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A new parameter has been defined in this paper in order to compare the performance of the closed greenhouse concept in different configurations - the Surplus Energy Ratio showing the available excess thermal energy that can be stored in the TES system and the annual heating demand of the greenhouse. The closed greenhouse is compared with a conventional greenhouse using a case study to guide the energy analysis and verify the model. A theoretical model has been derived to evaluate the performance of various design scenarios. In order to utilize the excess heat at a later time, long- and/or short-term thermal storage technology (TES) should be integrated. Therefore, the excess heat must be removed by other means. In an ideal fully closed greenhouse, there is no ventilation window. In principle, it is designed to maximize the utilization of solar energy by use of seasonal storage. The closed greenhouse can be considered as the largest commercial solar building. The closed greenhouse concept has been studied in this paper. 1256-1266 Article in journal (Refereed) Published Abstract This cost is then used to calculate the present worth (PW) of the operation considering the life span of the greenhouse, the annual increase in the fuel costs, and the historical inflation.2013 (English) In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. The costs regarding the use of electricity and fuel are determined at the end of each typical meteorological year. The electric system considers both heating and cooling using electricity, whereas the combined system considers an electric cooling and LP gas for heating. The total cost includes the maintenance and operation expenses, where the operation cost is affected directly by the amount of energy used to power the air conditioning equipment (heating and cooling), for which two systems were considered: electric and combined.
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The investment cost considers installation and materials costs, including the structure and different covers for each different greenhouse shape. It is possible to design several systems that would deliver an expected service nevertheless, the investment, maintenance, and operation costs of every design will vary from one design to another. Nevertheless, this approach is no longer valid when trying to accomplish energy efficiency at its best, as the usage of such temperatures typically would result in the overestimation of energetic needs for the studied greenhouse. These temperatures attempt to reflect the climatic conditions with maximum and minimum values. Nevertheless, conventional calculation approaches consider vague temperature values, for example: mean temperature of the hottest month, mean temperature of the daily maximums of the hottest month, annual maximum temperature, mean temperature of the coldest month, mean temperature of the daily minimums of the coldest month, annual minimum temperature, etcetera. However, the outdoor temperature is one of the central parameters to examine. To calculate the energetic needs of a greenhouse, maximum solar radiation availability, outdoor temperature, humidity, wind speed, and direction are important variables to consider. Since temperature influences the growth and development of the plants, it is the main parameter to control inside greenhouses. McCartney & Lefsrud (2018) studied protected agriculture in tropical, polar, and urban conditions and concluded that there are several challenges regarding the implementation of efficient heating and cooling systems, accessibility of technologies, automation, and the efficient use of water resources. To conclude, qualified human resources, as well as applied technology, are notorious weaknesses found in the report, which analyzes agro-environmental policies in Brazil, Chile, Colombia, Mexico, and Nicaragua. In this FAO report, the identified weak points of climate-smart agriculture are an absence of strategic planning and a high deficiency in logistics, transportation, automated production and, lastly, the most pertinent to this investigation: energy management. This program boosts sustainable agriculture, increasing resilience and productivity, including the mitigation of greenhouse emission gases apart from achieving food security and rural development ( FAO, 2014). The FAO drives an intensive program on climate-smart agriculture.