The wind speed in solar greenhouse with natural ventilation is very low (0.01–0.2 m s−1), which may result in much higher aerodynamic resistance values (20,800–1040 s m−1). Fernndez et al.(2010, 2011) reported that the FAO 56 Penman–Monteith equation with a fixed aerodynamic resistance of 295 s m−1 can better estimate daily ET0 in greenhouse: