The purpose of this research is to investigate how indoor air quality might be improved by installing particular ornamental plants available in Thailand. Traditionally, ventilation fans have been used to encourage fresh air into living areas in order to reduce CO2 levels. This consumes more energy than using ornamental plants. Our research screens three types of ornamental plants and selects one to investigate its potential for enhancing indoor air quality by reducing carbon dioxide levels. The three plants are epipremnum aureum, spathiphyllum wallisei, and dieffenbachia sp. The propensity to reduce carbon dioxide levels of each plant was preliminary screened using a closed flux chamber method over a 24-hour period. It was found that epipremnum aureum had the ability to absorb carbon dioxide better than the others. The epipremnum aureum was then put in a classroom to investigate variables in two further experiments. The ability to improve air quality in terms of sensitivity to various light concentrations and the number of plants in the room are explored. It was found that epipremnum aureum should be placed within a distance of 1.5 meters from windows to achieve the appropriate light concentration to enhance indoor air quality. It was also found that 150 pots of epipremnum aureum had the propensity to reduce CO2 by 430 ppm in a classroom of 20 students for an 80-minute class. The use of sufficient amounts of epipremnum aureum can improve air quality in classrooms. A model to estimate numbers of such plants needed in classrooms is also presented.