Computing radiative heat transfers in greenhouses: a methodology coupling analytical and numerical approaches for view factors assessment

Soilless cultivation under heated greenhouses is a common practice for northwestern Europe tomato producers.
However, it comes with an important energy consumption that shall be more than ever addressed, especially because it still relies in a large proportion on fossil fuels.
Modelling the greenhouse climate and its effects on the crop growth and yield can help to evaluate existing and innovative heating systems in relation with the associated energy consumption.
Radiative heat transfers in particular shall be studied because of their magnitude compared with convection in greenhouses.
However, computing view factors, which characterize how surfaces “see” each other, is complex for greenhouse where the configuration does not correspond to simplified analytical cases, with obstacles and surfaces arrangement varying with time as the crop grows.
In this work, a methodology is presented to evaluate view factors in a 1000-m² soilless tomato experimental greenhouse fitted with three different heating pipe networks and air ducts below the gutters.
The approach uses free and open-source software in conjunction with analytical solutions whenever possible to reduce computation time.
The following elements are considered: floor, ducts, gutters, heating pipes, horizontal screens, roof and sidewalls.
View factors that depend on the crop growth can thus be formulated to consider the crop rows height and leaf area index (LAI), from low ones (where radiative energy losses with the roof and the walls might be important to assess for year-round energy consumption studies) to mature ones.
The methodology itself cannot only be applied to any other greenhouse arrangement, but also more generally to any geometry where radiative transfers occur within a volume that includes obstacles.

International Symposium on New Technologies for Sustainable Greenhouse Systems: GreenSys2023

S. Sourisseau, E. Chantoiseau, C. Toublanc, M. Havet

radiative heat transfer, view factor, energy efficiency, PyVista, PyViewFactor

https://doi.org/10.17660/ActaHortic.2025.1426.1