Improved Energy Efficiency and Indoor Air Quality for Relocatable Classrooms
On school campuses throughout the U.S., portable structures are multiplying as school districts try to keep up with increasing student enrollments and requirements for class-size reduction. In California alone schools already use 85,000 relocatable classrooms (RCs), and the number is increasing at the rate of 4,000 to 10,000 structures per year. In the U.S. as a whole, there are 600,000 RCs serving about 1.4 million students.
School districts also face the problem of operating and maintaining school facilities and paying increasing energy bills in the face of budget pressures.
As in other buildings, indoor air and environmental quality can be a problem in schools for reasons ranging from incorrect design and operation of building equipment to improper maintenance.
Energy-efficient structures can help school districts by lowering their energy bills, and structures designed with good air quality in mind help students and teachers stay healthy and sharp in the classroom. Evidence from scientific studies suggests that improving the indoor air quality of classrooms can lead to higher attendance rates and lower absenteeism caused by illness.
Could relocatable classrooms be built that are energy-efficient and provide good indoor air quality (IAQ) for their occupants? Researchers from Lawrence Berkeley National Laboratory's Environmental Energy Technologies Division teamed with stakeholders including a manufacturer of RCs, and school districts to find out.
Air Quality Found to Be a Problem in Classrooms
A 2001 California Air Resources Board study of the indoor air quality in California classrooms found that that the HVAC units in a significant number of classrooms were shut off because of excessive noise produced by the HVAC unit. This would lead to a build up of carbon dioxide in the classroom, and uncomfortable teaching and learning conditions. EETD researchers began to address the problem.
They joined with two school districts in California, the Bard Manufacturing Company, a maker of wall-mounted HVAC systems in RCs, Geary Pacific Supply Corporation, the west coast distributor of Bard HVAC equipment to develop a new HVAC system for RCs—improved heat pump air conditioning (IHPAC).
To test their technology, the team designed a classroom with two HVAC systems: a standard 10-SEER heat-pump air conditioner system (SEER stands for seasonal energy-efficiency rating), and the energy-efficient IHPAC.
Improved System Improved the Classroom
Berkeley Lab researchers first tested the prototype IHPAC in the specially designed classroom test facility. Then, 10 were installed at four schools throughout California for a year of monitoring, so they could be compared against conventional heat pump air conditioning systems.
Real-time monitoring showed that classroom ventilation in the IHPAC was considerably improved over the 10 SEER classrooms. IHPAC controls provided continuous ventilation during operation while ventilation in the 10 SEER classrooms was more variable—thermostats there turned on ventilation only when heating or cooling, and teachers would turn off these noisy conventional units during class. The testing found that the IHPAC system was very quiet, as low as 32.1 decibels (dbA).
The IHPAC's continuous ventilation lowered the concentration of carbon dioxide, aldehyde, and other volatile organic compounds in the classrooms significantly, and it operated at up to 44% more efficient during cooling, and up 38% more efficient during heating than standard wall-mount heat pumps. The research team's estimates suggest that IHPAC technology can reduce energy needed for HVAC by 50 to 70 percent, compared to the conventional technology.
Bard Manufacturing is now selling RCs with the improved HVAC systems into markets in California under the name Quiet Climate 2. They are planning to sell to markets throughout the United States.
- Improving Ventilation and Saving Energy in RCs website
- Bard's Quiet Climate
- "Better Air Quality and Energy Efficiency for Classrooms"
- "Improving Ventilation and Saving Energy: Final Report on Indoor Environmental Quality and Energy Monitoring in Sixteen Relocatable Classrooms"