Authors : Okonkwo, B. U.; Nwufo O. C.; Nwaji, G. N.; Okoronkwo, C. A.; Anyanwu, E. E.

Volume/Issue : Volume 10 - 2025, Issue 11 - November

Google Scholar : https://tinyurl.com/393yzhpm

Scribd : https://tinyurl.com/ykwzxbv8

DOI : https://doi.org/10.38124/ijisrt/25nov798

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Abstract : The global building sector, a major energy consumer, urgently requires decarbonization solutions that are not only technically effective but also economically viable and environmentally sustainable. This is particularly critical in tropical developing nations, where rising cooling demands, fragile electricity grids, and waste management challenges converge. This study presents a comprehensive techno-economic and environmental (TEE) assessment of a novel hybrid Solar Collector/Nocturnal Radiative Cooling (SCN/R) system, engineered for this specific context. The system's core innovation is a spectrally selective coating fabricated from upcycled Polyethylene Terephthalate (PET) plastic waste, integrating circular economy principles directly into its design. Based on empirical data from a prototype in Nigeria, the system demonstrated robust 24-hour passive operation, achieving a solar thermal efficiency of 47.11% and a nocturnal cooling power of 196.86 W/m2. While the achievable temperature differentials position it as a supplementary pre-conditioning system rather than a full HVAC replacement, its economic potential is pronounced. Strategic utilization of local materials and valorized waste resulted in an exceptionally low capital expenditure (CapEx) of approximately ₦1,800,000 for a 3.63 m2 unit. A conservative payback period analysis, accounting for displaced electricity for water heating and partial cooling, yields a compelling 6.7 to 8.9 years. Environmentally, the system offers a triple benefit: significant operational carbon mitigation (0.6-0.7 tonnes of CO2-eq annually), diversion of plastic waste from landfills, and the complete avoidance of high-GWP synthetic refrigerants. We conclusively assert that this SCN/R system represents a viable and synergistic solution for sustainable building thermal management in the tropics. To unlock its full potential, we recommend design hybridization with heat pumps and advocate for policy frameworks that include carbon financing and green building standards, thereby accelerating its adoption as a cornerstone technology for a low-carbon, circular built environment.

Keywords : Techno-Economic Analysis; Life Cycle Assessment; Hybrid Solar System; Nocturnal Radiative Cooling; Circular Economy; Payback Period; Carbon Mitigation; Sustainable Development; Policy Frameworks.

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