to halogen or incandescent. CMH’s color and quality of light is comparable to halogen, but it consumes about 20 percent of the energy used by standard halogen lamps. The major downside of CMH is its warm-up time (about five minutes or so) and cost. In addition, CMH is not dimmable, so residential applications are limited to exterior lighting. Therefore, major markets for CMH are retail and other applications traditionally lighted with halogen. Light Emitting Diodes — LEDs are not the savior of the lighting industry. We all tend to be intoxicated by the apparent low energy consumption and extremely long rated life. These sources are great for applications requiring low lighting levels or direct view products. In addition, LEDs are a solid option for step or aisle lighting, cove lighting, display lighting, and some task lighting. LEDs are also appropriate for signage, special effect lighting (including color changing requirements), and many direct view applications (substituting for neon, for example). Along with selection of lighting sources, architects must also specify lighting controls, which in today’s projects occupy a strange place. All energy codes require lighting controls, but few give credit toward meeting the wattage limits. Energy codes may be turning toward a time when the additional energy savings of lighting control devices may actually help in achieving the lower wattage densities of codes. Tr y to avoid any lighting product programmed to automatically turn lights on unless it meets a specific functional requirement. For example, program any office lighting to switch on manually. This allows the user to leave lights off, if desired. This basic approach saves energy. Match light source with control technology, which includes: • Full-range dimming available in incandescent, halogen (including IR), linear fluorescent, and CFL sources.
• Limited-range dimming (down to 5 percent light output) available in linear fluorescent, some LEDs, and CFL sources. • Limited-range dimming (down to 30 percent intensity) available in metal halide. • Dual-level switching ballasts available for some fluorescent and metal halide sources. Some fluorescent ballasts are being produced with integrated control intelligence for dimming the lamps they power. Onboard intelligence allows motion sensors, daylight controls, and local override controls to be wired directly to the ballast using low-voltage cable. This technology appears to be the future of fluorescent lighting controls. Right size your lighting solutions and don’t be too quick to embrace new technology unless it meets a specific need on your project. To increase the success of your lighting design solutions, decisions should be integrated into the design phases. This begins with predesign/programming phase of the project. The lighting solution with the smallest carbon footprint is lighting you don’t install. If you avoid extraneous lighting hardware, lighting does not need to be installed, powered, or maintained. Charles Thompson, AIA, is president of Archillume Lighting Design in Austin.
Code Watch Codes are popping up in an increasing number of communities interested in reducing light pollution (uplighting) and light trespass (shining light across a property line). Limiting both of these offensive lighting concerns is admirable, but some of the local codes are troublesome. However, losing these fixtures and lighting techniques hampers the architect’s ability to create vibrant exterior spaces where people like to visit. Some local codes eliminate all uplight (used for building accent lighting, landscape lighting, and sign lighting) and further require all exterior lighting to be IESNA “full cut off.” This eliminates building accent uplighting, all forms of ground mounted fixtures, all adjustable fixtures, and most decorative fixtures. More appropriate regulation would relax the restrictions on light pollution and allow limited amounts of uplight while requiring the uplight to be turned off after business hours. Also, light trespass should be eliminated, but in a measurable manner. In all cases, lighting restrictions should be measurable. Lighting to meet subjective limits for light pollution/trespass will always be difficult to design and the legislation will be difficult to enforce.
(left) The exhibit space of Government Canyon by Lake/ Flato Architects utilizes low wattage, adjustable halogen accent lights for primary lighting of vertical surfaces. Fluorescent uplight on the ceiling provides soft-fill light for the interior wood ceiling. (right) The Austin Convention Center Parking Garage by Barnes Gromatzky Kosarek Architects uses compact fluorescent, linear fluorescent, metal halide, and LED direct view products.
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