Comparing Tubular LEDs and Tubular Fluorescents

First published: 23rd October 2014

Commercially-available energy-efficient lighting has progressed in the three years since I wrote, Comparing Tubular Fluorescents and the two years since I wrote, Comparing LED and Tungsten Halogen Lamps. This test compares a newly-available LED tubular replacement for a T8 fluorescent tube to an equivalent T5 conversion fitting.

Materials and Methods

The same equipment as described in Comparing Tubular Fluorescents was used but KWh meter measurements were not taken.

The luminaires and lamps tested were:

AbbreviationDescription
oldT5OSCxx T5/28W electronic ballast with old 28W T5 fluorescent tube. It was noted that some darkening of the tube was visible, so newT5 was added to the test.
newT5OSCxx T5/28W electronic ballast with new 28W T5 fluorescent tube.
LEDForcast LED-418D 6500K 18W tubular LED.

Results

Mains voltage224V
Distance from light fitting to PV cells45cm

Please refer to the table above for the abbreviation key.

LampLight intensity (PV cell output, mV)Current (Clamp meter, A)
oldT516.80.09
newT524.40.09
LED30.80.07

Analysis

LampLight output1Power (W)2Power Saving3Lighting efficiency4
oldT5100%200%100%
newT5145%200%145%
LED183%1622%236%

Notes:

From these figures, and adding the cost of the new equipment, it is possible to calculate the number of hours of operation before the savings have paid for the equipment. A one-for-one replacement is assumed, this results in a change in lighting levels, as noted in the Light output column of the first table above, but a change of 10% or less is probably not noticeable.

The cost for electricity is assumed to be HK$1.16

DescriptionCost (HK$)KWh to break-evenOperation hours to break-even
oldT5 (original situation)0
newT576.0
LED9077.617318

Sources of Error

There are many potential sources of error:

Conclusions and Areas for Further Study

Tubular LEDs are clearly now the replacement of choice when upgrading old T8 and T12 luminaires. They are probably the best choice when a T5 luminaire fails, but if a T5 tube fails, it is simpler to replace the tube. Bulk replacement of existing, working T5 luminaires is not recommended.


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