Temporal Variations in Estimated Ventilation and Relative Performance based on Continuous CO_2 Monitoring in Offices

摘要

Indoor temperature, relative humidity, particulate matter, volatile organic compounds, and carbon dioxide (CO_2) concentrations were monitored continuously in the breathing zone of some 150 Finnish office buildings (average five rooms per building). For this study focusing on ventilation, we selected those 35 buildings that had data from at least six months in both 2016 and 2017. Daily outdoor air ventilation rates in each room were estimated based on the steady state / peak CO_2 approach for each day when the difference between maximum and minimum CO, concentration was > 100 ppm. In addition, we modelled relative work performance based on the daily ventilation rates. On the building level, estimated mean ventilation rates (SD) ranged from 18.4 (20.3) to 65.8 (21.6) l/ sperson. Temporal variations were seen by year, month and weekday, which could be partially explained by occupancy patterns and outdoor temperatures. Estimated work performance was high as compared to 6.5 l/ s'person, which exceeds the minimum required ventilation rate in Finland. Thus, improving performance by increasing ventilation rates would be limited in this sample. Building owners/ operators can access the monitoring results, including CO, concentrations, almost real-time using a web-based platform, which provides them an opportunity to use these data to improve environments cost-effectively. Platforms processing raw data into estimates and, moreover, suggestions or action plans, could be beneficial.