On-site measurements for noise reduction through open windows of classrooms with different building dispositions

In Korea, mitigation measures for traffic noise at schools are implemented during urban planning to meet the acceptable level (less than 65 dBA at a building façade) stipulated by the Environmental Impact Assessment (EIA). Meanwhile, traffic noise at schools is managed to satisfy the acceptable level (less than 55 dBA in a classroom with open windows) indicated by the School Health Act (SHA). This variation indicates the possibility to exceed the acceptable SHA level for EIA-approved schools if noise reduction through open windows is less than 10 dBA. Thus, this study carried out onsite measurements for noise reduction through classrooms' open windows at 19 schools to suggest the appropriate EIA level to meet the acceptable SHA level. The building dispositions were categorized into four types as; (1) Parallel disposition between road and classroom (P type), (2) Perpendicular disposition between road and classroom (V type), (3) Cross-sectional disposition between road and classroom (PV type), and (4) Parallel disposition between road and hallway (H type). The results showed different noise reduction through open windows according to the type of building dispositions in the order of H (16.9 dBA), V (9.2 dBA), PV (8.4 dBA), and P (6.7 dBA) types, attributed to the change in incidence angles between the road and open windows, confirmed by measurements using a speaker. In conclusion, the acceptable noise level on SHA could be exceeded especially for the P, PV, and V types, indicating the need for different noise mitigation measures according to building dispositions.