By Jeff Crane, P.E., LEED® AP
Published in the October 2007 issue of Today’s Facility Manager
Do you have green fatigue? This syndrome describes a condition experienced by facility managers (fms) summarily accused of destroying the planet and irreparably damaging the Earth’s climate. [For more on Crane’s opinion of this subject, see “Disaster Cometh…Or Not!”, February 2007, page 10.]
With apocalyptic sermons courtesy of deceitful politicians and hypocritical celebrities (aided and abetted by crisis driven, sensationalist media types) it might be hard to find any fm who hasn’t experienced at least some degree of this syndrome.
If you know someone needing relief from green fatigue, this column might help. It summarizes a recent project in my facilities where green was associated with the color of money in addition to the trendy environmental adjective!
Background: A quantitative review of lighting work orders in several buildings confirmed we were overdue for a group re-lamping. We decided to explore numerous options before replacing several thousand fluorescent bulbs.
Note of clarification: Group re-lamping has nothing to do with smoking or street lights. In fact, the management of TFM, its advertisers, and columnists do not condone smoking (except when golfing), and they take a deliberately ambiguous position on street lights, especially the ones that might be associated with light pollution and public safety. Group re-lamping is the practice of replacing all light bulbs in a given area to maximize labor efficiencies proactively and minimize occupant inconvenience associated with replacing individual bulbs as they expire. Another benefit of group re-lamping is consistent lighting levels/appearance throughout a space.
Most buildings managed by my team have been retrofitted (or built new) with electronic ballasts and T-8 (32 watt, low mercury) fluorescent bulbs. We consider this a cost-effective and energy efficient strategy as lighting technology continues to evolve.
Because the electronic ballasts for these buildings were only five to seven years old, we decided that a complete fixture retrofit (to perhaps T-5 technology) would not be warranted, since we expect another five to seven years of service from existing ballasts. Instead, we focused our energy (pun intended) on bulb options.
Although we’ve been pleased with 32 watt, low mercury bulbs offered by several manufacturers, we investigated re-lamping with 28 watt or 25 watt bulbs to conserve energy. After reviewing specifications, speaking with an independent electrical engineer, and conducting a life cycle cost analysis, we selected a 28 watt bulb with extremely low mercury content.
The 28 watt bulb was more expensive than the 32 watt bulb, and we were initially concerned about reduced light levels that might be associated with lower watts. However, we were pleased to learn that the 28 watt bulb had better performance characteristics than our standard 32 watt bulb and that light level expectations should be very comparable. We were also pleased to learn that the 28 watt bulb we selected had one of the lowest mercury levels in the industry and longer expected service life than the 32 watt bulbs being replaced.
It’s beyond the scope of this column to discuss mercury’s role in fluorescent lighting and its environmental implications. For a comprehensive review of fluorescent lighting technology, see the following Wikipedia entry:http://en.wikipedia.org/wiki/Fluorescent_lamp. [Or read the TFM article, “Why Recycle Used Bulbs?” by Jennifer Dolin, August 2007, page 18.]
A reduction of four watts per bulb (12%) might seem like a minor efficiency improvement, but lighting represents a significant percentage of an office building’s electrical consumption. It’s also important to recognize the double benefit associated with lighting improvements, since reductions in lighting energy decrease the cooling load on HVAC systems.
Using our average electricity cost (in cents per kWh), we became convinced the energy savings and longer life associated with 28 watt bulbs would justify the cost premium (compared to the 32 watt bulb); we also calculated that the electricity savings over the life of the new bulbs would actually pay for the entire cost of re-lamping (including labor and bulb recycling fees).
In other words, this was a project that would conserve energy while completely paying for itself over the life of the new lamps. The cost analysis didn’t even include HVAC savings or productivity improvements for our staff (who won’t be replacing so many burned out bulbs each week).
At this point, you might be wondering why we went for the field goal (with a 28 watt bulb) instead of the touchdown (the 25 watt bulb). Did you really expect an October FM Frequency column without a football analogy? Specifications suggested unacceptable light level degradation by going from 32 watts to 25 watts, despite the improved performance characteristics. We decided that even a few complaints about reduced lighting levels could quickly consume energy savings if additional fixtures were necessary to restore light levels. We decided that in four to five years (when it’s time to re-lamp again), our ballasts will be at the end of their useful life and we’ll evaluate a variety of even better technologies at that time.
Crane is a mechanical engineer and regional property manager with Childress Klein Properties, a leading real estate developer and property management services provider in the Southeast
This article intentionally didn’t address bulb recycling regulations or specific manufacturers/products evaluated. If you are interested in sharing the results of your re-lamping analysis or discussing specific product references or calculations used in payback analysis, please send your thoughts to Crane. Past FM Frequency columns can be found online.
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Topic Tags: Childress Klein Properties