Assessing the thermal performance of living wall systems in wet and cold climates during the winter

Abstract

As eastern China rapidly urbanizes, living walls are spreading swiftly across cities and consequently resulting in its stronger influence on the urban thermal environment. The objective of this study is to assess the effect of external living wall systems (LWSs) on indoor thermal environments in winters with low temperatures and high humidity levels. Four containers with different outer facades were arranged in Hangzhou and a comparative analysis was conducted on changes in the internal and external thermal environments of these containers. Results reveal that both the soil-filled planter pots and plants positioned on the LWSs play a role in indoor insulation while pots have a more stable effect. Good thermal performance of living walls can improve the energy efficiency of buildings. When the north-facing walls of the containers were equipped with planter pots, a bamboo living wall or a living wall with other plants, the internal temperatures were 0.4 °C, 1.7 °C and 1 °C higher during the insulation period, respectively, relative to those of the reference container, and the all-day insulation period of the north-facing LWSs lasted more than 20 h a day. By contrast, thermal benefit of the north-and south-facing LWSs was weaker. Compared to more widely used plant species, dwarf bamboo increased insulation and wind resistance levels on the living walls, creating significantly higher temperatures on living wall surfaces and within containers in winter, indicating that plant features have a strong positive impact on the insulating features of living walls. This study not only makes up for the lack of research on the thermal performance of LWSs in the researched area during the winter, but also is of great significance to the development and application of living walls with better thermal benefits, such as orientation setting, plant selection, building energy saving, etc.