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Possible steps towards sustainable, energy-efficient greenhouses
More intensive usage of screens - such as by closing screens for longer hours, especially during night time, and by using double screens - significantly improves insulation, and thus energy-saving. Some model calculations have shown that even adapting the criteria to close or open a normal screen can save up to 30 MJ/m2 energy per year. Adding a screen with a high insulating value can further decrease the energy demand by 115 MJ/m2 per year.
In general development and usage of screens that retain maximum PAR transparency, but are highly insulating and airtight, will retain energy in the greenhouse without compromising production. The desirable properties for screens are: high PAR transmission, low thermal transmittance (U-value) - which is a combination of low thermal conductivity, low air permeability, low emissivity and low thermal infrared transmissivity.