The adoption of renewable energy technologies has gained traction over the recent years, many countries are heeding the call to migrate from energy sources which have been found to be harmful to the environment and adopt sustainable energy generation practices. This has led to many countries developing energy policy frameworks that outline the transition strategy from fossil fuel-based energy to clean and renewable energy and the ultimate decarbonisation of energy generation. These policy frameworks are often decade long millennium policies, and most are reaching their deadline target goals soon. The primary energy of buildings comprises a substantial amount of the overall energy primary energy and hence efforts are being made to adopt sustainable energy resources to help reduce contribution of Greenhouse gas and CO2 emissions by buildings. The development of solar energy technologies has placed solar energy as an affordable and popular choice among the available renewable energy resources. The two key solar energy technologies used for heating and electricity generation are Solar Collectors and Solar Photovoltaics respectively. This thesis project evaluates and compares the policy framework of the EU, Hungary and Republic of South Africa concerning renewable energy, particularly solar energy. A climate analysis is conducted to ascertain available solar energy resources making use of the PVGIS tool. An analysis of the building stock is also conducted to determine the building typologies and classifications and lastly the primary energy demand analysis per building type is evaluated using tools such as the Tabular and Episcope database webtools. A methodology is derived in order to estimate the proportion of primary energy demand that can be replaced by the two solar energy technologies (solar collectors and PV systems) for heating and electricity generation. The methodology is based on the data inputs of the climate, building stock and primary energy analysis and incorporates a methodology derived by Kalschmitt for computing available and usable rooftop area. Using the methodology developed, it estimated the primary energy replacement share is about 16% across the different building types in Budapest with a potential energy generation of 3000 GWh/year from the solar energy technologies combined for rooftop utilisation.