Efficient Lighting for LEED Optimize Energy Performance

With the potential to gain between 16 and 20 points, this credit and category can contribute more toward your LEED certification than any other. This is for a reason, of course. USGBC wants to encourage design that has the most environmental impact, which energy savings surely does.

Points awarded may vary depending on the project type (i.e. if you choose option one of a whole building energy simulation), but it’s a worthwhile investment of time and resources.

Lighting Terminology and LEED

Among the many ways to improve the energy performance of a BD+C, ID+C or O+M project, the right choice of energy efficient lighting can have one of the most significant impacts. On average, lighting accounts for nearly 35% of electricity usage in commercial buildings.

While LED lighting often requires an increased upfront investment, the efficiency and resultant cost savings have continuously been shown to generate a positive return on investment (ROI) over time. When combined with automated occupancy sensors and photocells, the reduced lighting power can reach double-digit percentages.

When examining LED lighting options, here are some key terms to consider that are related to LEED credits.

• Lumens: Total quantity of light emitted by a light source. Learn more.
• Lighting Density: Required watts per square foot which varies according to occupancy rate and type of space.
• Color Rendering Index (CRI): A rating from 0-100 which assigns a value to a light source’s ability to produce color in objects. Optimal interior applications use a CRI of 80 or more.
• Correlated Color Temperature (CCT): Measured in Kelvin, this measures the light source’s color appearance. The higher the temperature, the bluer (cooler) the light will be. (Always test different temperatures to determine appropriate levels.) For instance, the warm light produced by a match flame might have a score of 1,700 whereas those blinding, white light Xenon headlamps on some cars might have a score of 6,200.
• Daylighting: Natural lighting provided by the sun (not to be confused with direct sunlight) is encouraged inside LEED buildings. This not only reduces lighting power needs, but when combined with views, introduces a connection between a building's occupants and the natural environment. Daylighting levels should always be considered when determining lighting needs. Many luminaires (fixtures) offer integrated photocells which can automatically dim lights in response to daylight shifts.

Remember, too, that ceiling lighting can creates an unappealing one-dimensional environment. Be sure to use multiple layers and a combination of direct/indirect lighting to create the most harmonious, natural space for occupants. To read more about the basics of layered lighting design, check out this straightforward post.

Of course, energy savings will work in any building, LEED certified or not. That's the beauty of green building, after all. So, when maximizing energy savings associated with energy efficient lighting, consider looking next to improvements that can be made in insulation, and HVAC for the highest returns.