Information and communication technologies are believed to contribute to reduce environmental impacts in other economic sectors. Smart homes aim to this purpose through improved resource management, but actual environmental benefits are uncertain. Indeed, an increase in efficiency may lead to an increase in consumption and thus in environmental impacts, a phenomenon called rebound effect. Here we describe an agent-based approach which simulates human behaviors during the use phase of smart homes and allows computation of environmental impacts including those due to rebound effect. In our simulation, smart homes reduce environmental impact by 2%. However, rebound dims between 6% to 24% of the smart homes' environmental benefits depending on impact category. Moreover, a sensitivity analysis indicates that weather and electricity mix variability should be considered when designing policies related to smart homes technology. Life cycle assessment by this method accounts for user behaviors, which is necessary when studying some complex systems found in sustainable consumption. Evaluate the environmental performance of a smart-city and study different rebound mechanisms are possible applications of the developed approach.