Passive cooling

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 (heat gain prevention) or by removing heat from the building (natural cooling). Natural cooling utilizes on-site energy, available from the natural environment, combined with the architectural design of building components (e.g. building envelope), 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 (i.e. everything that absorbs or dissipates heat). Examples of on-site heat sinks are the upper atmosphere (night sky), the outdoor air (wind), and the earth/soil. Passive cooling is an important tool for design of buildings for climate change adaptation - reducing dependency on energy-intensive air conditioning in warming environments. Passive cooling covers all natural processes and techniques of heat dissipation and modulation without the use of energy. Some authors consider that minor and simple mechanical systems (e.g. pumps and economizers) can be integrated in passive cooling techniques, as long they are used to enhance the effectiveness of the natural cooling process. Such applications are also called 'hybrid cooling systems'. The techniques for passive cooling can be grouped in two main categories: Preventive techniques that aim to provide protection and/or prevention of external and internal heat gains. Modulation and heat dissipation techniques that allow the building to store and dissipate heat gain through the transfer of heat from heat sinks to the climate. This technique can be the result of thermal mass or natural cooling. Protection from or prevention of heat gains encompasses all the design techniques that minimizes the impact of solar heat gains through the building's envelope and of internal heat gains that is generated inside the building due occupancy and equipment.