The insulation value of a Chrysanthemum greenhouse has been increased by creating a cavity in the blackout screen and by using a transparent energy screen. The dry U value of the greenhouse decreased from 3.00 W/ m²/K for a conventional blackout screen to 1.67 W/m²/K (44% reduction) for a blackout screen with cavity and a transparent energy screen. The transparent energy screen provides the largest U-value reduction of 33% and the cavity in the blackout screen provides a U-value reduction of 17%. However, the substantial U-value reduction does not lead to an equally large energy saving because the higher insulation value of the screens only has an influence on the energy consumed to fulfil the heat demand when the screens are closed. In the better insulated department, the energy consumption through the heating pipes was 27.1 m³ gas/m²/year and in the reference department 30.4 m³ gas/m²/year. The energy savings due to the higher insulation value in the dark period of the greenhouse is 1.9 m3 gas/m2, which amounts to a total energy saving of 6.3%. Due to the energy savings the relatively low additional investment of making the cavity in the blackout screen can be earned back in a Chrysanthemum greenhouse with artificial lights. The investment in the transparent energy screen and associated screen installation cannot be fully earned back by energy saving alone. The application of multiple screen layers had no demonstrable effect on the quality and production of Chrysanthemums
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