North Carolina Performance Enhancement Relocatable Classrooms
Chapel Hill, North Carolina

NC PERC Unit

The NC Performance Enhanced Relocatable Classroom is located at Chapel Hill High School. There are 20 schools in the district and a total population of over 10,600 students. The school district currently has 42 relocatable classrooms and 8 were added for the school year 2003-2004. The North Carolina Solar Center has partnered with FSEC to help monitor the performance of the NC PERC experiment. The typical classroom used in this school district is a wood framed structure with gypsum ceiling; unlike the FL and NY typical classrooms, which used t-grid ceilings (for more detail see FL PERC and NY PERC). Over a full year of data collection,  the modified classroom achieved an overall energy savings of 46%. Total electricity use averaged 64.9 kWh/day in the control portable against 32.3 kWh in the improved one. The magnitude of the daily energy end uses is shown in the pie graph below, illustrating that space heating has made up the lion's share of energy use from November through March.

Measured average electricity end-uses in control portable
from November 1, 2003 through March 8, 2004

The timing of the savings are shown in the average daily load profiles shown in the plot below. FSEC is continuing to monitor this project and evaluate the modifications that were made as well as the performance over the entire year.

	Daylighting from overhead skylights inside the experimental classroom

FSEC monitored energy performance in both classrooms. All data was downloaded daily to FSEC via modem. Data summaries can be accessed online at the InfoMonitors web site. Detailed data queries and graphs can also be generated through FSEC's WebGet database.

*Leakage Testing performed – October 22, 2003

Skylight Design

Daylighting performance in the PERC unit was simulated to determine the size, layout and quantity of skylights that would optimize light levels in the classrooms. A program developed by HMG, SkyCalc was utilized using various supplemental electrical lighting scenarios. The simulated energy savings of using 4, 6 and 8 skylights in NC climate with continuously dimming electrical lighting operation are shown below (click to enlarge):

4 skylights		6 skylights		8 skylights

Below is the construction document for the NC PERC and detail that illustrates the skylight well strategy (click to enlarge).

To see construction status, future data collection, and specifications for other PERCs, please visit the links below.

NY PERC		FL PERC

Contacts

FSEC would like to especially thank the industry partners who have donated time and equipment in this worthwhile project. 

News Releases, Publications and Presentations

Class is a study in Energy Use – News Observer January 26, 2004 (Word 143KB)
New Mobile Classroom Earns High Marks for Energy Savings - NCSC News Release January 14, 2004 (Word 21KB)
Improving Performance in portable Classrooms - 2002 SEP/RA National Conference July 30, 2002 (PPT 15,456KB )
Research & Case Studies of Energy Efficiency in Schools – AIA SC Think Green Workshop April 4, 2003 (PPT 12,475KB )

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Note of Interest: Ceiling Insulation
Gypsum Wall Board ceilings are typical for this relocatable classrooms in this school district. Therefore, loose fill insulation is blown on top of the ceiling. The trusses are framed and the gypsum sheet rock is glued and fastened to the underside of the roof joists Then the insulation is sprayed, the roof/ceiling is then lifted into place. The skylight wells were framed prior to the insulation process, Gypsum ceilings are generally more air tight than t-grid ceilings.

Ventilation Method for NC PERC
Wall mounted CO2 Controller model # 8002 w/ display controls, modifies the ventilation fan speed to operate under these conditions (during occupancy):

• high speed when CO2 levels in the classroom at 1200 ppm or more
• off when CO2 levels in the classroom are at 550 ppm or less
• medium speed when CO2 levels are between 700ppm –1200ppm

Bard CS2000 Energy Management controller detects occupancy and allows the heating/cooling/ventilation systems to operate when the classroom is occupied, and also has pre-cool/pre-heat scheduling