Outdoor Lighting Efficiency: How CA K-12 Schools Can Comply with Title 24
Keeping up with California’s stringent set of standards for school lighting-with its very specific set of requirements-means pushing an institution’s lighting infrastructure to achieve maximum efficiency. The report, “Lighting Retrofit Strategies for California Schools,” out of UC Davis, provides a detailed guide of the best solutions for common K-12 Proposition 39 outdoor lighting efficiency strategies.
The report says the latest Title 24, Part 6 standards require that all outdoor lighting be equipped with automatic scheduling controls in addition to photosensors (or astronomical time switches). Outdoor luminaires mounted up to 24 feet above the ground, such as parking lot pole lights, must also be equipped with motion sensors or another type of lighting control system that will automatically reduce lighting power 40 to 80 percent when areas are unoccupied. The four primary strategies for outdoor lighting savings are to retrofit with bi-level LED or induction light sources or luminaires; install sensor-based occupancy/vacancy controls; incorporate automatic scheduling controls; and include photosensors or astronomical time-switch controls.
In general, there are three main types of K-12 Proposition 39 compliant outdoor lighting: wall packs on exterior walls, pole-mounted high-intensity discharge (HID) in parking lots and canopy lighting configurations for parking areas and pathways. One of the best ways to achieve maximum savings is to integrate adaptive controls to reduce wasted light during inactive periods at night.
Adaptive (bi-level) wall packs that dynamically adjust their output to half during periods of vacancy can provide significant energy savings—with no compromise on safety. Conventional wall packs tend toward metal halide, HPS or compact fluorescent sources. To reduce energy waste and comply with the latest requirements, these luminaires can be retrofitted with occupancy-based systems. However, the report recommends the best long-term approach for creating outdoor lighting efficiency is to switch out the existing wall packs with entirely new luminaires that have on-board motion sensors or are integrated with an appropriately located, centralized sensor. Another Title 24, Part 6 requirement is that wall packs be equipped with photosensors and automatic scheduling controls to prevent energy waste during daylight hours.
Most parking lot lighting in California schools consists of pole-mounted high-intensity discharge (HID) luminaires, typically high-pressure sodium (HPS) and, to a lesser extent, metal halide (MH) and fluorescent sources. Here’s the new standard for parking lots: Retrofitting HPS lamps with LED, induction or ceramic metal halide sources that integrate adaptive, occupancy-based, bi-level controls results in energy savings ranging from 30 to 75 percent. Similar to wall packs, bi-level control technologies can enhance outdoor lighting efficiency by reducing parking lot lighting power at least 50 percent during vacant periods and automatically increase light levels when occupants approach the area.
The theme of reducing wasted light by halving output during inactivity continues with canopy lighting. Canopy lighting applications also provide significant savings with the addition of higher efficacy light sources operating with bi-level controls that reduce power when unnecessary. The report recommends a variety of new luminaire options that are highly cost-effective, energy-efficient and easy to retrofit onto the existing electrical junction box (“J box”). These include LED, induction and multi-lamp weatherproof fluorescent luminaires that have built-in occupancy sensors and bi-level controllers. Another retrofit option for existing canopies is centralized control through stand-alone occupancy sensors used to control multiple luminaires. Make sure that the luminaire and control components you select include high-quality, weather-proof sensors that provide sufficient coverage for occupancy detection. The same type of adaptive lighting recommended for use under PV canopies can be generalized across multiple applications, such as outdoor corridors and covered pathways.
Here’s a clear illustration of the impact of this kind of retrofit: Bi-level luminaires increase outdoor lighting efficiency and reduce lighting energy use 50 percent when operating at full power and yield 80 percent energy savings when the space is vacant and the lights dim. On top of that, this kind of retrofit offers the potential for improved visibility, reduced light trespass, and virtually maintenance-free upkeep for 20 to 25 years. All strategies listed follow k-12 Proposition 39 standards.