An efficient greenhouse design for hot climates

Ali, Hasimah; Moustafa, S.; El-Mansy, H.

doi:10.1016/0196-8904(90)90044-y

Cited by 11 publications

(4 citation statements)

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“…All shading methods are to regulate the amount of solar energy entering the greenhouse and reduce the heating load in summer. Besides protecting plants against excessive heat load, shading significantly reduces the water requirement in arid regions [ 34 ]. Disadvantage of shading system that used curtain or screen below the roof of the greenhouse is that when the curtain or screen is fully deployed, it will decrease the effectiveness of the natural roof ventilation and negatively affect the greenhouse microclimate.…”

Section: Greenhouse Cooling Challenges In Arid Regionsmentioning

confidence: 99%

Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Abdel-Ghany

Al-Helal

Al‐Zahrani

et al. 2012

The Scientific World Journal

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Cooling greenhouses is essential to provide a suitable environment for plant growth in arid regions characterized by brackish water resources. However, using conventional cooling methods are facing many challenges. Filtering out near infra-red radiation (NIR) at the greenhouse cover can significantly reduce the heating load and can solve the overheating problem of the greenhouse air. This paper is to review (i) the problems of using conventional cooling methods and (ii) the advantages of greenhouse covers that incorporate NIR reflectors. This survey focuses on how the cover type affects the transmittance of photosynthetically active radiation (PAR), the reflectance or absorptance of NIR and the greenhouse air temperature. NIR-reflecting plastic films seem to be the most suitable, low cost and simple cover for greenhouses under arid conditions. Therefore, this review discusses how various additives should be incorporated in plastic film to increase its mechanical properties, durability and ability to stand up to extremely harsh weather. Presently, NIR-reflecting covers are able to reduce greenhouse air temperature by no more than 5°C. This reduction is not enough in regions where the ambient temperature may exceed 45°C in summer. There is a need to develop improved NIR-reflecting plastic film covers.

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Section: Greenhouse Cooling Challenges In Arid Regionsmentioning

confidence: 99%

Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Abdel-Ghany

Al-Helal

Al‐Zahrani

et al. 2012

The Scientific World Journal

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“…Uneven span greenhouse yields a better thermal performance in hot and arid environments as the exposed roof area is less and the straight face of the roof will further shade the greenhouse. Long greenhouses develop undesired air and temperature profiles, and consequently additional evaporative cooling pads will be required for controlling the indoor climate (Ali et al 1990). This study found that a greenhouse with an aspect ratio of 1:3 will have a lower temperature distribution along 80% of its length.…”

Section: Recommendations For Optimizing the Greenhouse Structural And Operational Parametersmentioning

confidence: 99%

Experimental and numerical investigation of the thermal performance of evaporative cooled greenhouses in hot and arid climates

Ghаni

El-Bialy

Bakochristou

et al. 2019

Science and Technology for the Built Environment

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The controlled microclimate of greenhouses is vital for producing quality yield. This paper investigates the thermal performance of an evaporative cooled greenhouse operating in Qatar. Three design factors affecting the greenhouse thermal performance were assessed, namely the greenhouse geometry, operational parameters, and its geographical location. Geometrical parameters include induction fan elevation, roof shape, and aspect ratio. Operational parameters refer to the air flowrate. The greenhouse location dictates the incident solar intensity that was studied. Computational Fluid Dynamics (CFD) was used to model a typical ASHRAE compliant greenhouse. The simulation results were validated using measured data of a greenhouse inner air temperature, relative humidity, and the global incident solar radiation, showing good agreement. Simulation results showed that induction fans located at or below the crop height resulted in lowering the average temperature of the greenhouse. Doubling of the greenhouse ventilation rate from 20 ACH to 40 ACH further decreased the greenhouse air temperature. Temperature rise due to high incident solar radiation is reduced by increasing the ventilation rates. The uneven span greenhouse roof shape resulted in the lowest average inner temperature. For the same greenhouse floor area and volume, the effect of the aspect ratio showed negligible differences.

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“…Shade net application with different perforated mesh size and their evaluation with respect to local climate and region is necessary to get cooling benefits in summer. Ali et al [18] developed an efficient greenhouse design for hot climatic conditions of Kuwait. Entry of solar radiation was allowed only from the roof of the even span greenhouse of 250 m 2 floor area where tomatoes were grown.…”

Section: Shadingmentioning

confidence: 99%

Technology and Studies for Greenhouse Cooling

Li¹,

Wang²

2015

WJET

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Greenhouse technology is an efficient and viable option, especially for the sustainable crop production in the regions of adverse climatic conditions. High summer temperature is one of the worst effects on greenhouse crop production throughout the year. The main purpose of this paper is to present some technologies and studies for greenhouse cooling in summer. In the paper, some applicable and practical cooling technologies have been discussed. The choice of efficient cooling method depends on many aspects, such as local climate, agronomic condition, design and covering materials. To achieve desirable benefits, the combination of different cooling methods is necessarily used. Analysis of earlier studies revealed that a naturally ventilated greenhouse with larger ventilation areas (15% -30%), provided at the ridge and side covered with insect-proof nets of 20 -40 mesh size with covering material properties of NIR (near infrared radiation) reflection during the day and FIR (far infrared radiation) reflection during night was suitable for greenhouse production throughout year in some special regions. Evaporation cooling is the most effective cooling method for controlling the temperature and humidity inside a greenhouse. However, its suitability is restricted to the respective region and climate when the humidity level is high. The entry of un-wanted radiation or light can be controlled by the use of shading. Researches show that shade net application with different perforated mesh size and their evaluation with respect to local climate and region are necessary to get cooling benefits in summer.

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An efficient greenhouse design for hot climates

Cited by 11 publications

References 0 publications

Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Covering Materials Incorporating Radiation-Preventing Techniques to Meet Greenhouse Cooling Challenges in Arid Regions: A Review

Experimental and numerical investigation of the thermal performance of evaporative cooled greenhouses in hot and arid climates

Technology and Studies for Greenhouse Cooling

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