Although there is no universal definition for constructing "green" greenhouse structures, a good place to start is with environmentally and economically sustainable technologies.
May 6, 2011
In greenhouse construction, as in all other areas of the industry, there is no one-size-fits-all approach. Growers need to consider a number of factors, from location and climate to production and logistics, in the process of planning a new greenhouse.
But in the advent of the age of sustainability, growers are weighing another factor: green building. Is the process of building “green greenhouses” worth it in the grand scheme of things? Are there extra costs and what can be accomplished by sourcing green materials and environmentally friendly production choices? How can a grower get started down this path?
Greenhouse engineer A.J. Both of Rutgers University says, like the process of conventional greenhouse construction, in “green” construction, much depends on local conditions, crops grown, grower experiences and preferences, fuel cost and supply, greenhouse design and other variants. He adds that the individual grower’s definition of green building also plays a part in the process of building the greenest greenhouse, as well as where one might draw the boundaries – local, regional, national or global.
“The greenest greenhouse is planet Earth,” Both says. “Like other ‘green’ endeavors, the obvious benefits are to our environment and to our future, and there are no real drawbacks as long as the business maintains economic sustainability.”
With no current, standardized definition of a “green greenhouse,” its value is difficult to quantify and would depend on the operation, says Kurt Parbst of Ludvig Svensson.
“If there were a standard and a benefit, such as entry into a market or premium pricing, building green becomes part of the investment analysis,” Parbst says. “Each case would be different, so a good start would be to adopt current technologies that have been demonstrated to be efficient, arranged in a design that will make the operation profitable.”
Building From Scratch
New greenhouses should maximize energy conservation and recapture stormwater runoff, among other environmental objectives. Parbst says as part of this goal, new construction should be designed to deliver heat where it is needed to increase heating efficiency.
“Most plants grow closer to the floor than the ceiling,” he says. “Growing crops in cold weather is energy-intensive, so new greenhouses should have the economically viable level of insulation, which comes in the combination of glazing type and energy curtains.”
Rebates are available for growers using energy-efficient coverings such as double poly with an IR /AC layer or 8-millimeter polycarbonate, and some greenhouse manufacturers recycle construction materials.
“Green-Tek offers an exclusive polycarbonate buyback program, which reuses old polycarbonate, thus being very conscientious toward offering green programs,” says Erin Kelly of Green-Tek. “All Green-Tek plastic products are recycled.”
Many growers have opted to install biomass boilers, which burn renewable fuels. This is not only a greener option to burning fossil fuels, but it’s also cost-effective. Biomass energy is an unlimited and renewable energy source generated from the surplus of organic waste and agricultural waste generated every day. These fuels include:
• Wood cuttings, trimmings, wood chips, sawdust, etc.
• Paper/cardboard waste
• Agricultural waste (shells, husks, crop waste)
• Dedicated crops (corn, trees, grasses)
• Animal waste or other materials
Choosing hydronic, or hot water, heating systems over traditional forced air or space heater options is a green alternative that saves growers money without the additional investment of growing crops for fuel, as some growers with biomass boilers have taken on, according to Mike Kovalycsik of Delta T Solutions.
“Radiant heating systems offer accelerated germination, rooting and plant growth, as well as 20 to 30 percent fuel savings over conventional forced air heating,” he says. “Maximum soil and plant temperature control combine with the ability to create different temperature zones for growing flexibility.”
Consider cutting electricity use with the added potential of selling energy to the local power grid by installing wind turbines. Eagle Creek Growers was successful in obtaining alternative energy grants from the U.S. Department of Agriculture and the Ohio Department of Development to help pay for the turbine. The operation, based in Mantua, Ohio, is working toward installing another turbine and aspires to be fossil fuel free by the end of this year.
Capturing and reusing runoff can be accomplished relatively easily using recirculating irrigation systems, Both says.
“In addition, rainwater collection systems can be used to either supply additional water to the greenhouse system, or to replenish the underground aquifer, in case maintaining a certain groundwater table is important,” he says.
Growers can help prevent runoff and protect water quality by implementing the U.S. Environmental Protection Agency’s stormwater best management practices and learn more about the importance of protecting ground water.
Other important areas for environmental greenhouse design might include natural ventilation, coverings, curtains, flood floors and benches and drip irrigation.
LEEDing The Way
Growers can find guidance for green building through the U.S. Green Building Council’s (USGBC) LEED Rating System and Checklist for New Construction and Major Renovations, or on the USGBC website’s LEED Resource page.
LEED, which stands for Leadership in Energy and Environmental Design, is an internationally recognized green building certification system, providing third-party verification for buildings designed, constructed and operated for improved environmental and human health performance. LEED addresses all building types and emphasizes state-of-the-art strategies in five areas: 1) sustainable site development, 2) water savings, 3) energy efficiency, 4) materials and resources selection and 5) indoor environmental quality.
“I think most greenhouse operations would qualify for LEED silver recognition,” says Leigh Coulter of Growers Greenhouse Supplies (GGS). “Steel, aluminum, glass, poly, etc. are in many cases composed partially from recycled material. Steel uses scrap, glass uses broken glass, etc. Growers should look for help from greenhouse manufacturers and builders like GGS and JGS Limited that have LEED experience.”
The process of getting LEED certification for a green building is costly in that growers have to keep immaculate records of where materials are sourced and how they are used in the building’s construction, Coulter says. And while green building and LEED certification, by extension, are not currently mandated in the greenhouse industry, it’s likely the market will eventually demand more environmentally minded construction in the future.
“Today the benefits are mostly in personal satisfaction and marketing,” Coulter says. “In the future, the big box stores will be looking for growers who are LEED recognized to attract the consumer marketshare that values ‘green.’”
The USGBC also provides a number of reference books, including the LEED Reference Guide for Green Building Design and Construction, 2009 Edition, a user’s manual that guides a LEED project from registration to certification of the design and construction of new or substantially renovated commercial buildings. It is available for purchase on the USGBC website.