Monitoring of Climate Variables in Semi-Closed Greenhouses

Abstract

Growers and Dutch government have concluded a covenant in which they express the ambition to reduce the carbon footprint of greenhouse production in order to improve the energy neutrality of newly built greenhouses. Conditioned cultivation in (semi-)closed greenhouses is seen as one of the instruments to reach this goal. It is appointed in the covenant to arrive in 2011 at 700 ha and in 2020 at 2,500 ha semi-closed greenhouses. This paper describes the instruments used to monitor the results of conditioned cultivation in eight semi-closed greenhouses in practice. It addresses the monitoring process, the installations involved and highlights some of the measured data.

An overview of climate and crop yield in closed greenhouses

“…A uniform greenhouse climate is desirable in order to have temperature and humidity levels as close as possible to the optima for growth at any location in the greenhouse. In closed systems, where the air is distributed via ducts underneath the canopy, the horizontal and vertical distributions of air temperature and humidity in large greenhouses require special attention (Gieling et al, 2011). The cold air blown into the lower part of the greenhouse results in a stagnant vertical temperature gradient, which can be up to 5º -7ºC , with the lower temperatures at the bottom of the greenhouse.…”

“…Scaling-up from experimental closed greenhouses of approx. 100 m 2 , to nurseries of several hectares, air circulation-based heating systems gave rise to several problems (Gieling et al, 2011). In a relatively small experimental greenhouse, almost no horizontal differences in temperature were observed.…”

Model Simulation of Cucumber Yield and Microclimate Analysis in a Semi-closed Greenhouse in China

“…The energy systems of the semi-closed greenhouse include groundwater sources (hot-and cold-water wells), groundwater energy exchange system (high-efficiency plate energy exchanger), heat pump, the end system (greenhouse heating ducts and ATU), and energy storage system (heat storage tank and cold storage tank). The operation manners of energy systems and climate controls can be referenced in De Gelder et al 2012, Gieling et al (2011), and Kaukoranta et al (2014), which mainly depend on energysaving strategies and commercial crop management practices in China.…”

Crop growth and development in closed and semi-closed greenhouses

“…In our experiment, in which tomatoes were grown in semi-closed greenhouses with cooling ducts below the gutter, the plants experienced a VTG of > 5°C during the day in summer, which is in agreement with results in other (semi-)closed greenhouses (Hoes et al 2008) and in other high-wire grown crops such as cucumber and sweet pepper ). Gieling et al (2011) pointed out that a VTG requires special attention, since the response of a crop to such a microclimate was unknown. Our results show that the rate of truss initiation, production and partitioning of DM, and yield were not different in the treatments with or without a VTG, when the temperatures at the top of the canopy were the same.…”

“…Semi-closed greenhouse systems were also applied to ornamentals such as cut roses, orchids and other potted plants. The largest scale in which a closed greenhouse is applied in the Netherlands is 3.4 ha, combined with 5.9 ha open greenhouse (Gieling et al 2011). In total there are about 200 hectares of semi-closed greenhouses in the Netherlands (Kas Als Energiebron 2017).…”