A well-designed return air strategy is essential for the performance of the HVAC system in an energy-efficient house with lower airflow requirements to meet the load. The return air must “see” a clear path from every room that has a supply outlet, except bathrooms or kitchens due to the potential for spreading odours through the house. A direct return from each room to the equipment is not desirable when trying to minimize duct lengths and pressure losses in the return system. Rooms without proper return air path tend to become pressurized, which will impede supply airflow and could result in comfort complaints. The usual door undercuts do not allow adequate return volume and are not appropriate for an energy-efficient house. Low resistance in the return air path has less than 0.05-inch water column (iwc) pressure loss. The pressure loss for a filter at the return grille must also be considered in the return air stream. The value for return capacity is two times the volume of the total supply air with an airflow velocity within the return at less than 500 feet per minute and the net free area that is sized 1.5 times the cross-sectional area of the return duct. The central return strategy is the simplest and effective way to get air back to the air handler. Each room that has a door to close it off from the central space except for the laundry and the hall both utilize an over-the-door method to transfer from that room back to the central return. turn, it Even with the proper net free area and sizing of the return duct, airflow can be restricted by turbulent air at the entrance of the return duct, causing poor performance and noise issues should be placed in a central hallway where it is adjacent to the main living space of the house. The selection and placement of the supply air outlets are essential to provide comfort in the space. The air must be delivered in a manner that mixes the supply air with the room air without introducing unacceptable noise or causing the sensation of a draft on the occupant. The distribution of air in the room is the function of the shape and size of the air outlet. At the same time, the placement of the air outlet is as important to the comfort in the room as is the type of air outlet that is selected.