Study on the Thermal Performance of Cavity Moss Living Wall:Taking Wuhan as an Example

LIU Xiaohu; ZHONG Gangting; PAN Yichen; CHEN Qiuyu

doi:10.3969/j.issn.1000-0232.2024.11.010

Abstract：This paper investigates the thermal performance of the"cavity moss living wall,"which is a new technology model integrating a living plant wall and a double-glazed curtain wall.It obtains the heat transfer and thermal parameters to provide basic data support for evaluating,analyzing and optimizing the cavity moss living wall's thermal performance.The study also provides new ideas for applying and developing the living plant wall on double-glazed glass.First,the construction mode of the cavity moss living wall is designed.The moss has a small self-weight,does not need soil,and can use the cavity between the double-glazed glass as the growth space,with cis-type and T-shaped hanging methods and light and thin construction.It also regulates the thermal environment of the cavity and plays the role of shading,heat insulation,transpiration and heat preservation for the building.Second,double-glazed windows and moss modules are installed in two experimental rooms for physical experiments,and the effects of the moss living walls on the glass cavities and room temperatures are determined on hot and cold days,respectively.Then,the heat transfer process of the moss living wall module is analyzed in combination with the principle of heat balance,and the heat transfer coefficient and thermal resistance are calculated by the thermofluid meter method. The results show that the cavity moss living wall can reduce the overheating of the room and the glass cavity on hot days and the fluctuation of the room temperature on cold days.The T-shaped module can reduce the maximum room temperature by 1.0℃on hot days,the average temperature of the cavity by 1.9℃,and the maximum temperature difference of the room by 1.4℃on cold days.The cis-type moss module can reduce the maximum room temperature by 8.4℃on hot days,the average temperature of the cavity by 1.5℃,and the maximum temperature difference of the room by 1.5℃on cold days.The thermal effects of the cavity moss living wall include shading,heat dissipation,radiation and long-wave radiation convection.For the same amount of solar heat on the outside surface of the module,the amount of solar radiation transmitted through the double-glazed glass is the highest,followed by the T-shaped module,and the least by the cis-type module.On hot days,the total heat transfer to the interior is lower for cis-type and T-shaped modules compared to double-glazed glass in the daytime,only 55%and 79%of that for double-glazed glass,and similar to that for double-glazed glass modules at night.On cold days,both moss modules can reduce the amount of heat transfer to the interior during the daytime,but the heat transfer to the interior is higher than that of double-glazed glass at night,with the cis-type module being higher.The two suspension angles of the moss in the cavity make the overall thermal resistance of the module different:0.29 m2·K/W for the T-shaped moss module and 0.49 m2·K/W for the cis-type moss module,which are 1.12 and 1.89 times higher than that of the ordinary double-glazed glass,respectively. The higher the thermal resistance value,the better the thermal insulation performance of the enclosure.Hanging moss panels in the double-glazed glass is beneficial for enhancing the thermal insulation performance of double-glazed glass.On hot days,the thermal insulation effect of the cis-type cavity moss living wall is better.On cold days,the thermal insulation effect of the T-shaped module is better during the day,and the cis-type module is better at night.Adjusting the angle of rotation of the moss panels according to the climate and the time of day can improve the thermal comfort of the room and optimize the thermal insulation effect of the moss living wall. Instead of theoretical derivation and calculation of moss's transpiration and heat dissipation,heat balance analysis and heat transfer calculation are performed on the inner glass.Although it is not possible to derive the specific quantitative value of the transpiration and heat dissipation of moss,the difference in heat transfer performance between the moss module and the double-glazed module can be verified.The limitations of the experimental conditions led to the small scale of the double-glazed windows used in the practical test,and their thermal environments are somewhat different from those of real double-glazed curtain walls.