Thursday, 13 November 2008 21:18
Much has been made of the differences between T5 technology and T8 technology. As interest in energy saving technologies has grown and become popularized, these codes have come to designate levels of energy efficiency, instead of merely indicating lamp tube diameter.
Assumptions of Efficiency:
- T12 = old and inefficient
- T8 = higher efficiency
- T5 = highest efficiency
Although, these assumptions are generally true, it is important to look at the application and determine the cost benefit of T5 over T8 in order to determine if the increased efficiency of T5 justifies the substantial increase in initial and long term maintenance costs.
General Assumptions of Cost :
- T12 = lowest lamp, ballast and fixture cost
- T8 = approx. 20% more expensive than T12
- T5 = 3-4 times the cost of T8
Levels of Efficiency
Considering these general factors, it is obvious that T5 is the best. But, how much better? With all factors weighed equally, a general presumption can be made, that:
- a. T8 is 40% more efficient than T12.
- b. T5 is 51% more efficient than T12.
Yet, T5 in this environment is only 9% more efficient than T8. This would never justify the substantial increase in fixture, lamp and ballast costs.
Furthermore, if energy savings is an issue, you can often lower the light output by 9 or 10 percent in order to recover the efficiency without any real impact to the perceived light levels.
Conclusion:
The “bottom line” is that T5 is superior to T8 in that it creates more usable light. However, it is not a “game changing” technology in that its superiority renders T8 obsolete (as is the case with T12). Incentive program throughout the US pays the same incentives on T5’s as they do on T8’s.
Finally, the real game changer will be LED and organic LED technologies. These technologies will render both T5 and T8 obsolete in the future. However, these technologies have not arrived as viable alternative yet, and are not in the imminent horizon for fluorescent fixture applications. The actual life expectancy is not as good and reliable as the T8 and T5 technology, and the light quality output is still questionable, except for special applications such as grocery freezers, etc. For the mean time, T8 and T5 will continue to be the reliable, energy efficient choice for a multitude of general applications. The astute lighting designer will specify based on individual project demands, not by an allegiance to one technology.
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