Optimization of Greenhouse Thermal Screens for Maximized Energy Conservation

Rasheed Rasheed,Na Na,Kim Kim,Lee Lee

doi:10.3390/en12193592

Rasheed Rasheed, Na Na + Show 2 more

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https://doi.org/10.3390/en12193592

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Abstract

In this work, we proposed a Building Energy Simulation (BES) dynamic climatic model of greenhouses by utilizing Transient System Simulation (TRNSYS 18) software to study the effect of use of different thermal screen materials and control strategies of thermal screens on heat energy requirement of greenhouses. Thermal properties of the most common greenhouse thermal screens were measured and used in the BES model. Nash-Sutcliffe efficiency coefficients of 0.84 and 0.78 showed good agreement between the computed and experimental results, thus the proposed model appears to be appropriate for performing greenhouse thermal simulations. The proposed model was used to evaluate the effects of different thermal screens including; Polyester, Luxous, Tempa, and Multi-layers, as well as to evaluate control strategies of greenhouse thermal screens, subjected to Daegu city, (latitude 35.53 °N, longitude 128.36 °E) South Korea winter season weather conditions. Obtained results show that the heating requirement of greenhouses with multi-layer night thermal screens was 20%, 5.4%, and 13.5%, less than the Polyester, Luxous, and Tempa screens respectively. Thus, our experiments confirm that the use of multi-layered thermal screen can reduce greenhouse heat energy requirement. Furthermore, screen-control with outside solar radiation at an optimum setpoint of 60 W·m−2 significantly influences the greenhouse’s energy conservation capacity, as it exhibited 699.5 MJ · m−2, the least energy demand of all strategies tested. Moreover, the proposed model allows dynamic simulation of greenhouse systems and enables researchers and farmers to evaluate different screens and screen control strategies that suit their investment capabilities and local weather conditions.

Highlights

Different heating systems are typically used during winter to achieve the desired greenhouse micro-climate
In one of our previous studies [22] we presented a detailed literature review of TRNSYS software used for greenhouse modeling
The computed internal temperatures of greenhouses were compared with those experimentally obtained with temperature controlled natural ventilation, with night heating set point and with thermal curtain separately

Summary

Introduction

Different heating systems are typically used during winter to achieve the desired greenhouse micro-climate. Use of such systems leads to significant increase in greenhouse energy consumption [1]. Various technologies, renewable energy, are being utilized globally to fulfill energy requirements in buildings in general, including in the agriculture sector. Beside applying appropriate heating systems, energy saving measures requires careful consideration [2]. Energy saving is one of the most significant challenges, as heating costs have increased to more than 40%. Among the passive heating modes, use of thermal screens is the most influential means to reduce heating requirement. Improving energy performance of the buildings can Energies 2019, 12, 3592; doi:10.3390/en12193592 www.mdpi.com/journal/energies

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