▎ 摘　　要

Energy management in a building is to control and lessen the energy consumption, to decrease both costs and carbon emissions. Building-integrated thermal systems are adept to produce heat. Various scenarios have been planned to integrate heat into a building formation to enhance performance of entity system, supply indoor heating, and provide hot water. Concept backside Flat-plate Solar collector is that Sun warmth the set of tubes. This surface collects as much energy as preferable, and then water heats by this energy. This study aims to compare the Energy efficiency between phase change materials (PCMs) containing Paraffin-wax/Graphene and Paraffinwax/Graphene Oxide carbon-based nanofluids for renewable, clean, green and sustainable energy systems such as Flat Plate Solar Collectors by applying these PCMs in Buildings heating systems. Results showed that, Thermal conductivity of both Graphene/P-wax and Graphene Oxide/P-wax was enhanced in comparison with Paraffin. Also, trend of Graphene showed better thermal performance.