Effects of Climatic Conditions, Season and Environmental Factors on CO₂ Concentrations in Naturally Ventilated Primary Schools in Chile

• Main Authors: Muriel Diaz, Mario Cools, Maureen Trebilcock, Beatriz Piderit-Moreno, Shady Attia
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Sustainability
• Subjects: educational building; free-running; carbon dioxide; indoor air temperature; interaction; occupant density
• Online Access: https://www.mdpi.com/2071-1050/13/8/4139

Between the ages of 6 and 18, children spend between 30 and 42 h a week at school, mostly indoors, where indoor environmental quality is usually deficient and does not favor learning. The difficulty of delivering indoor air quality (IAQ) in learning facilities is related to high occupancy rates and low interaction levels with windows. In non-industrialized countries, as in the cases presented, most classrooms have no mechanical ventilation, due to energy poverty and lack of normative requirements. This fact heavily impacts the indoor air quality and students’ learning outcomes. The aim of the paper is to identify the factors that determine acceptable CO₂ concentrations. Therefore, it studies air quality in free-running and naturally ventilated primary schools in Chile, aiming to identify the impact of contextual, occupant, and building design factors, using CO₂ concentration as a proxy for IAQ. The monitoring of CO₂, temperature, and humidity revealed that indoor air CO₂ concentration is above 1400 ppm most of the time, with peaks of 5000 ppm during the day, especially in winter. The statistical analysis indicates that CO₂ is dependent on climate, seasonality, and indoor temperature, while it is independent of outside temperature in heated classrooms. The odds of having acceptable concentrations of CO₂ are bigger when indoor temperatures are high, and there is a need to ventilate for cooling.