Thermal effects of vertical greening with creepers in different life stages on the outdoor environment under a cold climate

In this study, we assessed the direct and indirect thermal benefits of growing creepers on a building during four life stages (green, yellowish, yellowing, and wilting) based on field measurements of the temperature and humidity, and theoretical analysis. The results showed that the direct thermal benefits of creepers were significant in the green, yellowish, and yellowing stages, where they gradually decreased as the life stages progressed, with cooling gains of up to 8 °C in the green stage compared with the concrete wall, and the insulation benefits were still approximately 1 °C in the wilting stage. Creepers also had significant indirect thermal benefits in the green, yellowish, and yellowing stages, where the best cooling effect was obtained in the yellowish stage, but no significant indirect thermal benefits were found in the wilting stage. In addition, creepers could reduce the ambient air temperature by increasing the relative humidity in the surrounding environment. The results obtained in this study may provide a scientific reference to facilitate the construction of vertical greening in cold regions and to determine the specifications for related applications, as well as providing insights into vertical greening research at the same latitude.