Evaluation of the suppressive effects on solar radiation for a building façade covered with green layers in the Kathmandu valley

Abstract

Various development projects in unplanned settlements in the Kathmandu valley have transformed natural spaces into artificial surfaces. For developing cities, such as Kathmandu, restoring vegetation in settled land would be very expensive. In such cases, vertical greening systems can have an efficient role in reintroducing nature to cities. Globally, this method is gaining popularity as a means of improving existing urban settings. However, this practice has not yet been adopted in Nepal because of limited research and awareness on vertical greening systems. Therefore, this study aimed to examine whether direct greening on outer walls can contribute to the effect of solar radiation in the Kathmandu valley, where the altitude is high. Field measurements were performed between vegetated and bare walls to evaluate temperature differences in and around the building. The results showed the remarkable effect on the heat capacity of a bare brick wall during summer in Nepal. Moreover, an evaluation of the effect of solar absorbance obtained by considering the sol-air temperature revealed that the heat storage of the wall could be reduced through direct greening on the outer wall.