Button Up For Energy Savings
by Michael Kovalycsik, National Sales & Marketing Director, Delta T Solutions
When the mercury drops and the winter winds start to howl, it’s time to assess the heating situation in your greenhouse operation. High energy costs and a growing responsibility to use energy more efficiently are leading growers to investigate current energy use and find more efficient methods. With significant research, both at universities and in private industry, many growers cannot afford to remain stagnant with existing, aging heating systems. Take the time to examine and seal up your greenhouses this winter to improve your bottom line.
STEPS TO TAKE NOW
If your operation is not in the position to replace its heating system this year or even in the next few years, there are a few things you can do now to seal up your greenhouse from the winter weather and improve your current system’s performance.
Timely maintenance of your existing equipment is the fastest and least expensive way to cut energy costs:
1. Identify problems by surveying the air temperature at crop height. This will be most easily observed in the early morning hours, when outside air temperature is lowest and the sun hasn’t begun to influence heating needs. If the temperature is consistent and at the desired level, this indicates your system is likely working correctly.
2. If the temperature is higher than necessary, reduce the thermostat accordingly. Keeping a greenhouse one degree warmer than needed can increase gas bills by up to 15 percent; however, keep in mind that changing the temperature may also slow down production time.
3. Calibrate your thermostat to ensure that the set point temperature and the air temperature are consistent. Any differences in these temperatures can be attributed to a calibration error or locating the thermostat in a colder location of the greenhouse. Label a tag with the calibration date and temperature correction factor and place it on your thermostat for future reference.
CHECK FOR AIR LEAKS
Air temperatures should be uniform from crop to roof; higher air temperatures near the roof indicate inadequate air movement in the greenhouse. Poor air circulation allows cold air to settle to the floor and warm air to rise to the roof. Air can be mixed with a horizontal fan or jet tube unit. Reducing air temperature near the roof by one degree may lower fuel use by 10 percent.
SMALL INVESTMENT, BIG SAVINGS
A few minor investments can help maximize energy efficiency. Adding a second or third layer of covering will increase the insulating effect of the greenhouse. For example, a polyethylene subroof installed under the roof tresses will reduce fuel use by 20 to 30 percent. All heating and ventilating systems must operate below the subroof and energy savings can recoup the investment in one or two seasons.
Thermal blankets extended inside the walls and roof at night can reduce energy use by 35 to 50 percent; insulated thermal blankets have even greater potential for savings. Rigid board insulation applied to the inside of north walls and below bench height on other walls reduces energy use by 5 to 10 percent.
Bench space typically occupies 65 percent of total greenhouse area. Installing moveable benches can allow increased access to plants while increasing useable bench space to about 85 percent of the greenhouse area and cutting energy use by 30 percent per plant sold.
COOL IT DOWN
Growing crops cooler could make a big difference in energy savings, too. For greenhouse operations in northern latitudes, energy costs for heating alone account for 10 to 30 percent of their total operating cost. According to research trials at the University of New Hampshire and Purdue University, some of the reported benefits of finishing poinsettia plants under cooler temperatures included reduced or no PGR use, an increased post-harvest life of plants and intense and brighter bract colors.
For more energy saving ideas, contact a Delta T Solutions representative by calling 800-552-5058; e-mail firstname.lastname@example.org.
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