Improving Indoor Air Quality in California Schools4

2019

With funding from the California Energy Commission, UC Davis and Berkeley Lab researchers visited 104 classrooms in 11 schools throughout California that had been retrofitted with new heating, ventilation and air conditioning (HVAC) units in the past three years. They evaluated the HVAC systems, carbon dioxide (CO₂) concentrations, and indoor temperature and humidity through field inspections, monitoring, and a teacher survey.

• Standards for ventilation rates balance indoor air quality and energy efficiency­­. ASHRAE, a global professional society that sets standards for building performance, specifies a minimum ventilation rate for classrooms of 15 cubic feet per minute per person. In California, the 2016 Building Energy Efficiency Standards, also known as Title 24, have the same ventilation requirement for classrooms. Using measured CO₂ concentrations and the number of people in the classroom, researchers found only about 15% of classrooms met the ventilation standard.
• Researchers characterized each HVAC system by documenting the number of problems due to its hardware, controls and filter maintenance. Classrooms with one or more HVAC problems tended to have lower ventilation rates and higher CO₂ levels.
• In addition to ventilation, thermal comfort impacts student performance. In this study, about 60% of the classrooms were warmer than the recommended average maximum temperature of 73°F. Also, 30% of the teachers surveyed were dissatisfied or very dissatisfied with the temperature in their classroom, and about 10% said the temperature interfered “a lot with the learning environment.”