Consulting-Specifying Engineer - December 2008 - (Page 47)

P arking structures are significant users of electrical energy for lighting and can be a political hot-potato because they typically are illuminated 24 hours a day and, due to their open nature, are quite visible to the public. Due to the visibility and long operational hours, conservation of energy for lighting systems can contribute to both a savings in operating costs and a reduction of greenhouse gas emissions from the power plants that generate the power to operate these lighting systems. Another perk: tax deductions and rebates from local utilities for lighting retrofits. Conservation of energy for parking garage lighting systems involves the use of energy-efficient light sources and automated controls to turn off lights when they are not needed. Automatic controls to detect daylight contributions can turn off the lights on the perimeter of the garage or, if adequate daylighting penetrates the garage, turn them off entirely to save energy. Motion sensors may be used to turn the parking garage lights to full output when cars or people enter the garage and automatically turn off or turn down the lights when the garage is not occupied. Motion sensors are not practical for completely extinguishing metal halide or high-pressure sodium lamps because they take 10 to 20 minutes to restrike, but they may be used to dial down the light output by approximately 50% when the space is unoccupied. Photocells may be used for the top decks of This Grand Junction, Colo., parking structure boasts daylighting and 200 W metal halide lights. Photo: Walker Parking Consultants the parking garage to turn the upper garage lights on at dusk and off at dawn. Reducing the lights to 50% of their nominal lighting output when the facility is unoccupied could save 25% to 40% on lighting operational costs. For above-ground, open parking garages (20% of perimeter wall area is open at each level), lights near perimeter wall openings could turn off when there is adequate daylight infiltration. Computer calculations of daylight infiltration indicate that light fixtures within 30 ft of a perimeter wall opening could Reducing greenhouse gases According to the U.S. Climate Action Report (U.S. Dept. of State, May 2002), greenhouse gases are accumulating in the atmosphere as a result of human activities, so both politicians and the general public have become more aware of global warming issues. In 1999, greenhouse gas emissions were about 12% above emissions in 1990. Carbon dioxide accounts for 82% of greenhouse gas emissions, which is produced primarily as a byproduct of fossil fuel combustion in automobiles, factories, and power plants. A reduction of power consumption by parking garage lighting systems will contribute to a reduction of fossil fuel consumption in power plants, resulting in a smaller amount of greenhouse gases produced. Potential tax credits for retrofits The EPACT 2005 energy legislation enacted by Congress on Jan. 1, 2006, provides a tax deduction for lighting retrofits that reduce energy consumption by 25% to 40% of the maximum lighting power density indicated in the International Energy Conservation Code (IECC). The maximum lighting power density (LPD) for parking structure lighting is 0.3 W per sq ft. If the LPD is 0.225, the tax deduction is $0.30 per sq ft of floor area or the cost of the lighting installation, whichever is less. If the LPD is 0.18, the tax deduction is $0.60 per sq ft or the cost of the lighting installation, whichever is less. The tax deduction is prorated for LPD in between those values. The installation must be completed by Dec. 31, 2013 (the deadline recently was extended as part of the Emergency Economic Stabilization Act of 2008.) Consulting-Specifying Engineer • DECEMBER 2008 47

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Consulting-Specifying Engineer - December 2008 Contents Viewpoint News M/E Roundtable ARC Awards New Construction Gold New Construction Silver New Construction Bronze Renovation Gold Renovation Silver A Green Approach to Air Conditioning Systems Turning Down the Lights Case Study New Products Equipment Lifecycles Advertiser Index Green Space Gas Technology Pure Power Supplement

Consulting-Specifying Engineer - December 2008

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