Review of free cooling system using phase change material for building

• Free cooling application by means of PCMs is a ventilation method in building which is working properly in the climatic conditions where diurnal temperature is 12–15 °C.
• Replacing a conventional air condition unit with free cooling system can decrease the CO2 emissions by 430 ton per year.
• Melting point of PCMs is a critical factor in the design of the storage unit.
• Melting point of PCM is estimated in the range of 20–26 °C in order to maintain melting point and designed room temperature as close as possible.

Buildings are responsible for 40% of our nation's total annual energy consumption and for one-third of our greenhouse gas emissions. These greenhouse gases are the cause of global warming. Lighting, heating, cooling, and air conditioning are all heavy energy consumers. Interestingly, advances in the understanding of the environmental effects of greenhouse gas emissions have led to a rise in the use of environmentally friendly cooling and heating systems in buildings. Free cooling systems rely on phase change materials that absorb heat from indoors during the day and then release it outdoors during the night.The investigations undertake by different researchers will be explained in this article. Phase change materials, climate applicability, feasibility analysis, and factors affecting the charging and discharging are discussed briefly. The reduction in CO2 emissions resulting from the application of free cooling systems to buildings is also discussed.