An Appraisal of the Design Sustainability of Solar Water Heating Systems Via Cosine Similarity Index

This study aimed to assess the sustainability of solar water heating systems (SWHSs) to identify the sustainability indicators necessary for improvement. It involves the development of a fuzzified multi-criteria decision model (MCDM) using cosine similarity index for the sustainability assessment of SWHSs namely; integrated collector storage (ICS), thermosyphon (TS), active open-loop (AOL) and active closed-loop (ACL). The article was able to identify the indicators necessary for improvement following the sustainability assessment of SWHSs in domestic and industrial applications. The framework for the sustainability assessment of the SWHSs included the traditional sustainability indicators such as economic (EC), environmental (EN), and social (SO), and peculiar sustainability indicators namely manufacturing (MA), maintenance (MN), reliability (RE), and life-cycle (LC). This study employed conceptual design developed based on working principle of SWHSs and responses of design experts for sustainability data. For future research, practical evaluation, and more sustainability indicators is recommended for increased analysis depth on the sustainability of the systems. The establishment of sustainability indicators and sub-indicators towards the assessment of SWHSs using MCDM considering the indicators identified for the benefit of energy planning from the manufacturer to the end user. This research focus is on sustainability using the computational strength of the fuzzified MCDM method to assess the sustainability of SWHSs using traditional and peculiar sustainability indicators. The highest economic indicator was in ACL at 53% and the lowest in TS at 42%. This shows that it is important for sustainable economic ease and growth, across the domestic and importantly the industrial sector that the rate of heating using SWHSs should be improved for economic sustainability. The highest environmental indicator was in ICS at 54% and the lowest in TS at 39%. The social indicator was highest in ICS with 43% and joint lowest in TS and AOL at 30%.