Ventilation rates in naturally ventilated primary schools in the UK; Contextual, Occupant and Building-related (COB) factors

Abstract

Indoor Air Quality (IAQ) in classrooms is assessed by CO2 levels and Ventilation Rates (VRs). Factors affecting VRs fall into Contextual, Occupant and Building (COB) related factors. This study investigates how VRs are affected by COB factors in 29 naturally-ventilated classrooms in the UK during Non-Heating and Heating seasons. Building-related factors classify classrooms with high or low potentials for natural ventilation, with 45% of classrooms having high potentials. Contextual factors including season, operative temperature (Top), outdoor temperature (Tout), 'Top-Tout' and air density can limit or increase VRs. Occupant-related factors classify occupant's good or poor practice of environmental adaptive behaviours. 'Open area' as a reflection of all COB factors is strongly correlated with ventilation rates. Results show that 12% and 19% of variations in ventilation rates are explained by open areas during non-heating and heating seasons, respectively. Findings highlight that to have VR of 8±1.28 l/s.p during non-heating seasons and VR of 8±1.07 l/s.p during heating seasons, average open areas of 3.8m 2 and 2m 2 are required, respectively. This difference can mostly be explained by temperature difference between inside and outside. Results show COB factors need to be considered holistically to maintain adequate VRs. Classrooms in which all COB factors are met provide average VR of 11 l/s.p and classrooms in which none of COB factors are met provide average VR is 3.1 l/s.p. This study highlights that 40% of classrooms according to EN 13779 and 80% of classrooms according to ASHRAE Standard fail to provide adequate VRs.

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

“…A binary model using Binary Logistic Regression (BLR) was applied to explore the relationship between acceptable CO 2 concentrations (response variable) and contextual, occupant, and building [37] factors (predictor variables), as shown in Table 4. The threshold values expressed in the table were taken from EN 13779:2007 for CO 2 concentrations, temperature, and humidity thresholds and were defined, based on the proposed new regulation for IEQ in schools in Chile (not published).…”

“…In this study, the dependent variable will be CO2 concentration as a proxy for IAQ. In contrast, the independent variables were defined, based on the characterization made by Korsavi [37] and the literature review. The factors under study are contextual factors: season, operative temperature [44][45][46], outside temperature, and humidity; building-related factors: room′s volume and dimensions; and occupant-related factors: occupant density [36].…”

“…Korsavi et al [36] suggest that some factors related to IAQ are occupants' adaptive behavior, occupancy patterns, CO 2 generation rates, and occupant density and highlight the potential of the classrooms to facilitate adaptative behaviors. Based on studying a sample of 29 naturally-ventilated classrooms in the UK during non-heating and heating seasons, they proposed a classification of the main factors affecting ventilation rates, and, therefore, IAQ sorting them into three groups: contextual, occupant-related, and building-related (COB) factors [37].…”

Research on the effect of different position on classroom ventilation in a “L” type teaching building

“… Luca Stabile [ 27 ] 2020 Cassino, Italy (Mild) Mechanical Measurement Application of mechanical ventilation system with energy recovery unit significantly save 32% energy consumption via post ventilation retrofit for school. Sepideh Sadat Korsavi et al [ 32 ] 2020 UK(Mild) Natural Measurement Opening strategy should also take the season condition into consideration in order to improve indoor air quality. Beungyong Park and Sihwan Lee [ 33 ] 2020 Tokyo Japan(Mild) Natural CFD&Measurement An improved ventilation strategy could effectively build needed interior situation and decrease the energy consumption of approximately 30%.…”

“…Furthermore, for classrooms with carpets, it is indispensable to utilize special air strategy to disperse the additional dust caused by carpets [ 23 ]. Sepideh Sadat Korsavi et al pointed out that opening strategy should also take the season condition into consideration in order to improve indoor air quality [ 32 ].…”