Numerical Investigation of Indoor Environmental Conditions in an Office

Abstract

The purpose of this work is to present a study of the indoor environmental conditions of an office which is fully occupied and naturally ventilated by window and door opening. In order to investigate the mechanisms controlling the indoor environmental conditions, as well as the processes acting indoors, the CFD model PHOENICS and the numerical mass balance Multi-chamber Indoor Air Quality model (MIAQ) were applied. Model inputs were based on input data obtained from extensive experimental measurements that took place in the office. The indoor airflow, temperature and inert gaseous pollutant fields, as well as indoor air quality with respect to particulate pollution, were investigated under different occupancy conditions. Comparison of computed versus experimental results revealed that both numerical models performed in a satisfactory manner. Results revealed that the flow field is characterized by very low velocities with areas of uniform flow and isolated vortices depending on the presence of objects. The presence of people did not affect the patterns established. Pollutant and heat dispersal was found to be dominated by the general flow field, leading to areas of higher temperature and pollution. The MIAQ model indicated that deposition is an important mechanism in such micro-environments, which considerably affects indoor pollutant concentrations. Under the ventilation conditions examined, indoor air quality in relation to carbon dioxide concentration was found to be satisfactory. Exposure to particulates during the period of occupancy was below the 24 hour exposure limit derived from current European Standards.