Case studies: Lighting controls for educational facitilies

ASHRAE Standard 90.1 requires lighting professionals to include power allowances, daylighting controls, functional testing, and submittals in their lighting designs. This discussion includes an overview of lighting control options along with best practices for lighting designers and electrical engineers in working with their clients.

02/16/2015


Riverside High School, Carson, Iowa

Challenge: Recoup a portion of construction cost through utility incentive rebates. Design should accommodate the changing occupancy loads through the day.

Solutions:

  • The lighting power density was 0.98 W/sq ft, compared to the code maximum of 1.2, which is a 20% improvement.
  • The lighting controls were designed around ASHRAE 90.1-2007.
  • The building was designed with vertical windows high up in walls of the breakout spaces, corridors, and commons areas to deliver daylighting into the central parts of the building to minimize artificial lighting.
  • Classrooms include both occupancy sensor controls and bi-level switching in all fixtures, with separate control for front of classroom versus general classroom lighting, and a manual-on, automatic-off lighting control scheme.
  • Central corridors and general occupancy rooms and areas are controlled via a series of networked programmable relay panels in various electrical rooms located throughout the facility. Programming for these spaces includes a programmed time off function with override to on at entry points to the building. Daylight dimming controls with occupancy sensor override were used for the cafeteria area, which also serves as a commons area.
  • Lighting controls in the gym, fitness, music, and other larger occupancy rooms are based on bi-level manual lighting reduction and overall occupancy sensor override control.
  • The design team worked with an outside energy consulting firm as part of a local electrical utility incentives program to estimate the payback based on various energy measures and incentives.
  • Exterior site lighting consists of LED pole fixtures in the parking lot with integral dual drivers capable of reducing 50% lighting output for each fixture. Mounted fixtures are designed to turn on at dusk and off at dawn.

Figure 1: The variety of lighting and daylighting options at Alfonza W. Davis Middle School, Omaha, Neb., work together to create the most cost-effective use of lights for a high-performance outcome. Alfonza W. Davis Middle School, Omaha, Neb.

Challenge: Ensure maximum natural daylighting into a three-level, 185,000-sq-ft, grade 6-8 middle school on an extremely sloped site.

Solutions:

  • The lighting power density was 0.92 W/sq ft, compared to the code maximum of 1.2, which is a 24% improvement.
  • The lighting controls meet IECC 2009.
  • Classrooms include both occupancy sensor controls and bi-level switching in all fixtures, with separate control for front of classroom versus general classroom lighting, and manual-on, automatic-off lighting control scheme.
  • Corridors are controlled by relays with automatic-off via time of day.
  • Occupancy sensors, in an automatic-on and automatic-off configuration, are used in offices, work rooms, storage rooms, restrooms, etc.
  • Automatic daylight harvesting and bi-level switching controls were installed in the large cafeteria space and media center.
  • Gymnasium: Relay control for automatic-off, low-voltage switches with the room broken up into multiple zones to allow for some lights to remain off if the entire gym is not in use. Bi-level switching allows for multiple uniform light levels that can be selected according to task.

Eric Kamin is a principal leader in DLR Group’s electrical engineering practice. He is skilled in developing specifications for primary and secondary power distribution, standby power systems, voice and data cabling systems, security systems, interior and exterior lighting design, and sports lighting design.



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