Understanding the environmental impact of residential electricity consumption in Brazil: integrating top-down and bottom-up approaches with Life Cycle Assessment

Abstract

Whole Building Life Cycle Assessment (WBLCA) has been a topic of great interest in recent years. It has been used to find solutions to reduce the environmental impacts of construction and help achieve carbon emission reduction targets. In Brazil, electricity consumption in the residential building stock represents a large portion of national electricity. Therefore, this study evaluates the environmental impacts of the operational electricity use of buildings by conducting a Life Cycle Assessment (LCA) of households' electricity consumption estimates in Brazil. Inter-annual and inter-regional variations in electricity consumption were assessed and incorporated into the LCA methodology. Quantification and characterisation were done using top-down and bottom-up methodologies to delimit the electricity consumption of residential buildings. Subsequently, the current and future electricity matrices were detailed and modelled using OpenLCA software. Two functional units were then evaluated: the climate change indicator impacts of the entire building stock and the average impact per housing unit in each region of Brazil. Regarding the “climate change” indicator, a probabilistic impact of between 18 and 32 MtCO_2-eq/year is estimated for the entire building stock and between 228.5 and 766.4 kgCO_2-eq/HU/year depending on the region, the electricity consumption of the dwelling and the electricity matrix considered. Bottom-up analysis showed that despite regional variations, appliances such as refrigerators and electric showers are the significant contributors to CO_2-eq emissions and should, therefore, be the focus of policy interventions. The main innovation of this research is the integration of bottom-up and top-down analysis within WBLCA in Brazil, thus highlighting the differences among different regions and appliances within household's environmental impacts. This research introduces a replicable and innovative method to assess probabilistic electricity consumption impacts in the use phase of buildings, accounting for uncertainties and offering a range of possible outcomes for future studies.