Energy-efficient buildings are crucial for reducing environmental impacts by reducing the power consumption by the inhabitants and ultimately reducing greenhouse gas emissions. It offers economic benefits through energy cost reduction. Worldwide, there is a focus on the design of new zero-energy buildings, which has zero energy consumption. It is due to changes in structural design, ventilated facades, façade design, artificial building envelop, improved thermal insulation materials, and application of phase change materials (PCM). In this experimental study, a building has been constructed in the composite climate of India by providing an artificial envelope on outer side of south facing wall, which is a combination of air-gap and PCM layer. The composite climate region experiences extreme summer and mild winter temperatures. It has been found that the peak room temperature during April month was lower than the room with insulation. The average test room remained low as compared to the reference room. Experimental data can be referred for the validation of building simulation code EnergyPlus to extend the study for any other region in India or abroad.