Effect of covering materials on energy consumption and greenhouse microclimate

Zhang, Y

doi:10.1016/0168-1923(96)02332-5

Cited by 47 publications

(18 citation statements)

References 15 publications

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“…While the experiments heaters were operating, the ventilators were closed and an Aluminet 50-I aluminized screen (Polysack Plastic Industries, Ltd., Nir Yitzhak, Israel; 50% to 54% shading) was in place in greenhouse 1. Among passive heating systems, movable thermal screens are one of the most practical and appropriate means for reducing heating requirements in greenhouses during nighttime in the winter months [8,15–17]. Thermal screens influence convection, radiation, and latent heat transfer [18,19].…”

Section: Methodsmentioning

confidence: 99%

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Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

López

Valera

Molina-Aiz

et al. 2012

Sensors

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Abstract:The present work has developed a methodology based on thermography and sonic anemometry for studying the microclimate in Mediterranean greenhouses equipped with air heaters and polyethylene distribution ducts to distribute the warm air. Sonic anemometry allows us to identify the airflow pattern generated by the heaters and to analyze the temperature distribution inside the greenhouse, while thermography provides accurate crop temperature data. Air distribution by means of perforated polyethylene ducts at ground level, widely used in Mediterranean-type greenhouses, can generate heterogeneous temperature distributions inside the greenhouse when the system is not correctly designed. The system analyzed in this work used a polyethylene duct with a row of hot air outlet holes (all of equal diameter) that expel warm air toward the ground to avoid plant damage. We have observed that this design (the most widely used in Almerí a's greenhouses) produces stagnation of hot air in the highest part of the structure, reducing the heating of the crop zone. Using 88 kW heating power (146.7 W•m −2 ) the temperature inside the greenhouse is maintained 7.2 to 11.2 °C above the outside temperature. The crop temperature (17.6 to 19.9 °C) was maintained above the minimum recommended value of 10 °C.

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Section: Methodsmentioning

confidence: 99%

“…Aluminized screens allow energy savings of between 15% [8] and 60% [20] and increases of 3 °C in canopy temperature [8]. The use of thermal screens during the night can reduce heat loss rates by 23–24% in plastic greenhouses [15] and the heating requirements by as much as 60 to 80% in a double-glazed greenhouse [16]. …”

Section: Methodsmentioning

confidence: 99%

Thermography and Sonic Anemometry to Analyze Air Heaters in Mediterranean Greenhouses

López

Valera

Molina-Aiz

et al. 2012

Sensors

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“…Zhang et al [12] experimentally measured heat transfer coefficients across several glazings in operating greenhouses during both summer and winter conditions and found heat transfer coefficients between 2.9 W/m 2 K (for the best two-layer polyethylene glazing with an antifog treatment) and 3.4 W/m 2 K. It was also observed that thermal screens reduced night heat losses by 23-24 %.…”

Section: Introductionmentioning

confidence: 92%

Reducing Canadian Greenhouse Energy Costs Using Highly Insulating Glazing

Lubitz

2015

Renewable Energy in the Service of Mankind Vol I

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This study explores the potential to significantly reduce heating costs in northern climates by adding additional layers and types of glazing to simulate greenhouse-like structures with highly insulating roofs that still allow appreciable light transmission. Representative typical meteorological year (TMY) data are used with a one-dimensional multilayer heat transfer model to explore the potential of insulated glazing panels for increasing solar gain. The model was validated against interior temperature and exterior weather data collected at a small unheated greenhouse in winter conditions. It was found that it is possible to reduce winter heating energy costs by using thicker-than-normal insulated glazing, although in practice, energy savings will be offset by added costs of the insulated glazing and additional measures would be needed to minimize summer heat gain. However, the potential for reducing winter heating energy costs suggests potential for highly insulating, semitransparent cladding.

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“…For these reasons and in order to improve environmental sustainability, it is appropriate to modernise and upgrade the greenhouse heating plants by using renewable energy for heat production and improving the facilities and the energy saving (Abdel-Ghany, Istigami, Goto, & Kozai, 2006;Arbel, Barak, & Shklyar, 2003;Cohen & Fuchs, 1999;Fabrizio, 2012;Vadiee & Martin, 2012;Zhang, Gauthier, De Halleux, Dansereau, & Gosselin, 1996). From a study by the Council of European Energy Regulators (CEER), it appears that the incentive policies for renewable sources in different EU countries have binding targets with regard to the reduction of emissions, but the manner in which these objectives are achieved is left largely to the discretion of each country, which can decide on renewable energy incentives and their level or whether to invest in measures that promote conservation or energy efficiency (CEER, 2013).…”

Section: Introductionmentioning

confidence: 99%