What are the differences and advantages of freestanding and gutter-connected greenhouses?
Greenhouses are buildings constructed from metal frames and covered with a translucent plastic film that provides full enclosure and can be equipped with vents, shades, irrigation systems, and lighting. Greenhouses can deliver highly controlled optimal growing conditions for plants and protect them from environmental hazards or inhospitable conditions outside. Greenhouses come in all shapes and sizes, from hobby greenhouses to commercial greenhouses and other configurations like cold frame greenhouses.
Greenhouses are a solution to the many challenges facing conventional outdoor agriculture. The success of crops is difficult to predict in the face of the limited amounts of land that can support crops. Unpredictable weather resulting from climate change, and the growing need for agricultural products also present risks to outdoor cultivation. Some plants are difficult to grow or require a highly controlled environment to ensure quality for medical products. Greenhouses offer a variety of designs and features that can meet those needs.
Planning Greenhouse Construction
Greenhouses come in a variety of shapes and sizes. Greenhouse shape and orientation are important features that influence crop success and operational efficiency. Less heating is required for east-west facing greenhouses than for north-south facing ones and latitude has an effect on how much energy reduction is realized. Light exposure and distribution can also be influenced by latitude and orientation so it is important to research a greenhouse site thoroughly.
General Considerations When Constructing a Greenhouse
Crops to be grown, growing season, production yield, growing systems and medium, and irrigation systems should be considered.
Land should have soil that drains well and at least two acres is ideal.
A location with a 1-2% slope to the south is ideal for sun exposure, drainage/runoff, and site preparation. A line of trees or shrubs called a shelterbelt located to the north of the site helps conserve energy and protect from wind.
Zoning requirements and building codes should be carefully consulted along with state and federal regulations.
At least 0.3 gallons of water is needed per day of growing season per square foot. The water supply will need to be tested to ensure it is of good quality and to select appropriate filtration systems if needed.
A site survey of the land should be conducted and a facilities master plan should be made to ensure that greenhouse construction meets the needs of the business plan.
Freestanding Greenhouses
Freestanding greenhouses generally have a quonset, gothic, or gable roof shape. Quonset style greenhouses are usually the least expensive but also offer the least amount of space. Gable styles are able to offer the most space, and gothic style greenhouses are ideal for withstanding snow and allow the most light transmission.
Advantages of Freestanding Greenhouses
Ideal for smaller growers that need less than 10,000 square feet of space.
Additional separate greenhouses can be built and can maintain different growing environments.
Individual structures can be shut down when they are not in use and are better for unlevel building sites and snowy regions.
Freestanding gothic or quonset greenhouses can be built 12 to 34 feet wide. Freestanding gabled greenhouses can be built up to 60 feet wide. Wider greenhouses allow for the most efficient use of space.
Gothic or quonset structural hoops are generally spaced 4-5 feet apart. Framed for gabled greenhouses are usually 8 or 10 feet apart. Greenhouses can be built to almost any length, but it may be economical to consider that polyethylene film for glazing comes in standard lengths of 48 ft, 96 ft, and 144 ft. Length is less of a concern if polycarbonate or acrylic rigid glazings are to be used.
Gutter-Connected Greenhouses
Bays that are 12 feet to 36 feet wide connect a series of gable or quonset style greenhouses to form gutter-connected greenhouses. If a space larger than 10,000 square feet is needed, gutter-connected greenhouses are the most efficient and economical option. If a gutter-connected greenhouse is greater than 200 feet long can present challenges for cooling and ventilation.
Advantages of Gutter-Connected Greenhouses
Heating can be centralized in gutter-connected greenhouses and reduce heating costs up to 25%
Natural ventilation and open roof designs reduce the costs of cooling; the temperature remains more stable so fans are not needed
Provided a gutter height of at least 12 feet in height allows for a buffering space filled with air and space which can be utilized for energy saving trusses and shade screens
Plenty of space for expanding future operations is provided
Centralized utilities are cheaper to install and maintain
More growing space can be provided using less land with gutter connected greenhouses