Heating, ventilation, and air conditioning (HVAC) systems are significant consumers of end-energy use in non-domestic buildings. Mechanical ventilation is used to maintain optimum indoor air quality (IAQ) and thermal comfort by supplying conditioned fresh air to indoor environments. In this process, filtration methods are used inside an air handling unit (AHU) to remove particulate matter (PM) from ambient air, but concerns remain between pollutants escaping filtration based on the filter grade along with a high operational carbon footprint. This study investigates the potential of green infrastructure (GI) to act as a PM control mechanism, improving the filtration system operations by reducing PM intake and addressing increasing energy consumption usage as the filters become loaded. Three field tests were conducted using a combination of different GI types (Azalea Japonica, Carex Grass and Kolibri Ivy) positioned at the AHU fresh air inlet. The system pressure was monitored, filters weighed, and a microscopic image analysis performed. The GI was found to act as a natural filter, reducing the levels of particulate matter entering the AHU and extended the filter lifetime. The results demonstrated appreciable energy, economic, and carbon reductions with savings of up to 7.2%. The combination of Carex Grass and Kolibry Ivy led to the most significant savings while the Azalea Japonica suffered from excessive leave loss and subsequent deposition on the filters. Specifically, the result show for a porous barrier installed at the AHU inlet to be effective, the plants should not be brittle, nor suffer from high leaf loss, have lower moisture requirements and a high leaf area density. The integration of GI offers a promising approach to address the challenges of sustainably improving energy consumption in mechanically buildings without compromising IAQ.