Identifying long-term strategies and the right technology to achieve maximum energy savings from lighting upgrades is no easy task. Especially for CA K-12 schools and community colleges struggling with energy expenses that rival the cost of books and supplies, and those schools hoping to maximize Proposition 39 funds, discerning selection is hugely important. To serve as a primer for making the most cost-effective decisions, the California Lighting Technology Center, at the University of California, Davis, has collaborated with its utility and industry partners to create a lighting retrofit guide for California schools.
The guide delineates four main areas in which lighting retrofits are particularly advantageous for elementary schools, middle schools, high schools and community colleges: converting older luminaries, harvesting daylighting, maximizing interior surface reflectance, and installing adaptive lighting strategies such as occupancy-based control systems. Here are some specific strategies for each category worth considering:
Improve Luminous Efficacy of Electric Light Sources
A great way to bring your lighting system up to speed is to convert older T8 fluorescent lighting to higher-efficacy light sources with dimming control. Worth considering—especially if you apply life cycle costing—are LEDs. Inherently controllable, LEDs can be combined in any shape to produce highly efficient illumination. Plus unlike CFLs, individual LEDs can be dimmed, resulting in a dynamic control of light, color and distribution.
For other lamps, the choice is clear: Convert all incandescent and CFL downlights to solid-state, LED technology. Their lumen-to-watt ratio makes them the leader in efficacy (a measure of brightness based on electricity use). Plus, the latest models of LEDs have fixed past glitches. With the correct fixture, LEDs reach full brightness instantly, with no buzzing or flickering.
In interior spaces, such as classrooms, gymnasiums and offices, where students, teachers and staff spend significant daytime hours, daylight harvesting is a savvy strategy not only to reduce use but also to improve quality. Existing windows and/or skylights can be used to supplement, or in lieu of, electric lighting, especially when electric lighting controls are incorporated that are able to dynamically adjust to complement daylight levels. It is, however, important to also install shading systems to avoid glare and heat gain from direct sunlight penetration.
Interior Surface Reflectance
There’s nothing like a strategic coat of paint to literally brighten up a space. Resurfacing walls, floors and ceilings (either with new paint or new panels or tiles) to have a high, diffuse surface reflectance makes interior spaces look brighter while equalizing brightness distributions and reducing glare.
Occupancy-Based Control Systems
Saving the most advantageous for last, the most dramatic opportunity to reduce lighting energy use in schools is typically in spaces without any type of occupancy-based control system. Examples of these are restrooms, hallways, utility spaces and outdoor lighting, including parking lots and building perimeters with wall packs. These areas are typically characterized by very long periods of operation with highly intermittent use patterns. Of course, occupancy-sensing controls in classrooms, offices, libraries, gymnasiums and other learning support spaces offer an additional layer of energy savings. In terms of corridors, stairwells and other secondary spaces, as well as all outdoor areas, the guide recommends occupancy-based, bilevel lighting.
The rewarding thing about these strategies is that they are no shot in the dark, so to speak. The guide points out that “Many of these strategies have proven to be so reliable and cost-effective that they are now required under California’s new 2013 Building Energy Efficiency Standards (Title 24, Part 6) for lighting, effective July 1, 2014.” That kind of supporting research helps remove the hesitation that can accompany major retrofits—and adds a cost-effective incentive for improving lighting in schools.