CH-24-C088 - Indoor Greenery Systems: How Do They Impact Occupant Thermal Comfort?

Indoor living walls serve multiple purposes in buildings such as air purification, thermal insulation, noise reduction, improved productivity, and occupant well-being. However, there is a lack of studies on the impact of indoor living walls on occupant thermal comfort and how this varies at different temperatures and sizes of living walls. Furthermore, as plants have a cooling effect on their surroundings via evapotranspiration, there is a need to investigate the influence of indoor living walls on occupant satisfaction with the indoor environment. Therefore, this study evaluates the impact of indoor living walls on occupants’ thermal comfort at different temperature setpoints. Measurements including average room temperature, relative humidity, globe temperature, and carbon dioxide levels were collected for the duration of the experiment. Subjective surveys that measured occupants’ thermal and moisture sensation, satisfaction, and preference were administered during the experiment. The survey also included questions that helped evaluate the satisfaction of occupants with the presence of the living wall. The study was performed at different room temperature set points - 23, 24, 24.5, 25, 26, 26.5, and 27 ℃ (73.4, 75.2, 76.1, 77, 78.8, 79.7, 80.6 °F) - for both the baseline scenario (without living walls) and the living wall scenario (25% leaf-to-floor area ratio). We had between 26 - 32 participants for each temperature setpoint. Based on the Kruskal-Wallis tests, the presence of the living wall was found to have an impact on occupants’ thermal sensation votes at all temperature setpoints. On average the thermal sensation votes (TSV) were lower by up to 0.7 points at a room temperature of 24.5 ℃ (76.1 °F) compared to the baseline. We found a strong correlation between TSV and room temperature as well as a slightly strong correlation between TSV and carbon dioxide levels. In terms of thermal preference, we found a 15% reduction in participants wanting it “cooler” with the living wall present. The difference between male and female TSV also shrunk by 0.2 TSV points with the living wall present. Overall, having a living wall present led to a wider comfortable temperature range compared to the baseline. The upper limit was higher with the living wall present by 0.74 ℃ (1.34 ℉) and 0.89 ℃ (1.61 ℉) at 10% and 20% PPD respectively, compared to the baseline. This suggests that with the living wall present, occupants can adapt to and endure higher temperatures which would have a positive impact on energy efficiency for current and future buildings.