Solar hot water (SHW) experiments in social housing are creating a new model for urban infrastructure and energy provision in the State of Sao Paulo, Brazil. This chapter is based on the experience of the Housing and Urban Development Company Companhia de Desenvolvimento Habitacional e Urbano (CDHU) of the State of Sao Paulo in promoting the use of SHW in its dwellings. Although Brazil's electricity generation is largely based on hydropower, SHW is seen by both the State and the municipality as playing a relevant role in their carbon reduction strategies. The chapter analyses the interaction between the social and material agencies involved in achieving low carbon in the city. SHW systems, by offering a renewable energy solution that could reduce GHG emissions while also replacing electric showers and addressing peak demand, appeared to provide a solution for many of Brazil's electricity problems.