Water heating in Brazilian residential buildings: a comparison between electric showers and solar heating

Abstract This study compares electricity consumption between solar water heating systems and electric showers in twelve bioclimatic zones in Brazil. Solar heating was assessed using the simplified and detailed methods of INMETRO's Normative Instruction for Residential Buildings (INI-R) and the Energy Plus programme. At the same time, electric showers were analysed using programming routines. Annual energy consumption for water heating varied between 143 and 1825 kWh for electric showers and between 0 and 539 kWh for solar heating systems, with differences in the results depending on the methodology used for evaluation. The economic viability of solar heating depends on the climate and the local energy tariff, being advantageous only in Canela, Vitória da Conquista, Brasília, Rio de Janeiro, Goiânia and Cuiabá. The study highlights the need for more research on the subject and recommends that INMETRO reconsiders adopting the simplified method, as it presents more favourable results for certification than the detailed method.