Ventilation is another element that influences thermal comfort, health, and productivity. A mechanical ventilation system can be used to aggressively introduce fresh outdoor air into a structure or deliver it naturally by doing nothing at all. In the first scenario, which is typical in residential buildings, the required ventilation is provided through leaks and cracks that allow air to enter the living area, as well as by opening windows and doors. Air vents with dampers or exhaust fans give the extra ventilation that is required in the bathrooms and kitchens. However, with such unregulated ventilation, the fresh air supply will either be excessively high, squandering energy, or excessively low, resulting in poor indoor air quality. Due to the lack of a public outcry regarding energy waste or air quality, the current practice is unlikely to alter for residential structures, and it is challenging to justify the expense and complexity of mechanical ventilation systems.
Any heating and cooling system in commercial buildings includes mechanical ventilation systems, which supply the necessary volume of outside air and disperse it evenly throughout the structure. This is hardly surprising considering the reliance on mechanical ventilation in many rooms in large commercial buildings that lack windows. Since most buildings’ windows are hermetically sealed and cannot be opened, even the rooms with windows are in the same predicament. To be on the “safe side,” it is not a good idea to oversize the ventilation system because expelling the heated or cooled inside air uses energy. To keep indoor air quality at acceptable levels, it is also important to avoid reducing ventilation rates below the necessary minimum in order to save energy. The table lists the minimal fresh air ventilation requirements. The figures assume that CO2 and other contaminants can be controlled with a sufficient margin of safety, which calls for each person to receive at least 7.5 L/s of fresh air.
The mechanical ventilation system also filters the air as it enters the building to clean it. For this use, various filter types are available depending on the required levels of cleanliness and the permitted pressure drop.
This is actually part-5 of the HUMAN BODY AND THERMAL COMFORT series. part-4 is given in the link below.
Part-3: Cold adaptation in humans.
Part-2: Thermal comfort in buildings.