A sweeping revolution in the electronics industry has made greenhouse environmental controls more affordable and functional than ever. Growers can expect a quick payback on their investment and peace of mind knowing their crops are safe from extreme temperatures. In this article, we focus on the more entry-level controls that are accessible to smaller and midsized growing operations. They also make sense for growers who have a number of freestanding greenhouses instead of expansive gutter-connected ranges.
Integrating Heating & Cooling
Bartlett Instrument Co. has been providing solutions for growers who have been using thermostats to control greenhouse heating and cooling. “With thermostats, there’s one sensor for one appliance – one for heating and one for cooling,” Dave Bartlett says. “The problem you run into is if the cooling sensor is in the sun and it gets hot, cold air blows and then the heating sensor becomes cold and turns the heat on.”
Bartlett Instrument’s newest controller, V Smart, has a 24-volt DC motor to rollup sidewalls. By sampling trends in temperature in the greenhouse, the controller predicts what’s going on outside and rolls sidewalls up or down accordingly. “We make the controller do what the grower would do if he was standing there,” Bartlett says.
The controls are affordable enough that a grower can pay for them with energy savings in one season. “Our controllers start at $450 and are under $800 with a relay box. This includes everything installed,” he adds.
With electronic technology becoming more accessible and affordable, Bartlett is looking at ways to bring more functionality to simple controllers. For instance, Bartlett supplies devices for ceramic kilns in school systems. Teachers receive a text when the firing is complete.
“We could present the same package for greenhouses,” he says. “Growers could receive alerts for low or high temperature alarms via text or eMail. The more expensive systems already do this, but we’re bringing it to the lower-end controllers. With cell phones, the day is here where people want the knowledge in their pocket. The next generation of growers will expect it.”
A newer entrant to the market, Link4 Corp. introduced environmental controls to the greenhouse market seven years ago. While owner Yen Pham has a background in developing high-tech electronics, his business partner is from the nursery industry. Today, hundreds of growers are using Link4’s iGrow controls in North America.
Modern tech tools and capabilities provide enhanced functionality. Growers can monitor and adjust controls remotely via the Internet, which can be accessed anywhere via computer or smartphone. “With any smart phone with a browser, you can control the greenhouse environment as if you were standing in front of the controls,” Pham says.
The ability to upload and download information to each control unit via USB drive is another benefit, he adds. “You can place the controls in multiple houses and network them together or not. You can walk out to the greenhouses with a USB drive to download information, which is convenient. Programming 23 boxes by hand would be a pain.”
Growers also have the ability to track energy usage. “The user can put in how much he is paying for electricity, water, propane or natural gas and different rates for different times of the day,” Pham says. “It will tell how much you are spending and help you attack energy and water issues. People just don’t know what’s going on – how much energy they’re burning in that greenhouse because they don’t have the information.”
Price is usually the barrier to growers investing in this level of technology. “But our list price of $595 is very affordable, a foot in the door to start controlling your greenhouse,” Pham says. “You can even program the unit to tell you when it pays for itself in real time. In this economy, nobody wants to spend money on anything, but if you do the math and it pays for itself, you should make the investment in your operation.”
While most growers are primarily concerned with costs of heating and cooling greenhouses, in some parts of the country, water use is going to become increasingly important. “We’re putting a lot of development toward that,” he says. “Indoor and outdoor growers do use water, recycle and inject nutrients. They need the ability to water on demand as needed in a cost-effective manner. Somebody has got to tackle this.”
Learning Step By Step
Step Up Controls from Wadsworth Controls is a hybrid between integrated and staged controllers. While staged controls take all the equipment in the greenhouse and divide them into groups, integrated controls have on and off parameters for each piece of equipment. Wadsworth’s Step Saver is integrated and Step Up is staged.
Step Up Supervisor software allows growers to see all the controllers in a unified view with remote capabilities via computer or handheld devices and receive alerts. The program converts data to tables and graphs that are good analytical tools for energy use.
“Our Step Up Controls have been a good seller. We have customers with 16 Step Ups at their facilities,” says Patricia Dean of Wadsworth Controls. “Step Up has two heat stages and four cooling stages, which determine what gets turned on, whether it’s a pad, pump or energy curtains. These are triggered by temperature and humidity, not sunlight or soil moisture. The controls are simple and easy to understand. Ours also is the first staged control that allows growers to use DIF (manipulate the difference between day and night temperatures).”
The controls also can use variable frequency drives to control fans to save energy. Fans can come on in a sequence instead of all at once.
Wadsworth also has a virtual visit training program that helps clients get the most out of their controls. “We call customers to find out what they are doing, if they are using the features,” Dean says. “End users can become overwhelmed with manufacturer’s training in the beginning, so a year later we get in touch with a refresher training course via the Internet. Growers can record the session and watch it later. We are online at the same time, share the screen and can quiz them to make sure they’re learning.”