page_title: Passive cooling
section_title: Ventilation
hierarchical_section_title: Passive cooling / Modulation and heat dissipation techniques / Ventilation
context_page_description: Passive cooling is a building design approach that focuses on heat gain control and heat dissipation in a building in order to improve the indoor thermal comfort with low or no energy consumption. This approach works either by preventing heat from entering the interior or by removing heat from the building. Natural cooling utilizes on-site energy, available from the natural environment, combined with the architectural design of building components, rather than mechanical systems to dissipate heat. Therefore, natural cooling depends not only on the architectural design of the building but on how the site's natural resources are used as heat sinks. Examples of on-site heat sinks are the upper atmosphere, the outdoor air, and the earth/soil.
context_section_description: Ventilation as a natural cooling strategy uses the physical properties of air to remove heat or provide cooling to occupants.  In select cases, ventilation can be used to cool the building structure, which subsequently may serve as a heat sink.
  Cross ventilation - The strategy of cross ventilation relies on wind to pass through the building for the purpose of cooling the occupants. Cross ventilation requires openings on two sides of the space, called the inlet and outlet. The sizing and placement of the ventilation inlets and outlets will determine the direction and velocity of cross ventilation through the building. Generally, an equal (or greater) area of outlet openings must also be provided to provide adequate cross ventilation.
  Stack ventilation - Cross ventilation is an effective cooling strategy, however, wind is an unreliable resource. Stack ventilation is an alternative design strategy that relies on the buoyancy of warm air to rise and exit through openings located at ceiling height. Cooler outside air replaces the rising warm air through carefully designed inlets placed near the floor.
  One specific application of natural ventilation is night flushing.
caption: A pair of short windcatchers or malqaf used in traditional architecture; wind is forced down on the windward side and leaves on the leeward side (cross-ventilation). In the absence of wind, the circulation my be driven with evaporative cooling in the inlet. In the center, a shuksheika (roof lantern vent), used to shade the qa'a below while allowing hot air rise out of it (stack effect).[11]