Thermal characterization of a modular living wall for improved energy performance in buildings

Vertical vegetation systems are an innovative passive method for decreasing the thermal energy demand of buildings while increasing the quality of urban life. The main objective of this work is to calculate the effectiveness of vegetation in reducing thermal loads analytically. For this purpose, the thermal energy performance of the modular living wall was compared with a traditional double facade construction system to evaluate the influence of vegetation using Stochastic Differential Equations models. The research was carried out experimentally using a real-scale PASLINK test cell. The thermal behaviour of a double leaf bare wall and the same double leaf wall converted into a modular living wall were calculated for different summertime and wintertime periods. In both studied cases, the temperature of the exterior surface of the bare wall is taken at the same place regardless of whether or not there is greenery system in the energy balance. With this simplification, the effect of the modular living wall can be identified within the estimated coefficients. The thermal resistance of the conventional double facade increased 0.74 (m2 K)/W over the non-greened wall, which represents a weighted increase of 49%. Additionally, the experimental results showed that the evapotraspiration processes that take place in the living wall lead to an increase in the combined convection-radiation coefficient, which reduces the overheating of the facade. Moreover, the effective solar absorptivity value of the outermost surface of the bare wall has been reduced an 85% thanks to the living wall, which confirms the high capacity of the living wall to reduce solar heat gains.

Automated summary

Vertical vegetation systems are an innovative method for reducing energy demand and improving urban life. This study compares the thermal performance of a modular living wall with a traditional double facade system using stochastic differential equations models. Experimental results show that the living wall reduces solar heat gains and overheating of the facade, while increasing the thermal resistance and combined convection-radiation coefficient.