Buildings contribute significantly to global carbon emissions, with heating, ventilation and air conditioning (HVAC) system being the primary energy consumer within these structures. This study delved into the potential for energy conservation and carbon emission reduction through the installation of energy-efficient air filters in building ventilation systems. The findings were corroborated through measurements conducted on an air handling unit (AHU) within a commercial building. Adhering to the International Performance Measurement and Verification Protocol (IPMVP) option A for Retrofit Isolation on key parameters, the study demonstrated that the AHU, by retrofitting energy-efficient air filters to replace the conventional filters, managed to decrease its fan motor power by 23.4% while maintaining consistent airflow output. Taking into account the operational hours of the commercial building, this modification translated to a saving of 1792.83 kWh of electrical power and a reduction of 0.7 tonne of carbon emissions annually for that single AHU. Extrapolating these results to a broader, global scale, it is estimated that retrofitting energy-efficient air filters could contribute to an annual carbon reduction of 0.112–0.225 Gt. This research underscores the substantial energy efficiency and environmental benefits attainable through the adoption of energy-efficient air filters in AHUs within building ventilation systems.