Wake County (N.C.) Public School System
The “problem” that the Wake County Public School System (WCPSS) faced over the past 5 years — growing by 13.5% in size (adding 2.6 million square feet, bringing our total to 21.8 million gsf) and 11.6% in enrollment (adding 15,500 students, bringing our total to 149,508) is one that many communities would envy. The challenge was in dealing with this rapid growth during an economic downturn. While funding at the state and local levels was reduced, there was still an expectation that existing standards for excellence in education, maintenance, and sustainability would be maintained.
WCPSS was aided in facing this challenge by an existing infrastructure that sees sustainability as an opportunity. New buildings and renovations are built to meet energy design guidelines prepared by the school system and the county government. All buildings have building automation systems, and we employ a utility analyst to analyze performance. An Environmental Stewardship program engages students and staff through its EnergySavers program, which trains student teams to patrol their schools to identify wasted energy, and a FEED THE BIN recycling program operated in conjunction with Wake County Environmental Services. WCPSS was able to significantly reduce costs by stepping up its sustainability efforts.
There are 3 broad approaches toward reducing energy use: Replacing inefficient equipment, modifying occupant behavior, and controlling building operations. Reduced funding levels removed elective equipment replacement as an option. By necessity, our energy conservation focus came from leveraging the people and systems we had in place to improve building operations.
Our primary tool in this effort was the Building Automation System (BAS), which is used to schedule the buildings to provide comfortable temperatures when the buildings are occupied and allow temperatures to drift away from those thermostat setpoints when the buildings are unoccupied. When a higher than anticipated electricity rate increase was approved in December 2008, the global thermostat setpoints in the BAS were changed by one degree to reduce energy use and costs. In response to budget reductions the following year, the setpoints were changed by an additional degree, and the time frame that was considered “occupied” was changed to match the school’s bell schedule. (Prior to this, the occupied period had begun one hour before the school’s daily schedule.) Additionally, the amount of time allotted for a timed override (used when a school is used outside the regularly defined day without scheduling for after hours use with our BAS staff) was reduced from 3 hours to 1 hour.
Utility bills and other metering information were reviewed to observe when energy or water usage moved outside expected operating levels. By identifying and reacting to high usage as quickly as possible, we limited the excess energy use from common maintenance issues.
A challenge we experienced was a temporary decrease in comfort, measured by the number of “too hot/too cold” calls our maintenance department received when we imposed the second degree of thermostat setpoint changes and shortened the length of the occupied period. This was not an unexpected outcome; however, the need for quick results across 170 campuses drove the decision. As the economic situation improved, those additional restrictions were dropped beginning in 2012-2013, so the results we show below were not based on occupant discomfort.
As a result of our sustainability efforts, our total energy use increased by only 0.8% from 2007-2008 to 2012-2013, even as total square footage increased by 13.5%. Our energy use index decreased from 56 kBTU/sf to 49.7 kBTU/sf, resulting in 137.6 million kBTU of energy use that was avoided in 2012-2013. From an environmental standpoint, this prevented the emission of 17,600 metric tons of carbon dioxide, or the amount that would be sequestered by 22.5 square miles of forest. From a cost standpoint, this equated to $2.96 million in avoided cost from energy in 2012-2013. We avoided an additional $280,000 due to increased water efficiency plus $1.2 million more from utility bill analysis and fuel sourcing changes.
These sustainability efforts were tracked in EPA Energy Star’s Portfolio Manager. WCPSS earned recognition as an Energy Star Leader Top Performer for having a portfolio-wide score of 78, which means that the normalized energy performance of WCPSS is better than or equal to that of 78% of all K-12 schools nationwide. Recognition was also given for improving performance by 12% from our 2007-2008 baseline.
The improvements seen through this past year are a stepping-stone on our path to continued improvement in sustainability. We hope to use our current success to win support for expanding our sustainability efforts and results.
Joe Desormeaux, Assistant Superintendent for Facilities
Greg Clark, Senior Director for Maintenance and Facilities
Nate Slavik, Director of Energy and Physical Plant
Scott Thompson, Building Automation Systems manager
Lib Reid McGowan, Utility Analyst
Building Automation System crew:
Scott Masters, Jeff Rupert, Jason Gray, Freddie Ziglar, Phil Tarnaski, John Andrews
10% Improvement in Overall Energy Performance (PDF)
Top Overall Energy Performance (PDF)
Energy Usage Graph (xls)
