Designing energy efficient greenhouses incorporating renewable energy systems for year-round food security in North American winter climates
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University of Lethbridge. Faculty of Arts and Science
Lethbridge, Alta. : University of Lethbridge, Dept. of Geography
Local food production may not meet food market needs because of population growth and urbanization. Greenhouse cultivation has been used as an effective technique for providing an environment isolated from outside conditions to grow a wide variety of high-quality products with secure and sustainable harvesting in all seasons, especially in northern climates. The main problem with greenhouse cultivation is energy consumption required to maintain the indoor environment desirable for plant growth. Energy efficiency and conservation have become important issues around the world due to the cost increase, disruptions in availability, and the growing significance of environmental problems. Developing efficient greenhouses can be one of the most important actions to support food security and climate resilience. One objective of designing an energy-efficient greenhouse is to reduce CO2 emissions caused by burning fossil fuels to operate a greenhouse or generate electricity to be used in greenhouses so, increasing the investment in renewable energy for greenhouses is an energy-saving action. Therefore, the main goal of this study was to investigate energy-efficient designs of greenhouses for year-round food security in the harsh and changing climate of Southern Alberta, Canada. Using EnergyPlus™, a well-known building energy simulation tool, the most energy efficient greenhouse has been determined through modelling, simulation, and comparison of greenhouses different in parameters such as shape, dimension, orientation and covering material. In the first part of the study, the optimum design between 6 types of conventional greenhouses was investigated considering different variables for mentioned parameters. In the second part, the thermal performance and energy consumption of Conventional Greenhouses (CGs), Chinese Style Greenhouses (CSGs) and Plant Factories (PF) were compared and the most energy-efficient one was selected. After finding the greenhouse with the minimum energy requirement in the first two parts, the hybrid renewable energy systems have been selected for the optimized greenhouse structure using Hybrid Optimization of Multiple Electric Renewables (HOMER), to minimize the use of fossil fuels and reduce CO2 emissions. Economic criteria were considered as a substantial part of optimizing greenhouse design and hybrid energy system components. The results of the study showed the most energy-efficient design is a Chinese Style Greenhouse when it is built using affordable and thermal resistance materials. Using PV panels in a checkerboard layout along with a wind turbine on the roof of the greenhouse combined with the grid, was the most optimal on-grid power system.
energy efficient greenhouse design , renewable energy systems , year-round food security solutions , winter climates , northern climates , food security