The construction industry's thirst for power has skyrocketed on a global scale. A significant amount of this power is used for buildings' heating, ventilation, and air-conditioning needs (HVAC systems), which in turn ensure occupants' comfort. A sustainable future requires more zero-energy or green buildings to meet the massive global energy demand. This study explores the possibility of reducing air conditioning expenses while taking into account various roof systems referring to sheet panels integrated with thermal insulation or a phase change material. Within the context of the current investigation, four sheet panels made of acrylic, aluminium, galvanized iron, and polycarbonate were examined. In addition, aforementioned sheet panels were filled with either polyurethane (PUR) foam insulation or a form-stable phase change material of FS29, an organic and inorganic mixture. In order to ascertain the thermo-physical properties of FS29 PCM (in both its solid and liquid phases), as well as its latent heat, experiments were carried out. According to the findings, the roof with the acrylic PCM integrated roof (ACPIR) succeeds in the best annual air conditioning or energy cost savings (7.90 and 8.18 $/m2/year), the highest carbon emission mitigations (144.15 and 156.44 kg-CO2/year) and the shortest payback period (9 and 8.7 years), for India's composite and warm-humid climatic conditions.