Energy saving greenhouse systems for sweet pepper production

Sweet pepper is an important crop for greenhouse production in the Netherlands. In three successive years trials are performed growing this crop in different greenhouse types with the goal a low energy input. The greenhouses are a double glass greenhouse, a double clad greenhouse with glass and foil and single glass-greenhouses with double and triple energy screens. The cultivars used were 'Maranello' and 'Allrounder'. The production in the trials (30-35 kg m^‑2) was comparable to commercial growers. In 2016 and 2017 no internal fruit rot was observed. The energy use was 355-535 MJ m^‑2, which is a reduction of about 50% compared to practical pepper growers in the Netherlands. Apart from using double covering materials, this reduction was realized by an intensified use of screens in the night and by a postponed stowing in the morning and the acceptance of higher humidity's compared to commercial growers. Postponed stowing results in a slight decrease in light availability but has an important effect on energy reduction and reduces the heating capacity needed. It is acknowledged that the reduced gas consumption for heating results in less flue gases for CO₂ dosing and therefore requires an alternative CO₂ source. The results show ready to use strategies for growers to reduce the input of energy and therefore provide benchmarks for the large steps that have to be made towards a fossil energy free greenhouse horticulture in the near future.