Community Commitment to a Green School
- By Daniel Cecil, Anthony Roy
- October 1st, 2011
When Westbrook, Maine, committed to building a new middle school to replace the overcrowded 40-year-old Wescott Junior High School, it was no surprise that many in the community wanted to be involved, but no one imagined that more than 400 people — city residents, teachers, students, councilors and school committee members — would actively participate on 17 sub-committees making recommendations on numerous components of the school’s design, operation, location and use of technology.
There was a strong commitment in Westbrook that the school be as efficient and as green as possible. The school was designed to be a high-performance school in conjunction with the Maine High-Performance School Program administered through Efficiency Maine, which sets energy saving goals and is managed by the Maine Public Utilities Commission.
Here is a summary of the school’s high-performance and energy-efficient features.
- HPU #1 - Classroom light fixtures have daylight harvesting dimming controls.
- HPU #2 - Variable speed drives on fans are only required for fans in excess of 10 hp. Drives are used on air handler fans regardless of horsepower and result in energy savings.
- HPU #3 - Enthalpy-wheel heat recovery in the classroom air handlers where ASHRAE 90.1 does not require it, but where high ventilation requirements support it.
- HPU #4 - Displacement ventilation controlled by occupancy sensors is provided even though ASHRAE 90.1 does not require it for these particular occupant densities.
- HPU #5 - CO2 monitoring to vary the quantity of outdoor air to match space demand.
- HPU #6 - Heating system uses radiant floors in the classroom and office areas.
- Running small water pumps instead of large air handlers to keep the building at temperature at night.
- HPU #7 - All fluorescent lamps are high-efficiency T8 and T5, and all ballasts are electronic with less than 10 perent total harmonic distortion.
When the Westbrook Middle School was designed, the building’s calculated energy consumption per the Trane Trace 700 program was 2,886,888 kWh per year for the ASHRAE-90.1 base building. After 18 months of operation, the electrical bills (this is a totally electrical building) show that the annual energy consumption of the building is 2,071,000 kWh per year for a total savings over ASHRAE of 28.3 percent.
- Exterior wall system with two-inch rigid insulation on the exterior face of the metal wall studs and sheathing to provide the highest R-value.
- Roof R value exceeds ASHRAE 90.1 requirements by 100 percent.
- Classroom wings are oriented on an east-west axis to take advantage of natural light.
- Large windows with low-E glass bring in lots of natural light.
- White TPO roof membrane reflects heat away from the building.
- Lighting system is controlled by a low-voltage control system that allows lights to be turned on/off from a central location.
- Rooms have motion sensors that turn off lights automatically after a preset period of time when the room is not in use.
- Mechanical design exceeds the Maine benchmark requirements that itself exceeds ASHRAE 90.1 energy goals by 20 percent.
- Air handlers are enclosed in heated mechanical rooms that lengthen their operational life over rooftop units and are easier to maintain.
- Premium efficiency electric motors and lights were specified.
- Systems controls are optimized through a building automation system.
- Installed groundwater source heat pump system.
Although the building committee decided not to go through the lengthy and expensive LEED certification process, architects did use LEED guidelines. Westbrook Middle School potentially would have met requirements to qualify for certification.