Energy saving: From engineering to crop management

In greenhouse horticulture, energy costs form an increasingly larger part of the total production costs. Energy is primarily used for temperature control, reduction of air humidity, increase of light intensity and CO2 supply. Use of fossil energy can be reduced by limiting the energy demand of the system and decreasing energy losses, by intelligent climate control, by increasing the energy efficiency of the crop and by replacing fossil energy sources by sustainable ones. Energy requirement of the greenhouse can be lowered up to 20-30% by using greenhouse covers with higher insulating values and the use of energy screens. A prerequisite is that these materials should not involve considerable light loss, since this would result in a loss of production. In energy efficient greenhouse concepts, durable energy sources should be included. In (semi-)closed greenhouses, the excess of solar energy in summer is collected and stored in aquifers to be reused in winter to heat the greenhouse. Ventilation windows are closed, with specific benefits to the crop: high CO2 levels can be maintained, and temperature and humidity can be controlled to the needs of the crop. Development of new greenhouse concepts is ongoing. Current examples are greenhouse systems which convert natural energy sources such as solar energy into high-value energy such as electricity. Given a certain technical infrastructure of the greenhouse, energy consumption can be further reduced by energy efficient climate control and crop management. Essential elements are to allow fluctuating temperatures, lower crop transpiration, allow higher humidities, make efficient use of light and create fluent transitions in set points. Consequences for plant growth are related to rate of development, photosynthesis, assimilate distribution, transpiration and the occurrence of diseases or disorders. Since processes involved are complex, knowledge exchange between researchers and growers is essential to realize the goals set to reduce the energy consumption

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The effect of the sun and its path on thermal comfort and energy consumption in residential buildings in tropical climates constitutes serious concern for designers, building owners and users. Passive design approaches based on the sun and its path have been identified as a means of reducing energy consumption, as well as enhancing thermal comfort in buildings worldwide. Hence, a thorough understanding regarding the sun path is key to achieving this. This is necessary due to energy need, poor energy supply and distribution, energy poverty and over-dependence on electric generators for power supply in Nigeria. These challenges call for a change in the approach to energy related issues, especially in terms of buildings. The aim of this study is to explore the influence of building orientation, glazing and the use of shading devices on residential buildings in Nigeria. This is intended to provide data that will guide designers in the design of energy efficient residential buildings. The paper used EnergyPlus software to analyze a typical semi-detached residential building in Lokoja, Nigeria, using hourly weather data for a period of 10 years. Building performance was studied as well as possible improvement regarding different orientations, glazing types and shading devices. The simulation results showed reductions in energy consumption in response to changes in building orientation, types of glazing and the use of shading devices. The results indicate a 29.45% reduction in solar gains and 1.90% in annual operative temperature using natural ventilation only. This shows a huge potential to reduce energy consumption and improve people’s wellbeing using proper building orientation, glazing and appropriate shading devices on building envelope. The study concludes that for a significant reduction in total energy consumption by residential buildings, design should focus on multiple design options rather than concentrating on one or few building elements. Moreover, the investigation confirms that energy performance modelling can be used by building designers to take advantage of the sun and to evaluate various design options

CONSIDERATIONS CONCERNING THE AUTOMATION OF PROTECTED SPACES

In the last period there is an intensification of the researches oriented towards the automation of the specific activities of the horticultural production in protected spaces. The greenhouses offer a shelter in which a microclimate suitable for plants is maintained, which is obtained by regulating / adjusting the heat and the amount of light coming from the sun, by means of actuation systems (actuators-technical devices that generate an action to reach a specific objective). The paper presents a brief communication on the main drive systems used in greenhouses: ventilation and cooling systems; heating systems; irrigation systems, whose drive systems are mainly composed of electrical devices, especially electric motors or pump

Optimal greenhouse cultivation control: survey and perspectives

Abstract: A survey is presented of the literature on greenhouse climate control, positioning the various solutions and paradigms in the framework of optimal control. A separation of timescales allows the separation of the economic optimal control problem of greenhouse cultivation into an off-line problem at the tactical level, and an on-line problem at the operational level. This paradigm is used to classify the literature into three categories: focus on operational control, focus on the tactical level, and truly integrated control. Integrated optimal control warrants the best economical result, and provides a systematic way to design control systems for the innovative greenhouses of the future. Research issues and perspectives are listed as well

Comparative analysis of the management of the results of the modeling and the simulation of the evaluation of the thermal energy of the greenhouse by a fuzzy logic controller between a wet region and an arid region

Currently the climate computer offers many benefits and solves problems related to the regulation, monitoring and controls. Greenhouse growers remain vigilant and attentive, facing this technological development. They ensure competitiveness and optimize their investments / production cost which continues to grow. The application of artificial intelligence in the industry known for considerable growth, which is not the case in the field of agricultural greenhouses, where enforcement remains timid. It is from this fact, we undertake research work in this area and conduct a simulation based on meteorological data through MATLAB Simulink to finally analyze the thermal behavior greenhouse microclimate energy. In this paper we present comparison of modeling and simulation management of the greenhouse microclimate by fuzzy logic between a wetland (Dar El Beida Algeria) and the other arid (Biskra Algeria).Actualmente la computadora climática ofrece muchos beneficios y resuelve problemas relacionados con la regulación, monitoreo y controles. Los productores de invernadero permanecen vigilantes y atentos frente a este desarrollo tecnológico. Aseguran la competitividad y optimizan sus inversiones / coste de producción que sigue creciendo. La aplicación de la inteligencia artificial en la industria destaca por un crecimiento considerable, que no es el caso en el campo de los invernaderos agrícolas, donde la aplicación sigue siendo tímida. Es a partir de este hecho, que emprendemos un trabajo de investigación en esta área y realizamos una simulación basada en datos meteorológicos a través de MATLAB Simulink para finalmente analizar el comportamiento térmico de la energía del microclima de efecto invernadero. En este trabajo presentamos una comparación de la gestión de modelado y simulación del microclima de invernadero por lógica difusa entre un humedal (Dar El Beida Argelia) y otro árido (Biskra Argelia)