Sustainable Natural Ventilation Strategies for Acceptable Indoor Air Quality: An Experimental and Simulated Study in a Small Office During the Winter Season

This study proposes sustainable natural ventilation strategies using the periodic opening and closing of windows and doors to maintain acceptable indoor air quality in a small office space during the winter season. Field experiments were conducted in a 26.8 m² university office room in Seoul, Korea, measuring the indoor and outdoor temperature, humidity, wind speed, carbon dioxide concentration, and fine dust levels. A simulation model based on a first-order differential equation was developed using EES software (version 9) to predict indoor CO₂ concentrations at one-minute intervals. The simulation results showed good agreement with the experimental data, validating the accuracy of the modeling approach. Based on the validated model, practical ventilation durations and intervals were derived according to the occupant number and room volume, ensuring that indoor CO₂ concentrations remained below the recommended 1000 ppm threshold. The results demonstrate that simple, periodic natural ventilation is effective in maintaining acceptable indoor air quality. As a passive strategy requiring no electrical energy, it offers a sustainable and low-cost solution for creating a healthy indoor environment.