Solar greenhouses: Climates, glass selection, and plant well-being

•Worldwide mapping of the thermal behaviour of solar greenhouses by varying glasses.•Operative temperature in the free-floating regime to control the indoor microclimate.•In tropical/megathermal climates, high temperatures are reached also with the optimal glass.•In dry and temperate/mesothermal climates, the best solutions work better in winter than in summer.•In continental/microthermal and polar climates, the best solutions strongly reduce the external cold. Solar greenhouses are currently the most energy-intensive agricultural sector. In literature, there is no worldwide mapping of solar greenhouse performance under different climate scenarios. This study analyzes the performance of a Venlo solar greenhouse for 48 localities around the world. Solar greenhouses are mainly made of a transparent envelope and the effect of the direct and diffuse component of solar radiation impacts the internal plant well-being. This study aims to identify the best solution of a transparent envelope on locations with different latitudes and evenly distributed around the globe. The simulations are carried out using TRNsys, considering different thermal phenomena three-dimensional shortwave and longwave radiative exchange, airflow exchanges, presence of lamps with their exact 3D position, ground, plant evapotranspiration, and convective heat transfer coefficients. A total of 336 simulations are performed in the free-floating regime. A new index for the identification of the best glass solutions based on annual average deviation is defined. For all climates, the best glass solutions work better in winter than in summer. The optimal choice of the glass must be combined with effective scheduling of openings for natural ventilation to avoid internal overheating phenomena.