Airtightness testing is an essential process for evaluating and improving the energy efficiency of buildings, mandated by UK Building Regulations to ensure reduced energy consumption and environmental impact. Using methods like the blower door test, it measures air leakage, identifying problematic areas that lead to unwanted heat loss, increased heating bills, and discomfort for occupants. Addressing these leaks not only enhances energy performance and occupant comfort but also lowers the building's carbon footprint. Furthermore, integrating airtightness data into Energy Performance Certificates (EPCs) provides a more accurate reflection of a building's energy efficiency, aiding in compliance and informed energy-saving decisions.