Parking garages are prime candidates for energy-saving lighting because these spaces are large and the lights are often left on all the time – regardless of occupancy – especially on underground floors, although the USDOE estimates they operate an average of 18 hours/day. Parking garage lights differ from outdoor parking lights because they are lower wattage, need to be vibration resistant, and are mounted on walls and/or typically low ceilings where a low profile is essential so vehicles can pass under them. Vandal-resistant fixtures are often necessary. LEDs are penetrating this market; some manufacturers of multiple technology products are finding that LEDs account for 30% of their sales.

While heat is the enemy of LED technology, cold is its friend: LED performance is not degraded, and is sometimes better, in cold conditions. LED lighting for parking facilities has reached the point where the light output and efficacy meet or beat the traditional lighting sources of metal halide (MH), induction and high-pressure sodium (HPS) systems. LEDs, with a good fixture design, offer a more even distribution of light without the familiar “hot spots” created by other lights. Because of this, measured light levels can be reduced with LEDs in some facilities while still improving visibility. Fixtures may be parking garage-specific or low-bay fixtures.

LED technology can generate significant savings in parking facilities, indoors and out, over traditional technologies, in part because they can be controlled more easily with occupancy or daylighting sensors, so the lights are on only when needed. The directionality of the light can be used to good advantage, especially in facilities with one-way traffic flow, where glare can easily be controlled for drivers. The white light generated by LEDs makes it easier to identify vehicles by color than HPS systems. The long life should reduce maintenance costs as well.

In spite of all the benefits, choosing to use LED products in this application is not a “no brainer.” The specific site situation and products being considered must be carefully assessed. The speed with which LED technology is improving and the number of new products entering the market requires consumers to thoroughly research their options right before making a purchase.

Retrofit kits for existing luminaires are also available. Well-designed retrofit kits can deliver the same benefits of integral luminaires. Retrofit kits typically include a complete LED lighting system, including LED modules and/or arrays, optics, driver, and mounting hardware. Retrofit kits can be lower cost than integral luminaires, but not always as the price of integral luminaires continues to decline.  Retrofit kits allow reuse of existing housings, which can be of particular benefit for some applications. On the other hand, lumen maintenance, thermal management, light distribution, and physical mounting can be of concern for retrofit kits, as the design must allow for proper operation in a wide variety of housings. For reliable performance, utilize retrofit kits certified for compatibility with the specific make and model number of the existing street lights.

Traditionally, parking garages have used HPS, MH and, more recently, induction or linear fluorescent lighting. Induction, HPS and MH systems are typically left on all the time or used during business hours and controlled manually or by timers. Linear fluorescents offer easier switching than HPS or MH, which makes it possible to use controls such as occupancy or daylight sensors; however, many linear fluorescents are not controlled.

HPS is a long-lasting system, but their poor color rendering can make it difficult to identify vehicles and may contribute to a dingy feeling, adding to the perception that the area is less safe. Most people prefer white light that renders colors well so they can more confidently assess who is near them, what is going on around them, and can more easily identify their own vehicle.

Induction is an expensive “white light” option compared to MH, but is more affordable than early LED systems. Induction also offers a longer lamp life than the other choices – 100,000 hours for the lamps but about 60,000 hours for the generator (similar to a ballast) – so is especially useful for reducing maintenance. Until recently, induction lighting could not be dimmed.

Linear fluorescents use relatively large, low-profile fixtures, with multiple lamps per fixture, so a lamp failure does not create a completely dark area. They can be controlled easily, but are sensitive to very cold temperatures. The newer T8 fluorescent systems are much improved over old T12 technology in efficiency, lumen maintenance, lamp life and response to cold weather.

Federal energy efficiency standards (see http://www1.eere.energy.gov/buildings/appliance_standards/) are impacting which products will remain on the market, and codes are continuing to require less lighting power density (watts/square foot).

The U.S. Department of Energy (USDOE), through the Solid State Lighting (SSL) program’s CALiPER (Commercially Available LED Product Evaluation and Reporting) project, has results for various lighting products suitable for use in parking garages (Round 10). The GATEWAY Demonstration Program has case studies of many projects. One of these looks specifically at parking garage lighting: “LED Parking Garage Lighting: Providence Portland (OR) Medical Center in 2008,” and others focus on parking lot lighting. Like LED technology in general, products for this application continue to evolve, with lower costs, more light output, improved efficiency and more control options. A good general background of the technology can be found at the USDOE’s SSL website.

In 2010, LEDs made up 4.1% of parking garage lighting in place. In the 2007 report, Energy Savings Estimates of Light Emitting Diodes in Niche Lighting Applications, no LED installations were used in parking applications. Since then, a more recent volume of that report notes that “Garage lighting has led the transition to LED in the parking sector, with some garage lighting manufacturer’s noting nearly 30% of current sales are LEDs.”

First costs are still high, but prices are dropping. Life cycle costs should be used in analyzing the system.

Because LED availability, price and quality are improving so rapidly, many potential customers may wonder if “now” is the right time to buy. Is it worth waiting until next year to buy, when the available product will be higher quality, more efficient and cost less, or should consumers capture the savings available now? Given that the life expectancy of the products is measured in decades, jumping in at a high first cost can be seen as risky.

Unfamiliarity with the products and how to select them can be intimidating to potential owners. See References for some helpful resources. A test installation is the best way to determine whether a fixture will work in a specific application, and they can be quite expensive.

The Commercial Building Energy Alliances (CBEA) considered linear fluorescent, induction and LED in making their parking facility lighting specification. For white light, linear fluorescent is probably the most competitive and has the highest lumen maintenance, but is not necessarily the most popular technology. A good fluorescent system would not be a great candidate for a retrofit, but might still be a great choice for new construction. Pulse-start MH might be preferred where the installation is exposed to a wide temperature range. Induction lighting still offers a long life and more fixtures and control options have become available in the last few years, but LEDs are bringing stiff competition as prices come down. Linear fluorescent and MH will have higher maintenance costs than induction or LED. Old HPS, incandescent, probe-start MH, and T12 systems would all be excellent candidates to upgrade to LED.