Greenhouses are crucial for maintaining an ideal temperature and humidity level for plant growth; however, attaining ideal levels remains a challenge. Energy-efficient and sustainable alternatives are needed because traditional temperature/humidity control practices and vapor compression air conditioning systems depend on climate conditions and harmful refrigerants. Advanced alternative technologies like evaporative cooling and desiccant dehumidification have emerged that maintain the ideal greenhouse temperature and humidity while using the least amount of energy. This study reviews direct evaporative cooling, indirect evaporative cooling, and Maisotsenko-cycle evaporative cooling (MEC) systems and solid and liquid desiccant dehumidification systems. In addition, integrated desiccant and evaporative cooling systems and hybrid systems are reviewed in this study. The results show that the MEC system effectively reduces the ambient temperature up to the ideal range while maintaining the humidity ratio, and both dehumidification systems effectively reduce the humidity level and improve evaporative cooling efficiency. The integrated systems and hybrid systems have the ability to increase energy efficiency and controlled climatic stability in greenhouses. Regular maintenance, initial system cost, economic feasibility, and system scalability are significant challenges to implement these advanced temperature and humidity control systems for greenhouses. These findings will assist agricultural practitioners, engineers, and researchers in seeking alternate efficient cooling methods for greenhouse applications. Future research directions are suggested to manufacture high-efficiency, low-energy consumption, and efficient greenhouse temperature control systems while considering the present challenges.

Evaporative cooling systems have evolved as highly effective greenhouse-control solutions, particularly in hot and dry places such as Multan, Pakistan. This chapter evaluates the performance of direct (DEC) and indirect evaporative cooling systems (IEC) for an asymmetric greenhouse using TRNSYS software. The performance of the systems was assessed in terms of simulated ideal vapor pressure deficit (VPD), temperature, and humidity for tomato cultivation. According to the results, the DEC system effectively reduced the temperature, while the IEC system effectively managed the humidity. The DEC system showed maximum energy saving of up to 40% in hot and dry months. The combination of both DEC and IEC systems produced the optimum level of temperature and humidity for increased tomato output, energy savings, and water usage efficiency. A higher (up to 0.35 kg/h) evapotranspiration mass flow rate was observed in the middle of the year in the case of the second and fourth system configurations. Findings from this study highlight the need for sustainable, energy-efficient cooling methods for greenhouse agriculture.