 23,000/285=
80lm/W 93lm/W
Efficiency (PRL floodlight) 77 % 80 %
Lumen floodlights 17,700lm 10,900
Utilization factor k (street
lighting) 43 % 70 %
Lumen on the road 7,600 7,600
Conclusion:
LED technology is well suited to achieve energy and cost
savings in many applications as of today!
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