A biological experiment was conducted to optimize the energy and protein requirement for commercial broilers in environmentally controlled housing system. The experiment was conducted by feeding diets with different levels of energy (2850, 2950 and 3050 kcal/kg in pre-starter diet, 2950, 3050 and 3150 kcal/kg in starter diet and 3050, 3150 and 3250 kcal/kg in finisher diet) and protein (21.5, 22.5 and 23.5% in pre-starter diet, 20.5, 21.5 and 22.5% in starter diet and 19, 20 and 21% in finisher diet) to commercial broilers for a period of five weeks to assess the production performance. The biological experiment was carried out with five hundred and seventy six (each 288 in environmentally controlled deep litter house and open sided deep litter house), sex separated, day-old, commercial (Vencobb 400) broiler chicks belonging to single hatch. The chicks were wing banded, weighed and randomly allotted into nine treatment groups with four replicates of eight chicks each and housed in both environmentally controlled and open sided housing systems. All chicks were reared up to 5 weeks under standard managemental conditions. During this experimental period, data on body weight and feed consumption were recorded at weekly interval and mortality was recorded at occurrence. The results of the experiment revealed that the energy and protein content of the diet had significantly influenced the body weight gain, feed consumption and feed conversion ratio in broilers irrespective of the system of housing. The broilers reared in environmentally controlled housing system had comparatively higher body weight (2022.19g Vs 1819.25g) and better feed conversion ratio (1.37 Vs 1.47) than the open sided housing system. The housing systems and feeding plans in this study also had significantly influenced the body weight gain, feed consumption and feed conversion ratio, which are all favourable in environmentally controlled housing system.