Unhappy plants, discontented workers and high production costs are all signs that it might be time for some changes to your greenhouses, says A.J. Both, associate extension specialist in the Department of Environmental Sciences at Rutgers University.
“Any or all of these conditions can be a good reason to investigate and implement upgrades,” he says.
Energy is one of the costliest aspects of running a growing operation, second only to labor expenses. According to a fact sheet produced by Both and Michigan State University’s Erik Runkle, approximately 65 to 85 percent of the energy consumed in greenhouse production goes toward heating, while electricity and transportation make up the remainder.
In older greenhouses, it’s common for air leaks to reduce efficiency, leading to higher energy costs. Both and Runkle recommend inspecting your current house’s glazing, walls, doors, fans and vents for leaks. Pay close attention to the areas around vents and fans, and spots where the covering attaches to the foundation and walls. They offer this checklist to help improve efficiency if you’re not quite ready for a complete retrofit:
- Patch holes in the plastic covering and side walls, or replace cracked or missing glass panes.
- Keep doors closed, and make sure they close completely.
- Weather-strip doors, vents and fan openings.
- Ensure louvers are sufficiently lubricated so they close tightly.
- Shut off some of your exhaust fans from late fall through early spring, then cover openings with insulation or plastic to reduce air infiltration.
- The unit is not properly maintained or adjusted.
- Deposits have formed on components of the combustion chamber.
- A heat exchanger is dirty.
- A fan distributing hot air or a pump distributing hot water is not working properly.
- The combustion process is not receiving enough oxygen.
While Both typically recommends building new structures with updated equipment if at all possible to ensure maximum efficiency, it might not be economically feasible for some growers. In those instances, he suggests considering the following upgrades for existing greenhouses:
- Take energy conservation measures (increased insulation, equipment maintenance, careful review of the control system and changes to crop scheduling).
- Install an energy curtain, preferably one operated with a computer control system.
- Install a new heating system that offers more efficiency.
- Investigate alternative fuels for heating your greenhouses.
- Install new glazing to increase light transmission, remove unintended cracks and small openings and improve insulating properties.