Improving Relocatable Classroom HVAC For Improved IEQ And Energy Efficiency

Relocatable classrooms (RCs) in California (CA) alone house about 2 million students in more than 80,000 structures. These buildings are typically under-ventilated, often due to low HVAC utilization because of excessive HVAC acoustic noise, and because when automatically operated they only ventilate during thermal conditioning. It can be predicted that such conditions affect the quality education and student health. These systems are also energy inefficient and peak-load demanding. With a manufacturer of wall-mounted HVAC systems, we are developing a new system addressing these problems. Design goals include a ≥30% increase the seasonal energy efficiency ratio (SEER) over the current SEER 10 system, noise reduction ≤45 dB(A), continuous ventilation meeting CA State code requirements (e.g. ASHRAE 62.1 ventilation standard of 7 l s^-1 per occupant and a pre-occupancy air purge). The prototype was operated in an RC test-bed to characterize its performance from the standpoint of ventilation, and thermal control, acoustical noise, and energy consumption. Ten of the new HVAC systems are also being monitored for one year in matched pairs with the current standard HVAC systems after being installed in identical occupied RCs in four schools in Northern and Southern CA. Continuous measurements include indoor and outdoor carbon dioxide, temperature, relative humidity, and HVAC power consumption. Additionally, acoustical noise levels; thermal comfort; and concentrations of volatile organic compounds, formaldehyde and acetaldehyde, and ozone will be measured on a regular schedule throughout the study year. Daily classroom occupancy rates will be collected from the class records. The potential IEQ and energy savings benefits of the system will be presented from preliminary data collected in the field.