Oct 15, 2020
Image sourced from Ceres Greenhouse Solutions
Written by: Haley Bridgnell, Marketing at Ceres Greenhouse Solutions
Controlled Environment Agriculture is a method of food production that occurs in an enclosed, protected space like a hoophouse, greenhouse, or building. The aim of growing in this manner is to increase yields, extend the growing season, and/or make farming viable in more urbanized locations. CEA is becoming a popular growing solution due to the fact that it utilizes fewer resources (like land and water) and wastes less crop - qualifications that also make CEA a more sustainable alternative. But under the CEA umbrella, there are different types of facilities that operate under varying degrees of complexity - from fully sealed, closed loop systems to low-tech, plastic-covered high tunnels.
Greenhouses as CEA Solutions
While indoor farms are attractive because they can be placed in urban environments, they depend on highly-technical and often energy-intensive grow systems to operate. Greenhouses, on the other hand, rely on simple design principles, like building orientation, high light transmissive glazing material, and insulation to function at a basic level - before growing systems are added to increase productivity. All this is to say that if we are considering technology and design within the CEA industry that will advance sustainability, it’s important to acknowledge the simplicity and energy-efficiency of a greenhouse.
It’s indisputable that the most beneficial light for plant growth is from the sun. Sunlight has all the energy plants need to create food for themselves, and it provides intense light across the full-spectrum. Being able to harness this free form of energy is what distinguishes a greenhouse from other types of CEA operations. Without the sun, indoor growers rely on grow lights that are costly to install and operate. Commercial greenhouses do use supplemental lighting (in the wintertime or on a cloudy day), but they are intended to utilize mostly free and productive sunlight, which inherently makes them more sustainable.
Sustainable Greenhouse Design: Maximizing Solar Gain
It is important to note that some greenhouses are more energy-efficient than others. Key design features influence the amount of solar energy that can be harnessed in a greenhouse for increased light and heat.
Let’s start with the simple concept of greenhouse orientation. Depending on where the grow site is located geographically, a greenhouse should be oriented so that the roof glazing (the “see-through” material on a greenhouse that lets the sunlight in) allows for maximum solar collection. So, the ideal greenhouse orientation in the northern hemisphere would be east-west in order to maximize the area of south-facing glazing (because the path of the sun is south). Maximizing the amount of south-facing, highly light-transmissive glazing, will increase solar gain and ensure good light year-round.
With more light year-round, less supplemental lighting is needed during the winter months. Even with the sun low in the sky, an east-west oriented greenhouse will get plenty of winter sunlight. For growing operations in northern climates, less dependence on supplemental lighting can translate to significant utility cost savings.
In the northern hemisphere, the north side of the greenhouse is insulated, because it does not receive much light. Good greenhouse design aims to capture maximum solar energy, not only to aid in photosynthesis but also to keep the greenhouse warm. Insulating the walls of the greenhouse that aren’t needed for sun collection, like the north, east, and west walls, traps more light and heat in the greenhouse. Being able to harness more solar energy means less dependence on expensive and energy-intensive climate control systems.
Geothermal Heating and Cooling
Smart greenhouse design also uses the energy of the earth, in addition to solar energy, to heat and cool the growing environment. Geothermal heating and cooling is a CEA design feature that uses the steady temperature of the soil underground to regulate the internal temperature of a greenhouse. A geothermal HVAC system allows for renewable, year-round climate control at a fraction of the cost of a traditional HVAC system (like those used in commercial greenhouses or indoor grows).
These basic greenhouse design principles reduce overall environmental impact while still enabling a productive growing environment. By aligning to these principles and integrating smart growing systems, a greenhouse can yield just as much as an indoor grow facilities with less energy input - making it a more sustainable way of growing.
Learn more about passive solar greenhouse technology from Ceres Greenhouse Solutions at this year’s Agritecture Xchange. Ceres specializes in creating sustainable growing environments by combining smart design, innovative technology and dynamic partnerships.
Senior Solutions Architect, Josh Holleb, will be speaking on the ‘Advancing Sustainability in CEA through Technology and Design’ panel.
FURTHER READING:
VERTICAL FARMING GAINS MOMENTUM IN CHILE
PUBLIX IS HELPING PEOPLE CONNECT WITH THEIR FOOD THROUGH HYDROPONICS