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Efficient Artificial and Site Lighting

Artificial lighting is lighting produced by electrical generation. Efficient artificial lighting produces the optimum lighting level for the task while using a minimum amount of electrical energy. In both residential and commercial buildings, electric lighting often accounts for a significant part of the building’s total energy bill.

Contents

1.Definition                                                
2. Use/Application
    a. Established Techniques
    b. Emerging Trends

3. Use an Integrated Approach

4. Resources

5. Associated Strategies

6. Case Studies

For office buildings, 30 percent of the energy used is for lighting—more than any other end use. Site lighting, required for pedestrian and vehicular safety, is also a significant consumer of energy in commercial occupancies. Residential occupancies present opportunities for efficiencies as well. According to the Environmental Protection Agency, if just one room in every U.S. home were switched to Energy Star qualified efficient lighting, carbon dioxide emissions would be reduced by over 1 trillion pounds over the life of the fixtures and bulbs. The primary goal for efficient interior artificial lighting is to provide the recommended lighting level for the task while using the least amount of energy.

Site lighting should direct the appropriate amount of light on illuminated surfaces without contributing to glare and light pollution. Site lighting should be sensitive to the natural environment and should not disturb the nocturnal habits of wildlife. For instance, lighting levels in rural areas and parks should be lower than those in suburban and urban areas. In the past, general illumination levels were high, but with a better understanding of lighting design, general or ambient lighting levels are now lower, with more emphasis on lighting the task, whether it be assembling electronic components, reading a book, or working at a desk in front of a computer.

In addition, the use of lighting controls has grown significantly, further reducing the energy consumed by artificial lighting by turning it off when not needed or reducing the lighting level to compensate for the availability of daylight. The Energy Policy Act of 2005, green building rating systems, and standards such as ASHRAE/IESNA 90.1 have provided guidance and incentives to incorporate efficient artificial lighting systems into buildings. ASHRAE/IESNA 90.1-20041 provides requirements for exterior lighting, including façades, architectural features, entrances, exits, loading docks, and illuminated canopies, as well as exterior building grounds provided through the building’s electrical service. The standard also has provisions for exterior lighting controls to turn off exterior lighting when sufficient daylight is available or when the lighting is not required during nighttime hours

The most efficient artificial lighting is used sparingly if at all. To achieve this optimize daylighting to minimize the amount of time the electric lighting is on. Light-colored walls, ceilings, and floors do a better job of reflecting light, including natural daylight, reducing the need for electric lighting. For residential applications, choose compact fluorescent lamps (CFLs) instead of incandescents for which 90 percent of energy is wasted as heat. Also, choose Energy Star fixtures for validated energy savings. Although CFLs cost more than incandescents, they last as much as 13 times longer and use 75 percent less energy. For commercial buildings, use high-efficiency fluorescent lamps and fixtures powered by electronic ballasts. Apply daylighting strategies and incorporate both daylighting and occupancy sensor controls into the design to minimize the time the electric lighting is on. Lower electric lighting loads can reduce the size of air-conditioning equipment needed to offset the heat generated by the lamps and ballasts. Lighting controls help save energy, meet green building ratings, and comply with energy codes. Today, the most efficient fluorescent lamps are T5 and T8. Both of these have a reasonably good color rendering index (CRI) of 75 to 98.

Efficient site lighting systems shine light on the area that needs to be lit without wasting energy or producing unusable light and glare. This is accomplished by using full cutoff luminaires that do not shine any light above the horizon line. Shorter poles and landscape lights produce light nearer to the ground, thus minimizing glare and light pollution. Tall lighting poles are to be used primarily for parking lots where multiple luminaries are mounted on a single pole to reduce the number of poles needed. Typically, full cutoff luminaires use flat glass lens rather than dropped refractors. Efficient site lighting systems must provide uniform illumination levels so that steps, curbs, and obstacles are not hidden in shadows. Design lighting controls into the project to turn off exterior lighting when the area is unoccupied overnight or after closing time.

ASHRAE/IESNA 90.1-20041 provides requirements for exterior lighting, including façades, architectural features, entrances, exits, loading docks, and illuminated canopies, as well as exterior building grounds provided through the building’s electrical service. The standard also has provisions for exterior lighting controls 

to turn off exterior lighting when sufficient daylight is available or when the lighting is not required during nighttime hours

Some artificial lighting strategies that can be easily applied to most projects include:

·    Avoiding incandescent lights

·    Using light-emitting diode (LED) exit signs

·    Reducing the general illumination level by employing task lighting

·    Incorporating daylighting and daylight controls into the lighting design

·    Using dimming or step ballasts for energy savings when full light level is not required

·    Matching the amount and quality of light to the function to  be performed

·    Switching lighting for perimeter zones to be separate from interior zones

·    Specifying higher efficiency light sources to produce more light with lower energy consumption

·    Specifying a CRI of 80 or higher for home and office environments

Using Lighting Design Tools

Lumen Designer (formerly Lumen-Micro) and LightScape Model are two of the leading lighting design tools available. Lumen Designer has a user-friendly interface that creates all levels of architectural spaces quickly and accurately. With LightScape, you can model your proposed lighting design to render its relative brightness. Both tools are CAD-compatible.

Lighting Power Density

IESNA has developed an interactive methodology for determining lighting power densities for both individual spaces and whole buildings. This methodology is the basis for the lighting power density numbers found in the ASHRAE/IESNA 90.1-2004

Standard. For example, using direct–indirect pendant-mounted fluorescent fixtures, uniformly generated artificial light with minimal glare can be achieved with as little as 0.8 watts per square foot.

Green Building Rating Tools

The U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED®) rating system has specific requirements for energy cost savings to achieve points in the “Optimize Energy Performance” category. Projects are required to achieve at least two points in this category. Additional points can be gained in the “Indoor Environmental Quality” category for incorporating daylighting into 75 percent of the spaces in a project. The GreenGlobes rating system by the Green Building Initiative also assigns points for energy efficiency based on meeting or exceeding the Environmental Protection Agency’s Target Finder performance target of 75 percent. An efficient artificial lighting system reduces the overall energy use in a building, which helps meet the LEED and GreenGlobes energy performance goals. For exterior applications the U.S. Green Building Council’s Leadership in Energy and Environmental Design (LEED®) rating system includes credit for eliminating light trespass from the building and site. The credit includes the requirement that exterior luminaires with more than 1,000 initial lamp lumens are shielded, and all luminaires with more than 3,500 initial lamp lumens meet the full cutoff IESNA Classification. LEED Sustainable Site Credit 8 has specific requirements to be met based on the specific zone, from wilderness and state parks to city centers. The requirement is not just for parking lots; it is also for landscape lighting and building façades. The GreenGlobes rating system from the Green Building Initiative also has points under site design related to site development for minimizing the obtrusive aspects of exterior lighting, including glare, light trespass, and sky glow.

Minimize Light Pollution

The International Dark Sky Association defines light pollution as any adverse effect of artificial light, including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste. Minimize light pollution by employing full cutoff luminaires that shine light downward, not overlighting. Light building façades from above, not below. Calculate the lumens needed to achieve the required average illuminance. Use low-

level landscape lighting on bollards to light walkways. Is exterior lighting needed? The most efficient lighting system is the one  that does not exist or is turned off when not needed.

Consider Solar-Powered Lighting

Solar-powered, battery-charging luminaires are available for street and area lighting. They are off the grid and ideal for remote areas where trenching for interconnecting power wiring can be harmful to the environment

Emerging Trends

The recent advancements in LED technology will lead to a revolution in lighting systems over the next decade or so. Although currently used in exit signs, traffic lights, and auto-mobile taillights, LED-based lighting fixtures may eventually replace fluorescent and high-intensity discharge (HID)  lighting systems for general illumination and task lighting.

Even in these somewhat limited applications, LEDs already save the country 9.6 terawatt-hours of electricity a year according to the U.S. Department of Energy. LEDs produce less heat and take longer to burn out and their color rendition is improving. LED lighting for building façades and streetlights is used by major retailers such as Wal-Mart to light building façades and signage. The added benefit of LEDs is their exceptionally long life that minimizes the labor needed to replace burned out lamps. Ann Arbor, Mich., will be the first U.S. city to convert all downtown streetlights to LED technology. Ann Arbor’s lighting conversion will reduce the city’s production of carbon dioxide and gases that contribute to global warming in an amount equal to taking 400 cars off the road for a year.

The use of lighting controls for exterior lighting is gaining acceptance. For buildings that are normally only occupied in the daytime, a significant amount of energy is wasted by lighting the parking lot all night. For safety reasons, parking lots should not be totally dark, but should maintain a low level of illumination. Also, HID lighting must have a warm-up time of up to several minutes; therefore, they cannot be turned off completely. Lighting controls are now available that sense when someone enters the parking lot and raise the lighting level to full brightness for a period of time. If no motion is detected after a preset time, the parking lot lights will return to the lower light level. Lowering sitelighting levels reduces light pollution and minimizes energy consumption.

A new way of thinking must be adopted in order to meet the goal of reducing carbon emissions associated with buildings.  Your solutions can begin by integrating four possible methods.  None works alone, and they are not all relevant in considering every strategy.  However, considering the following tactics is necessary:

• Reduce the overall energy use in your building.
  • Employing daylighting strategies, along with occupancy and daylight sensors, will reduce the overall energy use, allowing various building systems (i.e., HVAC) to be reduced in size and cost to make way for further energy-saving materials, designs, and technologies.
  • Specify energy-efficient equipment and technologies.
• Use renewable strategies and purchase green power.
  • Using energy-efficient lighting equipment with effective lighting controls can reduce a building’s overall energy load, require smaller and more cost-effective renewable strategies, and reduce emissions.
• Educate building owners, operators, and occupants.
  • Provide information on function and operations of installed technology so they can properly use lighting controls

There are many carbon-offset companies and organizations, several of which have unique approaches. Searching the Web is the easiest way to find the option that best suits your needs; verification that the offsets are used as stated is essential. The following list offers a diverse range of carbon-offsetting options:

• Energy Policy Act of 2005 (PDF 1.9 MB, 550 pgs)
• Federal Green Construction Guide for Specifiers 26 50 00 (16500) Lighting
• Whole Building Design Guide, Resource Pages, Electric Lighting Controls, David Nelson, AIA, David Nelson & Associates: www.wbdg.org/design/electriclighting.php
• ASHRAE/IESNA 90.1-2004, Energy Standard for Buildings, Except Low-Rise Residential Buildings

All 50to50 strategies relate to each other in some way. However, we recommend that you consider investigating these selected 50to50 strategies to assist you in gaining a deeper understanding.

• Building Orientation
• Daylighting
• Energy Modeling
• High Efficiency Equipment
• Life Cycle Assessment
• Open, Active, Daylit Spaces
• Smart Controls
• Walkable Communities
• Windows and Openings

• Garthwaite Center for Science & Art
• Global Ecology Research Center
• Government Canyon VIsitor Center

 Garthwaite Center for Science & Art
 Photo credit: Chuck Choi

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