Thermal performance of indirect green fa?ade in composite climate of India

Many experimental and theoretical studies have shown that green facades can increase the thermal efficiency of a building's facade. Previous field research has focused on humid subtropical and tropical climates and the Mediterranean climate. There has been no research directed at the Indian climates. Moreover, the studies have evaluated microclimate and inside surface or ambient temperatures; however, whether its application creates a comfortable environment is yet to be found. A real-time study was performed to assess the effect of indirect green facade systems on the glazed facade to evaluate thermal comfort in India's composite climate (Hot semi-arid climate Bsh). Two glazed facades were examined: one with a green screen of Bengal clock vine and the other bare to serve as the base case. The tem-peratures on the southwest-oriented green facades were up to 8.1 degrees C lower than the respective temperatures of the uncovered facade. In summer, the nighttime temperatures for the vegetated facade were up to 5.1 degrees C higher than those for the base facade. No significant insulating effect in the cold season was observed. The highest reduction was seen between 2 p.m. and 6 p.m., implying the relation with high solar radiation during these hours in the southwest orientation. While the green facade helped lower building temperatures, it also raised relative humidity, making an uncomfortable indoor thermal environment. The study also aimed to find the appropriate distance to install a green facade. Although a green facade controls temperature, the study finds that a proper distance between greenery and the facade surface improves the system's thermal performance. According to the study, installing a green facade with more than 150 mm distance between the greenery system and the facade surface is optimum in New Delhi's composite climate. The study's findings try to fill the gap of the impact of green facades in the Indian climate to see its applicability on a larger scale; however, the results show increased discomfort with higher relative humidity as the climate changes from dry to humid.