Greenhouse Horticulture in the Netherlands has set itself the task of having halved its primary energy consumption per unit of production at the end of the century, compared to 1980. As a result, a large number of energy-saving measures have been suggested to meet this target. In this book a simulation model is presented that can be used as a tool to judge the measures proposed. The model describes the dynamics of the greenhouse climate, the components of the heating system and the greenhouse climate controller with a time resolution of up to 1 minute. Also, the photosynthetic activity of the canopy is described. Consequently the model takes account for the complicated horticultural practice. The simulation model is constructed from sub-models. Each of these sub-models is discussed in detail. The sub-models for the heating circuit, the condenser and the short-term heat storage facility were newly developed. Therefore, these parts of the model are discussed extensively. The greenhouse climate controller and the greenhouse climate simulation are described integrally, however briefly, because these parts of the model are a reflection of the current state-of-the-art. To proof the quality of the simulation model, computations are compared to measurements on a rose crop in a research facility. These comparisons are made both with a high resolution on a small time scale (10 minutes) and with aggregated values on a large time scale (year round daily results). To analyze the prospects of energy-saving measures in greenhouse cultivation, the simulation model was applied to nine energy-saving options. The results of the model on these options with respect to energy consumption and biomass production are compared with a reference situation. The reference situation comprised a customary greenhouse growing tomatoes in the Netherlands. From the options evaluated, the application of combined heat and power and alternative cladding materials appeared to yield the largest decrement of specific energy consumption (the energy consumption corrected for production effects).

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Analyzing energy-saving options in greenhouse cultivation using a simulation model

http://digital.csic.es/bitstream/10261/3239/1/Revision_Day_and_Night_Wind____by_Playan_et_al.pdf

Day and night wind drift and evaporation losses in sprinkler solid-sets and moving laterals

https://irrecenvhort.ifas.ufl.edu/Teaching%20publications/Publications/COMPAG-2009-Greenhouse%20simulation.pdf

Dynamic modeling and simulation of greenhouse environments under several scenarios: A web-based application

A field experiment was performed to study the effect of the space and time variability of water application on maize (Zea mays) yield when irrigated by a solid set sprinkler system. A solid set sprinkler irrigation layout, typical of the new irrigation developments in the Ebro basin of Spain, was considered. Analyses were performed (1) to study the variability of the water application depth in each irrigation event and in the seasonal irrigation and (2) to relate the spatial variability in crop yield to the variability of the applied irrigation and to the soil physical properties. The results of this research showed that a significant part of the variability in the Christiansen coefficient of uniformity (CU), and wind drift and evaporation losses were explained by the wind speed alone. Seasonal irrigation uniformity (CU of 88%) was higher than the average uniformity of the individual irrigation events (CU of 80%). The uniformity of soil water recharge was lower than the irrigation uniformity, and the relationship between both variables was statistically significant. Results indicated that grain yield variability was partly dictated by the water deficit resulting from the non-uniformity of water distribution during the crop season. The spatial variability of irrigation water depth when the wind speed was higher than 2 m s−1 was correlated with the spatial variability of grain yield, indicating that a proper selection of the wind conditions is required in order to attain high yield in sprinkler-irrigated maize.

/pdf/wind-effects-on-solid-set-sprinkler-irrigation-depth-and-2n4noqqq40.pdf

Wind effects on solid set sprinkler irrigation depth and yield of maize ( Zea mays )

Greenhouses provide a suitable environment for the intensive production of various crops. They are designed to provide control as well as to maintain solar radiation, temperature, humidity and carbon dioxide levels in the aerial environment. CO2 enrichment decreases the oxygen inhibition of photosynthesis and increases the net photosynthesis in plants. This is the basis for increased growth rates caused by CO2 at low as well as at high light levels. Elevated CO2 concentrations also increase the optimal temperature for growth. The maximum crop response depends on the level of the balanced environmental parameters. Off seasonal cultivation is quite possible in greenhouse and it improves economic conditions of farmers. This paper reviews the available worldwide thermal modeling for heating, cooling and ventilation technologies and experimental studies of agricultural greenhouses.

Dvora Kantz

Papers

The distortion by wind of the distribution patterns of single sprinklers

Optimal CO2 enrichment strategy for greenhouses: a simulation study

In-situ determination of transfer coefficients for heat and water vapour in a small greenhouse

Transfer coefficients of several polyethylene greenhouse covers

Night-time use of dehumidifiers in greenhouses: an analysis