Assessment of natural ventilation strategy to decrease the risk of COVID 19 infection at a rural elementary school

Javier M Rey-Hernández; Yolanda Arroyo-Gómez; Julio F San José-Alonso; Francisco J Rey-Martínez

doi:10.1016/j.heliyon.2023.e18271

Assessment of natural ventilation strategy to decrease the risk of COVID 19 infection at a rural elementary school

Heliyon. 2023 Jul 14;9(7):e18271. doi: 10.1016/j.heliyon.2023.e18271. eCollection 2023 Jul.

Authors

Javier M Rey-Hernández^{1

2

3

4}, Yolanda Arroyo-Gómez^{5

2

4}, Julio F San José-Alonso^{5

2

4}, Francisco J Rey-Martínez^{5

2

4}

Affiliations

¹ Department of Mechanical Engineering, Fluid Mechanics and Thermal Engines, Engineering School, University of Málaga (UMa), 29014 Málaga, Spain.
² Thermotechnology Consolidated Research Unit (UIC 053), University of Valladolid, Spain.
³ Energetics Research Group (TEP139), University of Málaga, Spain.
⁴ Institute of Advanced Production Technologies (ITAP), Spain.
⁵ Department of Energy and Fluid Mechanics, School of Engineering (EII), University of Valladolid (UVa), 47002 Valladolid, Spain.

Abstract

Natural ventilation in low-budget elementary schools is the main focus to ensure the health and comfort of its occupants, specifically when looking at the global pandemic related to SARS-COV-2. This paper presents an experimental and novel study of natural ventilation in a public elementary school (Los Zumacales), with a particularly low economic budget. The study was carried out during the winter months of the Covid 19 pandemic. The school is located in the rural area of Castilla y León (North-Western Spain) far from high traffic roads. In this study, a methodology of measuring CO₂ concentration was applied in nine classrooms in a school. The experimental study shows the level of natural ventilation in each classroom, expressed in Air Changes per Hour (ACH), using the Decay CO₂ concentration method. The method is proven by comparing the experimental values of the obtained ACH with those determined by the most powerful methods to achieve appropriate ventilation levels. Thus, ensuring health protection protocol in rural schools, against the COVID 19 pandemic. Harvard guide and Spanish regulations (RITE), two widely recognized methods have been used together with the experimentally obtained standard by Rey et al. Only one classroom showed a value lower than 3 indicating poor ventilation. In this study, the degree of thermal comfort in the nine classrooms were also analyzed according to the EN15251 standard. An average indoor temperature of approximately 19 °C was obtained, and the relative humidity was stable and correct according to Spanish regulations. In addition, the risk of infection in each classroom was estimated following the international method recommended by the federation of European Heating, Ventilation, and Air Conditioning Associations (REHVA). The probability of infection in all the cases studied was less than 14%. Therefore, this study provides a strong response against infections illnesses, such as Covid 19, in educational buildings where economic budgets of their facilities are low in both, maintenance and investment.

Keywords: ACH; Covid19; Decay CO2 concentration method; Low-cost ventilation strategy; Natural ventilation; Thermal comfort.