2014年10月28日星期二

LED Lighting for Parking Garages: Improving Safety and Saving Energy

By now, it may be safe to say that most people who think about lighting in some professional capacity, whether as a store owner, lighting designer, architect, contractor or something else, have been exposed to the general idea that LED lighting is more energy efficient and more cost effective than most alternative types of lighting. Large retailers like IKEA have made the news by announcing they are converting all their stores to LED lighting by 2016 and becoming the first US home furnishing retailer to sell only LED bulbs and lamps*. High-profile cultural institutions like the Louvre Museum in Paris have made the switch to LED. Municipal governments all over North America have been converting their street lighting to buy led high bay lamps in order to take advantage of cost-cutting benefits.

The humble underground parking garage, so important to building management, is a large consumer of expensive energy. Lights are on 24 hours a day for safety. Savvy building managers and property managers are turning to energy-efficient LED lighting, not only to save energy, but to brighten up the environment for safety.

In Toronto, according to the group LightSavers, there are about one-quarter of a million parking garage lighting fixtures burning around the clock, seven days a week, consuming enough energy to power about 20,000 homes. LightSavers, an initiative of the Toronto Atmospheric Fund, has shown in trials that electricity used in that garage lighting can be cut by 50 per cent by switching to LED lighting and by more than 70 per cent when smart lighting controls, such as occupancy sensors, are used as well.

Energy Savings Alone is Not Enough in the Underground Garage

There are many things to consider besides cost effectiveness when lighting a garage: technology, safety, light levels, ease of maintenance. (A good summary discussion of the subject of LED lighting for parking garage can be found here.)

There are many examples of parking authorities all over North America looking to LED lighting as a replacement for the High Pressure Sodium lights commonly used. In 2011, the City of Toronto Community Housing Corporation (TCHC) replaced 140 HPS garage lights with 55W LEDs with built-in occupancy sensor for bi-level dimming—the lights automatically dim when no one is in the area. The switch to LED resulted in an energy consumption reduction of 70 per cent while illuminance exceeded required Municipal Code levels.

The problem of the missing T8 replacement

Until now, though, there has been a large gray area in the emerging LED picture: the need for a reliable, bright, easy-to-install, high-performance LED T8 tube bulb to replace the old standby fluorescent tubes. The market for such a replacement bulb is vast, the size of the market demonstrating the need. According to the US Department of Energy (DOE), there were more than 1 billion fluorescent lights installed throughout North America as of 2010. Only about 1 million—less than 0.1 per cent—had been replaced with LED equivalents at that time.

What’s the problem? Again, turning to the DOE we find that the T8 market is fragmented, because of “blurry” lines between the different LED products that are available and the “substantial variation” among products. Different wiring configurations, luminous intensity distribution, and physical appearance are some of the differences that contribute to the products’ lack of consistency. Lack of consistency makes it difficult for specifiers and for facility managers alike.

New T8 products are meeting the need

In spite of the market confusion, a 2012 led high bay light for sale trial that involved lighting designers, engineers and facility managers found that “dedicated LED troffers are ready to compete with fluorescent troffers in terms of efficacy (lumens per watt) and in many lighting quality issues such as glare, light distribution, visual appearance and color quality.” The LED products in the Caliper test performed “as well as or better than” the fluorescent products. The highest-performing LED T8 lamps had lumen output of 76.5 lumens per watt, compared to a maximum 62.1 from the T8 fluorescent benchmark. Our own experience shows that in 2014, quality LED T8 lamps can now reach up to 100 or 105 lumens per watt, a further improvement.

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