Growers have a range of options to help contain, and even lower, production expenses when costs rise.
Lowering production costs and increasing efficiency is increasingly important as labor, energy and input costs from pots to pesticides are getting more expensive. Fuel and energy costs alone are up more than 30% over last year. While consumer spending has been strong on lawn, garden and greenhouse products, which has offset some of the expenses, growers can’t rely on that to continue.
“It’s too early to know if consumer spending will continue the way it has,” says Charlie Hall, professor and Ellison Chair in International Floriculture at Texas A&M University. “Gas is so expensive, but the data through April shows it had NO effect on the number of miles driven. People afford the things they want. But if higher airfare and fuel costs keep people at home more this summer, that may work in our favor, as it did during the pandemic.”
The good news is that there are tried-and true-strategies that will help minimize those costs, and in some cases, realize significant savings. Some of these are easy to execute, while some require some upfront capital. The return on investment of capital improvements can be realized rather quickly, however, making the effort worthwhile.
Below are five ways you can reduce your production costs:
Combining an environmental control system with staged venting allows growers to add to energy savings through passive ventilation.
1. Implement Energy-Saving Strategies. This may sound obvious, and no doubt you are taking measures already. But are you doing everything you can? You may have missed a few, so here’s some suggestions from Rutgers University Extension Specialist A. J. Both.1
- Lower thermostat set points at night. This will significantly reduce your heating costs because it will reduce the temperature difference between the outdoors and inside of the greenhouse.
- Add energy curtains. These thermal curtains are pulled across the greenhouse at night to reduce the volume of air needing to be heated, while also reducing heat lost through the roof. In addition, they can double as shade cloths and save on cooling costs. Growers have realized as much as 30-50% savings on their energy bill by using energy curtains.
- Insulate the perimeter of foundation walls and north walls to reduce heating loss.
- Double glaze with glass or poly to reduce as much as 50% heat loss as compared to single glazing.
2. Incorporate Under-Bench Heating. Multiple options are available for under-bench heating, but they all follow the same principle: Put the heat where the plant is.
“A unit heater hanging 5’ to 6’ above the crop is only about 82% efficient,” says Mike Kovalycsik, Regional Sales Manager at Stuppy Greenhouse. “Unit heaters blow warm air, which circulates around the greenhouse. Warm air rises, so some of that goes straight up — away from the plants — and it’s wasted. Under-bench heat is supplied by hot water from a boiler, and it is 90-95% efficient. There is far less wasted heat, and it’s going right to the root zone.”
Hydronic heating options such as under-bench fin heat can save growers 20-30% in heating costs.
Under-bench heating creates a more uniform root-zone temperature than a system that heats air. This results in better germination and rooting of young plants, and faster root and plant growth overall.
“If you’re boiling pasta on a stove, you don’t put the heat on top of it — you put it underneath the pot,” Kovalycsik says. “It just makes sense.”
Installing a hydronic heating system (meaning it uses water) requires a boiler, as well as the tubing system, and there are several configurations to fit the needs of your specific operation. Skirting of the benches with weed barrier fabric or plastic sheeting at an 18” length provides further heat conservation. Kovalycsik says a hydronic heating system can pay off quickly, saving 20%-30% in heating costs.
3. Preset Cooling Stages. Exhaust fans, while common, are not the most efficient way to cool a greenhouse, Kovalycsik says. They use electricity, which is expensive, and they are always on. He recommends using passive ventilation when possible and setting the environmental control system to activate cooling in stages. “First, you would open the roof vents, and then a bit wider, and then the sidewalls at different stages. Then, if needed, turn the exhaust fans on at a low speed and higher if necessary.”
Having these stages set up at proscribed temperature and humidity levels allows you to take advantage of the energy savings of passive ventilation while knowing your fans will kick in if needed, he says, continuing, “I’ve had growers call me up a year later and tell me how well this worked.”
4. Allow Your Equipment to Work. Algae-clogged cooling pads, plugged drip emitters and dust-covered thermostats cannot operate at their best. Follow these tips to keep your equipment running well:
Regular maintenance and algacidal, fungicidal and bacterial solutions will keep equipment like wet walls operating at their best.
- Position thermostat sensors correctly near the center of the crop for the most accurate reading of the temperature around the plants. Shield thermostats and sensors from direct sun, and make sure they are clear of dust and debris. For the most accurate reading, thermostats should be in an aspirated box that contains a small muffin fan that pulls the air through the box. Research at Rutgers University shows the high/low temperature spread in the greenhouse was reduced from 8°F to 2°F when the thermostat was in an aspirated box, resulting in significant energy savings.
- Use algacidal, fungicidal and bacterial solutions to clean cooling pads and clear drip and mist nozzles.
- Maintain the heating systems. Whether a boiler, unit heaters, or a hot air system, clean or change filters, heat exchangers, lubricate moving parts and calibrate for accuracy annually.
- Clean and adjust vent louvres and make sure they operate and seal correctly.
- Clean gutters, make sure polylock is sealed, check for holes in energy curtains, poly coverings and doors, and repair them.
5. Conserve Water. Of course, look for leaks in pipes, hoses and nozzles. But there is more you can do. Growers in California and some parts of western North America may already be well-versed in water conservation measures. As areas affected by drought keep increasing, it may be time to consider closed systems that treat, contain and reuse irrigation water.
“Customized systems combining ebb and flood irrigation systems, pumping systems and water treatment and containment not only increase the quality of your water, but also significantly reduce your water bill,” Kovalycsik says. “Water runoff and nutrient input costs are two more major reasons to make sure your water management system is operating efficiently.”
- A.J. 2008. “Ten Ways to Reduce the Greenhouse Energy Bill”. https://nj-vegetable-crops-online-resources.rutgers.edu/wp-content/uploads/2015/06/Greenhouse-Energy-Conservation.pdf