Passive alternatives to mechanical air conditioning of building: A review

Human comfort is gaining importance in the recent decades. Mechanical air conditioners are conventional means of creating thermal comfort but they are energy intensive and hence harmful to ecological system. Therefore passive cooling can be adopted as a viable alternative to conventional cooling system. This paper reviews various passive cooling options available such as nocturnal radiation, geothermal, ventilation, evaporative, hydrogeothermal, deep ocean/lake, thermal insulation and shading along with their advantages, limitations, working principles and climatic dependence. The mathematical equations used for computing the performance of passive cooling systems have been discussed along with design and environmental parameters influencing the systems' performance. The usefulness of phase change materials, thermal mass and radiant cooling in passive cooling systems is also examined. Case studies containing experimental data and numerical predictions are discussed to provide options for building architects and infrastructure developers to adopt the appropriate passive cooling strategy. In addition, issues related to occupants' health and indoor air quality are also explained. A brief review of energy-efficient and eco-friendly solar cooling systems is also included. (C) 2013 Elsevier Ltd. All rights reserved.