Certain Savings with Curtains
Energy curtains are one of the most cost effective options for growers looking to save on energy. In colder climates, 75% of your heating bill during the winter comes at night when solar gain in null and void. The best way to think about energy curtains is to consider them an extra layer of protection for your harvest that will help optimize the conditions within your greenhouse.
There are several realistic options to consider outside of energy curtains that will help reduce your energy costs; including venting systems, installing an environmental controller, using IR-polyethylene film, and installing a heating system. These are all viable options, and when bundled together with energy curtains, will create savings that will provide returns year after year.
Making the Case for Energy Curtains
According to a study by Michigan State University, installing energy curtains can save growers over a quarter of their annual energy bills. And these savings don’t take decades. Often, this investment will pay for itself within as little as two growing seasons.
A report from the National Greenhouse Manufacturers Association echoed this fact and found that “growers who have installed curtain systems commonly report annual savings of 30% or more.” In a market of ever-fluctuating energy costs, those savings add up quickly. And those savings can then be redistributed into your operation to expand and scale -- if that is something you've been considering.
We’d be remiss not to mention that the benefits of curtains go beyond cost considerations. They also benefit the environment in a big way; they do this by limiting the amount of water your shaded plants require in the summer or natural resources you need to heat your greenhouse in the winter.
The Difference Between Summer and Winter Usage
So we've established that energy curtains prevent heat loss in the winter and heat stress for crops in the summer.
Lets get a bit more specific with seasonal uses:
Winter use: In the cold depths of winter or on uncharacteristically cold evenings throughout the season, energy curtains are designed to retain heat. If you have a heater installed then curtains will also reduce your fuel usage and help regulate temperatures on the crop level.
Summer use: This option keeps the summer temperatures down in your greenhouse by diffusing the light coming through the roof. As an example, if you have a young crop of hydroponic plants sensitive to high intensity light, a light meter can be installed. If the meter is integrated with an environmental control system, the system can automatically close or open the curtains to assure temperatures are always at optimal levels.
There are several variables to consider when installing energy curtains for your greenhouse. There will be benefits specific to each operation and these considerations include; location, greenhouse size and shape, glazing material, crop heating set point temperatures, heating system efficiency, and fuel price in your area.
If you are not exactly sure of your energy costs and usage, the USDA’s Virtual Grower is a great place to start. This free tool will actually allow you to calculate your return on investment if you decide to install energy curtains, and help you weigh the pros and cons.
Take this example from Wadsworth Control Systems that used this tool. A greenhouse located in Concord, New Hampshire has two bays, is gutter connected, measures 96 ft. x 60 ft., and has a double poly covering. The greenhouse is in operation from September 1st to June 1st.
Annual heating costs of the greenhouse were $22,820. After installing an energy curtain, the annual savings reported were $8,870. Further, after adding an environmental control system that kept the night set temperature at 60 degrees Fahrenheit, the savings amounted to $10,366.
Those are staggering numbers and this is just one example of growers that have benefited from using energy curtains. If you have been considering ways to cut down on costs, retrofitting your greenhouse with curtains might just be your best option. To learn more, head over to our Learning Center and see what energy curtains can do for you!