Ventilation retrofit design for existing primary and secondary school classrooms under epidemic conditions

Abstract

In the context of regular epidemic prevention and control, most primary and secondary schools in developing countries are naturally ventilated. They are unable to use measures such as air filters equipped with centralized mechanical ventilation systems and demand-controlled ventilation. Therefore, the feasibility of using automatic control of negative pressure ventilation (NPV) in conjunction with CO2 concentration detectors to reduce the rate of infection in the classroom was investigated. Firstly, the CO2 concentration threshold calculation for epidemic prevention was carried out, and then the measured data of the classroom was fitted with the Computational Fluid Dynamics (CFD) simulation data to establish a simulation and analysis platform to comprehensively evaluate different NPV conditions. The results show that NPV can control the direction of airflow and CO2 concentration in the teaching room, which can significantly reduce the risk of infection, and that Upward Supply Upward Return NPV with automatic control of the CO2 concentration detector and the combination of windshields can protect the students from cross-infection. The study aims to optimize classroom ventilation strategies for epidemic proofing through low-cost building modifications, which could inform the retrofitting of hundreds of thousands of established primary and secondary schools in developing countries. Practical Application Ventilation systems controlled by environmental parameters have the advantages of low cost, high automation, and ease of operation. This system makes designing classrooms to combat airborne epidemics easier by implementing simple retrofitting measures for developing countries where natural ventilation is predominantly used and where most classrooms are not equipped with fresh air ducts. Tests of the top inlet and top return ventilation system proposed in this paper found that the classroom’s measured indoor carbon dioxide concentrations were reduced to below the theoretical limits.