Maintaining airtightness in a building is essential for enhancing energy efficiency, thermal comfort, and indoor air quality. To ensure airtightness over time, meticulously seal the building envelope using flexible caulks and sealants, and improve window and door seals with draught-proofing strips. Properly sealing HVAC duct penetrations and insulating wall and ceiling breaches also contribute to reducing air leakage. Regular maintenance inspections, along with professional consultations, can help balance airtightness with effective ventilation, preventing the build-up of indoor pollutants and ensuring a healthier living environment.