Focus on Lighting First For Optimized Energy Performance

With the potential to gain between 16 and 20 points depending on the project type (if you choose "Option One" in this credit "Whole Building Energy Simulation"), EA Credit "Optimize Energy Performance" in LEED v4 is a worthwhile investment of time and resources.

And among the many ways to improve the energy performance of a new construction, major renovation or core and shell project, choosing more energy efficient lighting can have one of the most significant positive impacts.

Indeed, according to ENERGY STAR, on average, lighting accounts for nearly 35% of electricity usage in commercial buildings. While energy efficient lighting, such as LED lighting, can require an increased upfront investment, the increased efficiency and cost savings have consistently been shown to generate a significant return. Combine this with automated occupancy sensors, light measuring photocells and other controls and the reduction in lighting power can reach double-digit percentages.

Lighting Quality as Important as Efficiency

But while Optimize Energy Performance focuses on efficiency, LEED also emphasizes the indoor environment, which means considering the human needs associated with the workplace.

As such, energy efficiency is not the only thing that should be considered when designing interior lighting or approaching a commercial lighting retrofit. Indoor commercial lighting should not only be efficient, it should also be abundant and high quality. LEED v4 specifically addresses lighting quality in the Interior Lighting Credit in the Indoor Environmental Quality credit section, and includes a path for earning the credit titled "Option 2. Lighting Quality" which is good for one point.

If you're learning about lighting design and/or LEED, here are some key terms to consider.

Lumens: The measurement of brightness emitted by a light source. Light bulb manufacturers include information on lumens on packaging.

Illuminance: This is a measure of lumens on a surface. Often referred to as illuminance at a point, or light striking a surface, such as a table or desktop. Illuminance is often measured in footcandles per square foot (or in lux if square meters are being measured). In U.S. workplaces, minimum lighting levels, measured in footcandles, are recommended by occupational safety organizations such as OSHA.

Color Rendering Index (CRI): A rating of 0-100 of 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, CCT measures a light source’s color appearance. The higher the temperature, the bluer the light will be. (Always test different temperatures to determine appropriate levels.)

Daylighting: Natural lighting provided by the sun (not to be confused with direct sunlight) should always be considered when determining lighting needs. Photocells can automatically dim lights in response to daylight shifts. Increasing daylighting inside buildings can not only help with optimizing energy performance and efficiency, but also contribute to improved worker productivity.

Remember, too, that flat, ceiling only lighting can create an unappealing one-dimensional lighting effect. Be sure to consider using 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 lighting design, check out this straightforward post.

After maximizing the energy savings associated with energy efficient lighting, consider looking next to improvements that can be made in windows, infiltration, and HVAC for the highest returns.