Magazine

Lower Your Lighting Costs Save the Planet

Donald R. Monahan, P.E.

Politicians and the general public have increased their attention on global warming in recent years, and this enhanced awareness has resulted in new government- and utility-sponsored programs that provide rebates and tax incentives to increase energy efficiency and conserve energy.
Retrofitting your parking facility lighting system with more energy-efficient lighting can not only benefit from these incentive programs, but owners can realize a 40 percent savings or more in lighting operational costs. Payback periods are often less than four years.
This article discusses the energy conservation incentive programs that have evolved from the global warming issue and how best to implement energy conservation measures in your parking facility.

Energy Conservation Incentives
The National Energy Policy Act of 2005 (EPAct 2005) contains a variety of tax credits and deductions for businesses and consumers that are designed to encourage investment in energy-efficient commercial buildings. Lighting products and systems are ideally positioned for deployment using the deduction provision. EPAct 2005 allows a tax deduction of up to $1.80 per square foot where energy conservation measures reduce the total annual energy and power costs to less than 50 percent of the ASHRAE 90.1-2001 standard (includes interior lighting systems; heating, cooling, ventilation and hot water systems; and building envelopes). For lighting systems, the amount of the tax deduction is the lesser amount of $0.30 to $0.60 per square foot or the costs incurred or paid for the energy-efficient lighting system. The amount of the tax deduction is $0.30 per square foot for a 25 percent reduction in lighting power density from that required by ASHRAE 90.1-2001 to $0.60 per square foot for a 40 percent reduction, and prorated proportionately in between those values.
The ASHRAE 90.1 lighting power density requirement for parking garages is 0.3 watts per square foot. A system with a lighting power density of 0.18 watts per square foot qualifies for the maximum deduction of $0.60 per square foot. A system with a lighting power density of 0.225 watts per square foot qualifies for a deduction of $0.30 per square foot. The tax deduction is allowable in the year that the energy-efficient improvements are placed in service. New parking facilities and retrofit of existing parking facilities qualify for the deduction.
In addition, local and regional utility companies offer rebates for implementation of energy conservation measures. For example, Xcel Energy, based in Minneapolis, even offers funding of up to 75 percent of the cost of a Lighting Redesign Study. (Applications must be submitted between July 1, 2006, and March 31, 2007.) Additional rebates are offered on a per fixture basis. Go to the website for the Database of State Incentives for Renewable Energy (DSIRE) at http://www.dsireusa.org to find energy rebate programs in your state.

Energy-Efficient Lighting Design
Fluorescent light fixtures with high-frequency electronic ballasts are more energy-efficient than either metal halide or high-pressure sodium fixtures. An 8-foot-long fluorescent fixture with pairs of 32-watt T8 lamps in tandem or a 4-foot-long fluorescent fixture with two 54-watt T5HO (high output) lamps produce the equivalent maintained (design) lumens as does a 150-watt HPS fixture or 175-watt MH fixture (see Table 1) at 40 percent less wattage per fixture. A typical configuration with light fixtures at a 30-by-30-foot spacing in a parking facility will produce an average maintained illuminance of approximately 7 foot-candles, with a lighting power density of approximately 0.12 watts per square foot. This design would qualify for the full tax deduction under EPAct 2005, as well as any state or local utility rebates.
Fluorescent fixtures have not traditionally been used in cold climates as bare fluorescent lamps lose 50 percent of their light output at 32 degrees F. However, recent testing of enclosed fluorescent fixtures (vapor tight) indicates that the temperature inside the fixture may be 50 to 55 degrees higher than the outside ambient temperature. Therefore, enclosed fluorescent fixtures may be used in weather conditions down to 10 degrees F with less than 20 percent reduction in light output (see Figure 1).

Cost Savings
If the lighting system is operated 24 hours a day all year, then there are 8,760 total operating hours.
Table 2 indicates the annual operating cost at a national average of $0.10 per Kilowatt-hour (Kwh).
Therefore, there is a 47 percent savings to change from 175W MH fixtures to a fluorescent fixture with four T8 lamps, or a 44 percent savings to change from 175W MH fixtures to a fluorescent fixture with two T5HO lamps. Even compared with 150W HPS fixtures, the savings is 42 percent and 38 percent, respectively.
The retrofit cost on a recent project for the Albany (NY) Parking Authority was approximately $440 per fixture to replace the existing 175-watt MH fixtures on a one-for-one basis with an 8-foot fluorescent fixture with four T8 lamps. The utility cost in Albany has increased 25 percent in the last year, and is approximately $0.15 per Kwh this year. The annual operating cost for the 175W MH fixtures is then $273 per year versus $145 for the fluorescent fixtures, for a net savings of $128 per year per fixture. The payback period is then 3.4 years, exclusive of any tax incentives or rebates. The EPAct 2005 tax incentive does not apply to a tax-free municipal garage; however, rebates are available from the N.Y. State Energy Research and Development Authority, which will further reduce the payback period.

Summary
Retrofitting your parking facility lighting system from HID fixtures to fluorescent fixtures can save 40 percent or more on your lighting operational costs, exclusive of any lighting rebates and tax deduction incentives that are available from government- and utility-sponsored energy conservation programs. At the same time, you can feel good about reducing energy usage and reducing greenhouse gases.

Article Abstract from November, 2006




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