However, many factors must be taken into account in order to achieve the optimum system. The size of the house, the air tightness of the building, and the type/size of the system required to meet both the needs of the house and the wants of the customer are all issues to consider. The type of equipment to be installed (including controls), the commissioning of the system, and maintenance of the installed equipment also must be considered key factors for achieving the desired result.

Mechanical ventilation systems can range from a bathroom fan with a small, simple duct system and an on-off switch as a control up to a fully ducted heat recovery ventilation/enthalpy recovery ventilation (HRV/ERV) system with a relatively complex duct system and multiple controls. All systems require proper design, installation, and maintenance, or chances are they will not work properly.