Impact of living plants on the indoor air quality in a large modern building

Abstract

The purpose of this paper is to investigate the use of living plants in enhancing the indoor air quality (IAQ) and the general indoor environment within a large modern open-plan office building with a central atrium design and a building management system (BMS) in place. Poor indoor air quality was measured within the building, primarily due to the low relative humidity during the winter months. Previous literature suggests that the incorporation of plants in buildings helps to regulate relative humidity whilst also bringing perceptual benefits and potentially reducing short-term sickness absence.
The investigation was developed through quantitative and qualitative data. The quantitative element involved the use of experimental and control zones within the building, selected on the basis of orientation, user density and users' work roles. Plants were selected based on the transpiration rates of various commercially-available species. Relative humidity was continuously monitored using data loggers with half-hourly logging intervals for a duration of six months. Carbon dioxide gas concentration was measured using a dedicated hand-held sensor. Qualitative user perception data was gathered through the use of a structured questionnaire distributed to staff members working in each of the experimental and control zones.
Initial findings suggest that the plants have not instigated the positive effects on IAQ that were expected. The recorded data on relative humidity displayed only non-significant variations between the experimental and control zones. These findings are attributed, in part, to the atrium design, which results in a substantial volume of air within the building, leading to cross-contamination and excessive dilution of the introduced humidity as a result of plant transpiration. The study extends the previous, mainly laboratory-based, investigations to a real working environment. However, this introduces a range of other experimental factors, thus impacting the results.
Implications for further research and practice include the extension of this research approach to consider a wider selection of buildings studied over a longer period of time, taking further account of seasonal fluctuations and the impact of additional variables present in real working environments. The practical value of this study is evident through the sustainability aspect provided by the potential of indoor plants to reduce carbon emissions of the general built environment through the elimination or reduction in use of energy and capital-intensive humidification air-conditioning systems.