Modeling Greenhouse Efficiency Virtually

Modeling Greenhouse Efficiency Virtually

When you’re comparing structures and coverings, wouldn’t it be great to know which styles and materials will perform best for you before you make a change or start to build? USDA’s free Virtual Grower software program allows you to do that by analyzing the efficiencies of your current structures and constructing models for new ones–all from the comfort of your office.

The idea began in 2003, when plant physiologist Jonathan Frantz joined USDA’s Agriculture Research Service at the University of Toledo in Ohio. His background was in vegetable crops and he started asking local flower growers how they make decisions related to the greenhouse environment–light, temperature and air movement.

With energy efficiency becoming a top concern, Frantz and programmers Bryon Hand and Lee Buckingham set out to develop computer-generated models that would help growers make informed decisions that directly impact energy consumption. The model allows growers to compare styles of structures, the materials they are built from, fuel sources and crop times based on temperature settings and regional climate.

In many ways, this software was developed by growers for growers. “More than 90 percent of what you see in the program has come from grower input and suggestions,” Frantz says. “On the costs page, we have the metrics growers prefer, like cost per square foot and cost per month. They wanted maximum BTUs to help them size boilers appropriately. We’re also working with engineers who have experience doing audits. We execute the ideas given to us.”

In addition to working with the Toledo Area Flower and Vegetable Grower’s Association, Maumee Valley Growers and OFA, Frantz has been collaborating with fellow researchers and faculty members at Michigan State University (MSU), North Carolina State University and Purdue University.

In the “Energy-Efficient Annuals” series we published in Greenhouse Grower, March 2009-February 2010, MSU researchers used Virtual Grower to estimate the cost to heat a half-acre greenhouse to produce each crop for different finish dates at different locations in the United States. This data showed sometimes it is more cost effective and energy efficient to grow plants at warmer temperatures and finish sooner, depending on the regional climate.

“One of the biggest users of Virtual Grower is Erik Runkle at Michigan State,” Frantz says. “He has really done things I wouldn’t think of at all and has probably used the program more than I have. He really pushed what it can do and what to add. He and his students did most of the modeling for different species.”

How It Works

To get started, go to VirtualGrower.net, which is part of USDA’s Agricultural Research Service website, and download the program. When the program is opened, the design page is displayed.

On Virtual Grower’s design page, select your city and state from the drop-down menus. A historical database for weather at that location is loaded, providing typical values of temperature, light and wind speed over the course of 12 months. The weather database from National Renewable Energy Laboratory has information from 230 sites.

The next step is to start building your greenhouse by clicking the “Add New Greenhouse” button. You can then create a simple greenhouse by entering information into the main design page or click on “Advanced Design Options” to create a more detailed greenhouse. Here, you can change the greenhouse’s various dimensions, roof shape and materials.

“You can enter in the new material and test it, or test a new heater or curtain that is not already in the program,” Frantz says. “Once added, you can select the new item from the menu, run a heating schedule and see if the numbers go up or down.”

Virtual Grower can help describe the air exchange rate (leakage or infiltration) for a greenhouse. This allows users to see how small changes in the greenhouse can impact their overall costs. The heating efficiency section allows users to describe overall heat system efficiency based on simple user input. Users can see how changes in the management of a heating system (such as maintenance frequency) can impact overall costs.

The program also allows growers to design complex and realistic heating schedules by clicking on the “Heating Schedules” tab. You can select your greenhouse and click on “Add Schedule” and then customize the schedule to match what you are modeling. Clicking the “Costs” tab will allow you to estimate your fuel costs based on location, fuel, heating schedule and greenhouse design.

The “Plant Growth” section allows growers to grow plants in their virtual greenhouses and see how different heating schedules will impact a plant’s development. Plant size and the time it will take to flower are estimated using light, temperature and CO2 concentrations in the greenhouse.

“A grower can do what-if scenarios in a few minutes, instead of changing systems and then finding out over several weeks or even a whole growing cycle, did I save money or lose it?” Frantz says. “Some of the findings have surprised me, such as the difference between glass and corrugated polycarbonate. Polycarbonate is actually worse than glass for heat retention. And others are counterintuitive, that you can save money by heating up the greenhouses, as was found in some of Runkle’s studies.”

Frantz also has been testing tried-and-true industry standards and rules of thumb. “I tested the rule that for every one degree Fahrenheit you reduce the temperature, you save 3 percent on heat,” he says. “For certain areas, it’s right on. For others, it’s higher or lower. It depends on the structure, too.”

A Work In Progress

The current version or generation of Virtual Grower is 2.5, and 3.0 is on the way. “The next version will be substantially different in appearance and we’re changing computer languages so Mac users and others can use it,” Frantz says. “We’re also going to have more graphics, graphs, interactive maps and pictures of greenhouse buildings, so as you’re building, you can see how things change in real time. In the future, there will be more eye candy and it will be fun to use.”

A Spanish version debuted in February. “This was targeted for the migrant labor force,” Frantz says. “Often times, they are in the greenhouses more than the manager and might know the facility better or more accurately describe and put in realistic numbers. It’s also a training tool for how a greenhouse works versus spending a whole season making mistakes.”

Virtual Grower has been tested and will continue to be tested in a number of commercial greenhouse operations, large and small. One 2.5-acre greenhouse operation in Ohio used it to justify an upgrade to its heating system, increasing efficiency from 60 percent to 80 percent. The operation typically spent $34,000 on propane a year and Virtual Grower and an outside engineer independently estimated the savings to be about $8,000 a year.

Another owner of a half-acre greenhouse in Ohio looked at saving energy by installing inexpensive, temporary side curtains. Most of the facility had single-layered glass walls. Just adding a plastic sheet on the west glass wall to enhance insulation was projected to result in a savings of $300-$400 from $6,000 spent on natural gas.

Another Ohio grower was looking to replace 20 old gravity-vented unit heaters with high-efficiency power-vented models. Upgrading from 60 percent efficiency to 80 percent was projected to save $15,500 off a $60,000 heating bill.

One grower building a new 5-acre gutter-connected facility used the model to compare a biomass heating system with a conventional natural gas-fired system. The model predicted the cost of heating to be about $56,000 per year, compared to the actual operational cost of the biomass heating system over the last two years at $50,000 a year.

In each case study, independent estimates and actual costs were used to verify the Virtual Grower projections. The program proved to be a valuable tool for growers calculating returns on their investments in improvements. Frantz is looking for more grower input and feedback.

For more information about Virtual Grower, visit VirtualGrower.net or contact Jonathan Frantz, USDA Agricultural Research Service, Toledo, Ohio, 567-277-0247, [email protected]

Leave a Reply

More From Finance/Operations...

January 31, 2018

Online Education Empowers Employees to Succeed

See how UF/IFAS online certificate courses helped employees at Costa Farms get ahead with their jobs.

Read More
Money-feature

January 25, 2018

Why It’s Critical to Understand Your Real Costs of Plant Production

It’s time to stop guessing and start calculating when it comes to finding out what your real cost of production is, and pricing products accordingly.\

Read More
Tax-Money

January 23, 2018

Learn How the New Tax Law Will Affect Your Greenhouse Business

AmericanHort will co-host a free “Comprehending the New Tax Law: webinar on Wednesday, Jan. 31, with K-Coe Isom, a national tax consulting leader.

Read More
Latest Stories

January 31, 2018

Online Education Empowers Employees to Succeed

See how UF/IFAS online certificate courses helped employees at Costa Farms get ahead with their jobs.

Read More
Money-feature

January 25, 2018

Why It’s Critical to Understand Your Real Costs o…

It’s time to stop guessing and start calculating when it comes to finding out what your real cost of production is, and pricing products accordingly.\

Read More
Tax-Money

January 23, 2018

Learn How the New Tax Law Will Affect Your Greenhouse B…

AmericanHort will co-host a free “Comprehending the New Tax Law: webinar on Wednesday, Jan. 31, with K-Coe Isom, a national tax consulting leader.

Read More

January 15, 2018

Missouri Greenhouse Grower John Tomasovic Dies

The patriarch of Tomasovic Greenhouses & Nursery, Inc. in Des Peres, MO, was a legend in the plant industry, and widely involved in many associations.

Read More

January 15, 2018

Perennials Icon Louis Stacy Dies

The founder of the former Stacy's Greenhouses in York, SC, passed away on Wednesday, January 10, 2018.

Read More
Charlie Hall Feature Image

January 9, 2018

AmericanHort Launches New Video Series on Profit Margin…

This week, AmericanHort is kicking off a four-part video series that offers perspectives on managing profit margins from AmericanHort’s Chief Economist, Dr. Charlie Hall.

Read More
Tax-Money

January 9, 2018

What You Need to Know About the New Tax Bill

The United Fresh Produce Association, which represents the needs and interests of fruit and vegetable growers, recently updated its members on how the recent passage of the Tax Cuts and Jobs Act might affect their businesses. Many of the insights provided by United Fresh also apply to greenhouse growers and nurseries.

Read More
Doug Cole, Owner of D.S. Cole Growers

January 4, 2018

D.S. Cole Growers Blazes Its Own Path to Growth

Known for its commitment to sustainability and innovation, this grower is one of the pioneering trailblazers changing the way horticulture does business.

Read More

December 31, 2017

Ag Exemption for New Trucking Regulation Still Under Re…

The Federal Motor Carrier Safety Administration’s trucking electronic logging device mandate, which took effect on December 18, includes an Hours of Service exemption that may or may not apply to greenhouses and nurseries.

Read More
Tillandsia Air Plants (Plantiflor)

December 15, 2017

Bonsall Nursery Devastated By California Wildfire

Rainforest Flora lost its main greenhouses and outdoor growing property in the Lilac Fire in San Diego.

Read More

December 9, 2017

Southern California Wildfires Narrowly Miss Most Grower…

Here’s an update on horticulture businesses in the areas affected by the California wildfires.

Read More

December 5, 2017

Skagit Horticulture Builds New, Inclusive Business With…

By merging two large-scale producers, Skagit Gardens and Northwest Horticulture, the new company has realized its strengths through focused divisions that emphasize efficiency and success.

Read More

December 4, 2017

Raker-Roberta’s Young Plants Debuts as Roberta’s Finali…

On December 1, Eric Wallien of Roberta’s Inc. in Waldron, IN, officially purchased C. Raker & Sons in Litchfield, MI. The new identity of the company is now Raker-Roberta’s Young Plants, according to a Dec. 1 letter to Raker’s customers, suppliers, and business partners from Vice President Susie Raker-Zimmerman. “There have been minimal changes in management and we will be providing the same products and services on which we have built our reputation in the industry,” Raker-Zimmerman said in the letter, which also announced the name change and new logo. The sale of C. Raker & Sons was announced in September . A series of events affecting Raker’s financial situation caused the need for the operation to find an alternate solution. Roberta’s had been a customer of Raker’s since 2011, and the fourth generation, family owned grower-retailer was a fan of Raker’s commitment to quality. The agreement to purchase C. […]

Read More

October 10, 2017

Sharpen Your Skills in Cost Management and Profitabilit…

The University of Florida is offering a new online course on costing and profitability. The course will take growers through the process of how to accurately evaluate cost of production, labor efficiency, pricing, and equipment investment decisions.

Read More
Willoway Nurseries Team

October 1, 2017

How Willoway Nurseries Gets Its Staff Engaged in The Co…

Willoway Nurseries in Avon, OH, is creating a culture with people who think, act, and feel like owners. Learn how its team is taking the business to the next level.

Read More

September 21, 2017

Horticulture Is All About Connections

The beauty of our industry is that we are more than willing to reach out and help those around us. What connections can you make today to help your business, and what can you offer to help another grower?

Read More
Worker taking cuttings at Vivero Internacional.

September 11, 2017

Vivero Internacional Elevates Clean Cuttings to New Hei…

One of the last independent cutting operations, this fast-growing company raises the standard for delivering clean, high-quality unrooted cuttings.

Read More
Selecta Sponsor bed at Raker trial gardens

September 5, 2017

C. Raker & Sons Acquired By Roberta’s Unique Garden…

Ownership will change hands in December, and Raker will supply young plants for the 2018 season. Beyond that, leadership of the two operations say they are excited to move forward with a partnership that will continue to supply the industry, and gardeners, with top-quality plants.

Read More