Retrofitting Options

Retrofitting Options

Retrofitting a greenhouse is all about spending money to save money. In many cases, increased energy efficiency may be the easiest way to see new technologies impact the bottom line. However, the benefit of improved crop performance should not be overlooked as a factor in the bottom line savings (or rather gains)–from faster turns and fewer chemicals to improved labor conditions and reduced disease potential.

Though there are numerous components of a greenhouse where retrofitting may result in greater efficiency, this article will focus on those that influence temperature and light.

Retrofitting Roll-Up Sidewalls

Patricia Dean also reported an increase in use of roll-up sidewalls as growers look to use natural ventilation as an energy saving tool.

Traditionally, roll-up sidewalls have been powered by a hand-crank or a tube motor. Neither of these methods is particularly appealing–the hand-crank obviously requires labor and special attention to the climate control, and the tube motors can wear out after a year’s use. The yearly replacement costs of tube motors (around $400 each) was unacceptable to some growers who began looking for a more durable option. Wadsworth’s VC 2000 ILS motor is a substantial piece of equipment costing around $1,100, but should last for at least 20 years.

The 360-foot roll-up system pictured here is using one VC 2000 motor.

Shade Netting

For years, shade netting was available in black with the amount of shade determined by how tightly knit the fabric was woven. The purpose was primarily to reduce heat or light. Over the years, new colors have been introduced, including an aluminum covered fiber, in an effort to manage the light while reducing the heat.

Frank Giglia, general manager of Signature Supply in Lakeland, Fla., explains, “Plants photosynthesize all day, but they only grow when the temperature range is between 60ºF and 100ºF.” In most parts of the United States, summer greenhouse temperatures can easily exceed 100ºF. Aluminet 50 percent, a specialty shade netting, can decrease the temperature by 20ºF, while only increasing the shade factor by 10 percent. Rather than blocking the sun’s light, the aluminum-coated weave disperses light over the plant canopy.

ChromatiNet is a line of colorful fabrics available in red, blue, gray and pearl. The red and blue fabrics specifically address the wavelengths of the light spectrum that affect plant growth and development. Red, for example, increases the diffused light spectrum to 600 nm and higher, maximizing photosynthesis and leading to faster overall growth. On the other hand, ChromatiNet Blue increases the light spectrum in the wavelength range from 425 to 490 nm, contributing to a reduced growth rate (eliminating the need for a chemical growth regulator) and delay of blooms.

The beauty of the colored shade nettings, besides their color, of course, is their ability to match your cultural needs. Giglia used two Florida growers as an example. Both grow New Guinea impatiens, but their growing environments are tweaked with different ChromatiNets to produce the best product for their customers. One grower uses blue to produce compact plants with lots of buds for landscapers. The other grower uses gray to get blooms as soon as possible so the plants can be shipped to Target.

In either case, a shade netting is a simple retrofit as an exterior covering. It is recommended as a year-round structural component in the southernmost states, and a seasonal addition in northern climates. The shade nettings last four to five years and cost around $0.21 per square foot. For more advanced light manipulation, the Aluminet and ChromatiNet coverings can be used in combination. 

Under ChromatiNet Blue, plants grow more compact with
darkerfoliage–desirable traits for foliage crops such as this
spathiphyllium. Blooming is delayed until plants are removed
from this ChromatiNet so blooming occurs at the
customer’s location.

Energy Curtains

Heat retention curtains have been the biggest category of increased sales in the past year for BFG Supply Co., Burton, Ohio, according to John Urbanowicz, technical service/product manager. Not only do the curtains provide 20 to 40 percent heat savings in the winter, they also provide cooling shade in the summer.

Urbanowicz says that for new builds, the curtain has become a standard feature. Retrofitting a house with a curtain may require some structural upgrades. Patricia Dean, vice president of customer relations at Wadsworth Controls, Arvada, Colo., agrees that the initial build is “the ideal time to install a curtain system.” Wadsworth also has seen a tremendous number of retrofits in the past several years.

The USDA offers a downloadable energy calculator, called Virtual Grower, on the Web ( Dean suggests growers use this tool to input their house dimensions, fuel consideration and temperature settings to assess their potential savings by installing an energy curtain. Simply run one calculation without checking the energy curtain box, then run a second calculation with the energy curtain box selected. The difference will help growers determine the potential benefit of a curtain system for their facility. Generally, Dean has found that the return on investment occurs in less than three years. Wadsworth promotes the rack and pinion system over the drum and cable system. Dean explains that the system will last seven to 10 years. With no cables to re-tension, the only maintenance (and therefore additional labor costs) associated with the curtain system is annual lubrication.

Dean warns that the labor to install the curtain system can cost as much as the curtain itself, though. Growers with construction experience may forego professional installation, but Dean and Urbanowicz suggest, at the very least, someone with installation experience should be hired to supervise and lead the project.

Urbanowicz cites 54 to 57 percent shade curtains as ones most commonly used by BFG customers. In addition to the typical shade fabrics, Dean also mentioned clear curtains, which allow for all day sunlight penetration while the curtain remains closed to retain heat in the winter. Another specialty curtain is made from open weave fabric that provides shade in the summer but lets heat escape through the curtain to the open roof vents. 

Energy Check-Up

Have you checked your thermostat lately? For every one degree of improved temperature accuracy, a three percent energy savings will be realized. It is not uncommon for a thermostat to be off by as much as five degrees. One easy way to help maintain temperature accuracy is to clean the aspirator filter/screen monthly.


Greenhouse glazings occasionally need to be replaced, and it’s a prime opportunity to investigate the latest innovations available. Polyethylene films are now available with anticondensate properties and increased thermal retention. Thermal films are more costly, but have the potential to reduce rising heating costs. Urbanowicz reports that a double layer of thermal film does not double the heat retention. Instead, many growers are choosing to use the thermal film as the exterior layer and an anticondensate film on the interior to maximize the benefits of both technologies.

As for acrylic glazings, DEGLAS recently introduced Highlux High Impact acrylic sheets that offer more optical clarity by having fewer interior sheet ribs. The ribs are spaced 96 mm (3 ¾ inches) apart, which equates to one third the number of ribs in 16 mm acrylic. Acrylic has long been valued for its high light transmission, but it also offers tremendous weather protection, particularly from hail damage, heat retention and an anti-condensate coating.

In addition to energy savings, shade nets, energy curtains and glazings contribute to improved crop quality, increased worker comfort, decreased water use and humidity and condensation control. In most cases, however, the fuel dollar will dictate the feasibility of retrofitting a greenhouse with energy saving technologies.

Leave a Reply

More From Greenhouses...

March 4, 2015

Nexus Corporation’s Cheryl Longtin Encourages Women To Seek Volunteer Leadership Opportunities

When Cheryl Longtin came to the horticulture business in 1994, she applied her experience in the automotive industry to promote the adoption of more technology in greenhouse production. Longtin says horticulture, with its rich family tradition, has long promoted women in the industry compared to other industries, but women in horticulture must continue to seek out opportunities to provide volunteer leadership in organizations that shape the future of the business.

Read More

March 4, 2015

Second Annual GreenhouseConnect Will Bring Growers and Suppliers Together in San Diego This October

Following a successful inaugural event in Tampa last fall, Greenhouse Grower has announced the dates of its second annual GreenhouseConnect: October 26-29, 2015. Representatives of an expected two dozen leading greenhouse operations from across the U.S. will join senior-level suppliers at Rancho Bernardo Inn in San Diego for several days of one-on-one strategic meetings, a growers-only roundtable, informational sessions and a variety of networking events.

Read More
cultivate'15 logo

March 4, 2015

Cultivate’15: AmericanHort Announces What’s New

In an industry that has seen major changes occurring at a fast pace, many industry professionals leave Cultivate with their heads spinning and no clear idea of how to regroup and strategize. Cultivate’15 is “Changing the Game.” As this year’s focus, Changing the Game will call your attention to the ways in which our industry has changed and your opportunities to compete successfully.

Read More
Latest Stories
Rough Brothers aeroponic greenhouse project

February 24, 2015

Rough Brothers Takes A Hands-On Approach To Several Pro…

Two projects Rough Brothers worked on for Altman plants in Giddings, Texas, and Scissortail Farms in Tulsa County, Okla., show that pre-planning on the grower's part opens the way for a smooth-running expansion project.

Read More
Stuppy Greenhouse Manufacturing's Rainbow Super Structure

February 23, 2015

Stuppy Greenhouse Manufacturing Says Every Customer’s G…

Well-suited greenhouses that function efficiently for customers arise from involving them in the design process from start to finish. Stuppy Greenhouse Manufacturing put this philosophy on a greenhouse design for a wholesale grower looking to expand his annuals operation. The grower's needs were simple, yet daunting: design a greenhouse that delivers the perfect growing environment, but keep maintenance and operating costs low.

Read More
National Greenhouse Manufacturers Association

January 27, 2015

Stricter Energy Codes May Impact Your Ability To Expand

Are you aware stricter energy codes may be on the horizon that will certainly impact your business in a big way? Here's a Q & A from the National Greenhouse Manufacturers Association that helps explain the dangers of the coming energy codes and what we as an industry can do to prevent them.

Read More

January 27, 2015

10 Questions To Ask Before Purchasing A Greenhouse Cove…

Whether you’re replacing an existing greenhouse covering or building a new greenhouse, it’s a significant investment, so you need to make sure you have the right type of covering to suit your needs and budget. What’s more, with production costs on the rise, you can’t afford to have anything less than a durable, high-quality covering that is energy efficient. To make a smart purchase, do your homework before you buy. A good place to start is by answering the following questions, which will help you separate the good products from the mediocre ones.

Read More

January 26, 2015

Greenhouse Growers Look To Build And Retrofit In 2015

You’re likely to see more construction work going on in the greenhouse industry in 2015, according to Greenhouse Grower’s 2015 State of the Industry survey. Responses show growers have high hopes for the future, which may be one reason why more of them are looking to spruce up their facilities.

Read More
Griffin Logo

November 10, 2014

Griffin Announces Dates For 2015 Grower And Retailer Ex…

Griffin Grower and Retailer Expo 2015 dates set for Massachusetts and Pennsylvania.

Read More

September 30, 2014

Emerald Coast Growers Adds Greenhouse Space To Increase…

Emerald Coast Growers has expanded with the addition of 25,344 square feet at their Milton, Fla., facility. The construction is in response to increased demand for their products, and will primarily be used for ornamental grass production.

Read More

June 6, 2014

High Tunnels: Reduce Heating Costs While Improving Bedd…

This is the first article in a two-part series featuring research from Purdue University that focuses on energy-efficient production of cold-tolerant bedding plants.

Read More

May 27, 2014

4 Ways To Finance Your Greenhouse Upgrade

If you’re ready to invest in greenhouse energy-efficient upgrades but aren’t sure how to finance them, there are a number of resources that can help.

Read More

May 22, 2014

Structures Issue: Growers Evolve With New Growth And Ma…

Is our industry really improving or does it just look that way? With growth in the past two years among Greenhouse Grower’s Top 100 Growers and the housing market on the upswing, the economy certainly is showing signs of life.

Read More

May 21, 2014

Lucas Greenhouses Gets A Jump On Spring Crops With Its …

A retractable roof greenhouse enables Lucas Greenhouses to start and finish part of its spring crop earlier and provides a superior production environment into the fall.

Read More

May 2, 2014

High Tunnels Help To Expand Markets, Crops

Growers are taking advantage of the USDA-Natural Resources Conservation Service’s Seasonal High Tunnel Initiative to extend the production season for a variety of crops.

Read More

April 24, 2014

9 High Tunnel And Shade Products For Your Operation

Extend the growing season and enhance plant quality with these nine high tunnel and shade products.

Read More
National Greenhouse Manufacturers Association

March 21, 2014

Greenhouse Heating Basics From The National Greenhouse …

Here's a Q&A from the National Greenhouse Manufacturers Association that might help you improve your greenhouse.

Read More
Greenhouse interior At Corsos

March 18, 2014

Will Greenhouses Add Production Space In 2014?

For those who are making changes this year, many responded that new production space will be used to extend their growing seasons, for early-season sales as well as edibles during the winter months.

Read More

February 25, 2014

Behind The New Greenhouse Projects At Van de Wetering A…

Read about the projects VB Greenhouses worked on at Van de Wetering Greenhouses and Kurtz Farms.

Read More

February 25, 2014

7 Spring Cleaning Tips For Commercial Greenhouses

During every busy shipping season you invariably run into issues that would have been eliminated had a little spring cleaning taken place. Here are a few points you may want to consider before spring shipping rolls around:

Read More

January 21, 2014

Exclusive: Danziger Is Building A State-Of-The-Art Stoc…

The breeder is constructing almost nine acres of state-of-the-art greenhouses near Barbarena, Guatemala, to bring its stock farm closer to the U.S. market. The first phase of construction was complete in February 2014.

Read More