India is the second most developing country in the world. Also, as a significant energy consumer, India uses 25–40% of primary energy in buildings, which affects climate change, degrades the environment rapidly, and causes air pollution. Hence, it’s crucial to reduce the energy consumption in buildings. This paper is based on findings of experimental results. Three full-scale test beds named ‘Central Building Research Institute Test Bed’ (CBRITB) were constructed at Roorkee, Uttarakhand, to understand the peak load on air-conditioning for maintaining a constant, comfortable indoor environment. A parametric analysis is also performed using energy simulation software for the walling and roofing combinations for different climates in India, including Roorkee (composite climate). The heating and cooling load and total site energy are computed in kWh/Year. Twelve combinations of customized and conventional materials suitable for the particular walling and roofing assembly are chosen based on the availability, embedded embodied energy, and best performer from the previous research work carried out at CBRI. The study carried out above infers that Option 9 with Wall assembly of 225 mm thick AAC block and 70 mm EPS on the external surface in combination with Roof assembly of 140 mm roof slab (Concrete), 5 mm Polyurethane board, 120 mm EPS (Heavyweight), 4 mm Cement Plaster, and 12 mm Ceramic glazed tiles on the external surface, gives the minimum energy of 2953.55 kWh/Year. Similarly, the experimental results of the CBRITB match closely with the energy-simulated results with a variation of about 9–10%.