Savings related to solar water heating system: A case study of low-income families in Brazil

Abstract The inclusion of solar water heaters available through subsidies of the Brazilian government has benefited more than 300,000 low-income families. Although these subsidies are important for wide implementation of this technology, the actual system performance is unclear. Moreover, it is unclear whether the performance is affected by user behavior in the context of complex socioeconomic issues. The objective of this research is to assess the influence of human behavior on the potential savings induced by solar water heaters. The research strategy integrated qualitative and quantitative measurements. We applied the cluster analysis technique to identify five homogeneous subgroups for a case study in Londrina, Brazil, in which a detailed measurement procedure was implemented to gather data on these subgroups over one year. The measurements were conducted to gain a better understanding of the factors affecting electricity consumed by showering. This study shows that the benefits of solar heaters vary according to the user and use of the technology. The annual energy savings averaged 9.51–18.6 kWh per person. A lack of technological understanding and the difficulty in effectively mixing hot and cold water were the main factors contributing to the inefficient use of the system.