Energy demand is a global crisis. Since the year 2010, most buildings’ energy consumption across the globe has increased by almost 14% (Paris Agreement, 2018). As a result, energy-supplying utilities have had to increase the burning of coal and gas to meet the demand, which results in high carbon emissions causing global warming (EcoMetrix Africa, 2021). This study evaluates the impact of implementing smart technologies in high-density residential zones by utilising a system that is energy-efficient and cost-saving. The study compared the energy consumption of two mixed student residences of the University of Johannesburg, where one is equipped with smart technologies while the other functions with a traditional energy supply system. The results obtained show that there is a 46.26% variance between the two residences' energy consumption. This study's results show that the implementation of smart technologies in high-density residential units can reduce energy consumption by approximately 46% compared to a traditional way of energy supply. The results also reveal that the implementation of smart technologies can reduce the contribution of carbon emissions by 33%.