Figure 4.34 Effect of natural cooling

 Infiltration is the flow of outdoor air into a building through cracks and other unintentional openings. Infiltration is also known as ‘air leakage’ into a building.”

The ventilation and infiltration must be controlled in order to provide the required thermal comfort and indoor air quality to building occupants. A person needs 10 liters of air per second (0.01m3/s or 0.6 m3/minute) and if less air is provided then the building will have indoor air quality issues. The outbreak of the COVID-19 pandemic, stresses even more the need for adequate natural ventilation.

The need for fresh air can be expressed by a unit called air exchange per hour, which represents the number of times all air within a building is being exchanged with outside air over the course of an hour.

Further we will see how do we shape the building in order to actually get the air exchanges per minute as required.

Depending on the climate, natural ventilation can contribute to 10–30% cooling energy savings. Studies in Chinese climate, show savings of 50-60% in cooling. According to other studies, the effect of the natural ventilation on decreasing the cooling load in appartments is shown in Figure below. The appartments have different orientation and those to the west and southwest have the largest cooling demand, which can be decreased up to 80% by using natural ventilation.

Figure 4.13Effect of natural cooling

The airflow in the building is dependent on the wall layout, openings position, their size, furniture and similar. Straight flow provides the speediest movement, while any obstacles in the interior can cut air speeds markedly. The internal spaces can be zoned in order to maximize the potential use of natural wind forces for natural ventilation.