Tillandsia usneoides (Spanish moss) is a natural "air plant" characterised with rootless and soilless. It can be intertwined into plant curtain of arbitrary shape installed in the air cavity of double skin facade (DSF) as intermediate shade. The research project aims in researching Tillandsia usneoides (TU) plant curtain and defining the shading effect and thermal performance of the double skin facade with Tillandsia usneoides plant curtain in hot summer in Shanghai, China. The instantaneous solar heat gain and the instantaneous solar heat gain coefficient (ISHGC) of double skin facade with different Tillandsia usneoides density were obtained. The experimental data prove that the ISHGC decreases with the increase of plant density and solar radiation of outside environment. The minimum value of instantaneous solar heat gain coefficient is 0.24 for double skin facade with plant density of 750 g/m(2). Further analysis on temperature distribution of each layer of double skin facade indicates that plant curtain can contribute to creation of comfortable indoor climate and energy saving because it decreases the temperature of interior facade. The change of plant density will not influence the temperature stratification of double skin facade. However, the increase of plant density exacerbated the overheating of outside air cavity of DSF. More effective measures such like watering the TU plant curtain should be considered to solve this problem. (C) 2011 Elsevier B.V. All rights reserved.