Currently, buildings are considered to be a continuously evolving organism that over time has to be treated, rehabilitated, and upgraded to meet the requirements set by the user at a certain stage. Buildings are a central element of the EU member states' energy efficiency policies, accounting for about 40% of final energy consumption, and 36% of greenhouse gas emissions, and about 75% of buildings are not energy efficient. Recent applications and studies establish that green retrofitting has maintained older existing buildings to increase energy efficiency, optimize building performance, increase occupants' satisfaction, and boost economic return while decreasing greenhouse gas emissions. In this regard, this chapter aims to address the main factors that negatively affect the performance of residential buildings and presents the common green retrofitting measures that can be taken to ensure the state of human well-being in residential buildings.