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:
• An energy saving of 80%
can be achieved.
• Higher lighting levels are
attained.
BEKA states that LEDs are not
suited for use on high mast
lighting, since:
 Their use will not result in
energy saving
 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
24/48V
Power Supply
85-90
%
X
Current Source
350 mA
LEDs + PCBs
90-95
%
EFFICIENCY
=
72-86
%
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 %
= 93 lm/W available
x
90 %
x
95 %
Let us compare power:
High Mast 9*400W
HPS-T flood lights
LED (93) lm/W)
9*432W=3,888W
4,482W
(15% more)
9*55,000=495,000lm
416,882
Lumen / system efficacy
495,000/3,888=
127lm/W
93lm/W
Efficiency (PRL floodlight)
77 %
80 %
381,150lm
333,506
70 %
80 %
266,805
266,805
Luminaire power
Lumen (lamp)
Lumen floodlights
Utilization factor k (area lighting)
Lumen on the area
Let us compare power:
High Mast 9*400W
MH-T flood lights
LED (93) lm/W)
9*432W=3,888W
2,608W
(33% less)
9*32,000=288,000lm
242,550
Lumen / system efficacy
288,000/3,888=
74lm/W
93lm/W
Efficiency (PRL floodlight)
77 %
80 %
221,760lm
194,040
70 %
80 %
155,232
155,2325
Luminaire power
Lumen (lamp)
Lumen floodlights
Utilization factor k (area lighting)
Lumen on the area
Let us compare costs:
High Mast 9*400W
HPS-T flood lights
LED (93) lm/W)
9*432W=3,888W
4,482W
(15% more)
9*2600=
R23,400
R 189,000
(estimated)
Energy Costs/annum (0.5R/kW)
8,500
9,800
Saving per year
1,300
Luminaire power
Capital Cost Floodlights
Let us compare costs:
High Mast 9*400W
MH-T flood lights
Luminaire power
Capital Cost Floodlights
Energy Costs/annum (0.5R/kW)
Saving per year
LED (93) lm/W)
9*432W=3,888W
2,608W
(33% less)
9*3000=
R27,000
R 110,000
(estimated)
8,500
5,700
2,800
Verification by SABS:
Verification by SABS:
Comparison, based on Goldwyn’s claims:
High Mast 9*400W
HPS-T flood lights
Luminaire power
Lumen (lamp)
9*432W=3,888W
LED flood lights,
8*250W
2,000W
(50% less)
186,000
Lumen / system efficacy
9*55,000=495,000lm
495,000/3,888=
127lm/W
Efficiency (PRL floodlight)
77 %
80 %
381,150lm
70 %
148,800
80 %
266,805
199,040
(55% less)
3.17
1.35
(57% less)
Lumen floodlights
Utilization factor k (area lighting)
Lumen on the area
Actual Measurements (average)
93lm/W
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.
LED Efficacy
Utilisation coefficient
HID
White LED
100 lm/W
80 lm/W
70% utilization efficiency
50% utilization efficiency
Effective:
50 lm/W
Effective:
17
56 lm/W
BEKA LED Seminar 01 June 2010
Street lighting: Let us compare power:
Street light 250W MH-T LED (93) lm/W)
(92lm/W)
285W
145W
(49% less)
23000lm
13,600lm
Lumen / system efficacy
23,000/285=
80lm/W
93lm/W
Efficiency (PRL floodlight)
77 %
80 %
17,700lm
10,900
Utilization factor k (street
lighting)
43 %
70 %
Lumen on the road
7,600
7,600
Luminaire power
Lumen (lamp)
Lumen floodlights
Conclusion:
LED technology is well suited to achieve energy and cost
savings in many applications as of today!