Measurement of interior green space and its impact on indoor environmental quality

Abstract

Indoor environmental quality directly affects the comfort, performance, and well-being of occupants. It is an important issue given people spend a large amount of time indoors. Plants absorb sunlight, capture carbon dioxide and transpire water. Thus, adding greenery such as potted plants and green walls to indoor environments has attracted interest as a way to positively influence these three aspects of indoor environmental quality and, by extension, the well-being of people using these spaces. However, experimental studies have focused on laboratory or controlled settings rather than the indoor environments that people use such as offices. This thesis aimed to develop a rapid and simple method to quantify interior greenery; measure the impact of interior plants on CO2 concentration, air temperature and relative humidity in office settings; and to evaluate the effects of indoor plants on hygrothermal comfort in naturally ventilated and air-conditioned office environments. In the first part of this thesis I developed an Interior Green View Index to rapidly measure interior greenery. This method is based on capturing and classifying 360 panoramic images taken with a conventional 360 red-green-blue camera. There was a high correlation between the iGVI and manual measurements of indoor greenery, though the accuracy of the iGVI declined in larger and highly illuminated interior spaces. These results suggested that the iGVI method is a useful tool for quickly estimating interior greenery. For the second part of this thesis I investigated the impact of indoor plants on three aspects of IEQ: relative humidity, indoor air temperature, and CO2 concentration in naturally ventilated offices. Using a Latin square design, three treatments control, low volume, and high volume of Nephrolepis exaltata: were rotated across three offices over six periods. Relative humidity increased significantly with the number of indoor plants, from a median of 29.1% to 38.9% and 49.2%. My results support using indoor plants to increase relative humidity, which enhances some aspects of well-being and productivity, particularly in drier climates. In the third part of this thesis, I tested the effect of interior greenery on hygrothermal comfort in offices with differing ventilation systems: naturally ventilated and air-conditioned. Using a Latin square design, varying volumes of Nephrolepis exaltata were introduced into three offices over six days. Indoor plants did not significantly alter hygrothermal comfort in air-conditioned nor naturally ventilated settings. Hygrothermal comfort in both air-conditioned and naturally ventilated offices was consistently rated as 'marginally comfortable', regardless of the volumes of plants introduced. This thesis contributes to the understanding of interior green spaces in office environments through three main aspects: developing a rapid method to quantify interior greenery, investigating the impact of indoor plants on environmental quality, and analyzing hygrothermal comfort in different ventilation settings. The key findings demonstrate that while indoor plants significantly increase relative humidity, they have minimal measurable effects on CO2 levels and air temperature in modern office environments. This limited impact is likely due to advanced ventilation systems and controlled climates in contemporary offices. However, the aesthetic and potential psychological benefits of indoor plants remain notable. The thesis suggests that interior green spaces, while not a standalone solution for all aspects of indoor environmental quality, can be an effective component in a holistic approach to improving office environments. Show more