Reducing energy consumption in buildings also can be referred to it as increasing the energy efficiency in a building. This study aims to examine the energy performance of buildings in North Cyprus. Three different case studies have been taken into consideration from North Cyprus: a normal villa without any renewable system, a flat with no renewable system, and a villa with a solar system for electricity generation. The energy efficiency of the buildings is evaluated using alternative clean energy systems such as photovoltaic systems. The founding of this study indicates a payback period of 4.5 years for the installation cost of the energy system. Using materials for minimizing the energy consumption in the buildings for example using insulation materials in the construction of a building will reduce the consumption of energy for cooling and heating. The case studies were simulated using SAM software and the obtained results have been compared. The environmental impact has been also taken into consideration where the effect of transforming buildings into sustainable ones is studied and how it would affect the numbers of the carbon footprints in buildings. The study found that the cost difference between insulating walls optimally and not insulating them at all is approximately 6000 euros. The payback period for this investment would be approximately 9 years. The research also calculated the amount of CO2 emissions, finding that a villa would emit 2154 tons and a flat would emit 1675 tons per month. Increasing energy efficiency in buildings is a fast, cost-effective, and environmentally friendly way to reduce energy consumption.