A building retrofit involves upgrading or modifying existing buildings to improve their performance and adapt to modern technologies. Retrofitting can encompass a wide range of changes, from enhancing energy efficiency with updated HVAC systems and insulation to incorporating renewable energy technologies like solar panels. Energy-efficient retrofits are particularly impactful for older buildings, reducing operational costs and carbon footprints. Federal programs, such as those led by the Office of Energy Efficiency & Renewable Energy, support retrofitting efforts by offering grants and guidance. Retrofitting not only extends the lifespan of buildings but also contributes to meeting sustainability goals and compliance with evolving building codes