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Top1. Introduction
The population is growing exponentially as global food demand is rising. Food production will need to be doubled by 2050, to meet the United Nation’s Millennium Development Goals on hunger. This needs to be achieved in the world where suitable agricultural land is limited. Globally, available per-capita cropland is now about 0.23 hectare (Pimentel and Wilson, 2004). Protected farming can be adopted in locations where the soil is not favorable for a desired crop. The technology can be also adopted in roof-top farming and in areas with limited space like urban areas (MIT, 2014). Protected farming method was invented by William Frederick Gericke, who was a professor at the University of California Berkeley, in the 1930s (Thanet Earth, 2014). Growing food within cities at the doorstep of the consumers eliminate the need for transport, thereby reduces greenhouse gas emissions and food-waste (Despommier, 2009). The major agricultural problems caused in open field farming such as, pesticides, pests, deforestation, and soil erosion would be nearly non-existent because of controlled farming (Han, 2014). The Protected farming provides protection to the crops from extreme weather occurrences and eliminates the use of mechanical plows thus reduces the burning of fossil fuel. The method reduces the occupational hazards such as accidents in handling farming equipment in case of open field agriculture. Approximately 70% water is saved in comparison to open field farming (Bareja, 2011). Energy consumption in protected farming structure is depends upon the four indicators viz. water pumping, light supplement, CO2 balancing and heating / cooling. These four indicators are directly depends upon the three criteria viz., cropping area, daily crop water requirement and indoor environment of the surrounding. The chief cause for applying micro-climate control in protected crop growing structure is to achieve optimal growing environment. Automatic control system inside the protected farm monitors the substrate moisture content; light intensity, carbon dioxide concentrations and air temperature are maintained at optimal level for maximum crop growth. Various types of control system like thermostats, step-controllers, dedicated microprocessors, and computers are generally used in protected farm structure for precise monitoring of these indicators. A computer control system can provide fully integrated control of irrigation with fertilization, light intensity, carbon dioxide concentrations and temperature in a protected farming structure. Water is applied to the crops just before the initial moisture stress occurs through either misting or spraying or dripping using solar or grid powered motorized pump (Grundfos, 2009). Supplementary light (400 to 700 nanometer wave band) inside a protected farm is provided for optimal photosynthesis on the green part of the plant by using LED bulbs (Brown, 2012). Carbon dioxide content in air in a protected farm is maintained (350ppm to 700 ppm) artificially using motorized side wall louvered fans (Hellickson and Walker, 1983). Protected farming requires cooling systems whenever the daily average temperature is too high for the crops to function properly using fogging or evaporative wet-pads pad and ventilating fans (Helmy et al., 2013). Artificial heat is necessary to maintain favorable temperatures in a protected farm during winter using either steam or hot water with centralized heating system. The degree of heating depends upon the amount of heat loss from the protected structure (Amanda Williams, 2017). No specific algorithm is available for minimizing energy consumption in a protected farm which would lead saving in power and operating cost. In this paper an attempt has been made to estimate minimize energy consumption index for a single story protected farm located in the vicinity of National Institute of Technology Agartala, India comparatively using bacteria foraging (BFO) algorithm and Group Method of Data Handling (GMDH) algorithm.