Last year’s Polar Vortex and this year’s major snow events illustrate how these larger scale weather occurrences have a major impact on reducing the payback period for greenhouse energy conservation projects. As outside temperatures drop below normal, energy consumption goes up, and heavy snow fall can force growers to heat an empty greenhouse or heat an active greenhouse at temperatures higher than would be needed in a normal year. With a more efficient greenhouse covering, these added costs can be reduced. When you take a good hard look at the numbers, it makes more sense than ever to invest in energy efficient greenhouse covering.
For example, let’s consider the impact of a Polar Vortex event on a grower in Kalamazoo, Michigan. According to Jeffrey Andresen, the State Climatologist for Michigan, “The normal mean temperature during the winter months (DJF – December, January, and February) in Kalamazoo is 26.7°F (based on 1981-2010 normals). During the severe winter of 2013/2014, the mean DJF temperature was 20.1°F or 6.6°F below for Kalamazoo.“ Dr. Andresen continued, “To find a nearby regional site with a normal DJF mean temperature of 20.1°F, you would have to go to the Upper and Northern Lower Peninsulas of Michigan. In the recent severe weather event Kalamazoo was more like the more northern weather stations like Munising, Manistique, Kalkaska, Gaylord or Lupton.”
Utilizing the USDA-ARS Virtual Grower software, a representative 100’ long x 25’ wide 4 year double polyethylene (R-value 1.7) covered greenhouse in Kalamazoo saw an increase in energy consumption of almost $1,300 compared with the same greenhouse under normal Kalamazoo winter temperatures. The same greenhouse covered with an energy conserving product like 5 MM Solexx™ (R-value 2.3) greenhouse covering only experienced energy increases in the same Polar Vortex weather conditions of a little more than $820. The $480 worth of energy savings in this example is also independent of loss of electrical power causing inability to inflate your greenhouse covering to achieve your covering options insulation value.
So how does all of this impact the payback period of a greenhouse energy conservation project like recovering a greenhouse with Solexx? Let’s look at the numbers. The additional energy costs reduce the payback period (solely based on energy savings) to recover the greenhouse with Solexx instead of double polyethylene film by almost a year (0.85 years). Originally the project would have had a payback period of 4 years and with just one Polar Vortex type season, the payback period dropped to 3.15 years.
Major Period of Snow
Growers are often forced to run heaters in an empty greenhouse or increase the heat in an occupied greenhouse to help melt the snow and fulfill the requirements imposed by some insurance carriers to help prevent a heavy snow load from collapsing a greenhouse. These increased energy costs are often the sole financial responsibility of the greenhouse grower. Another option often requested by insurance companies is that you are asked to “cut the plastic”, allowing the snow to fall into the structure. This practice saves the greenhouse, but prevents it from being an income-generating venture. Any plants still in the greenhouse would also be collateral damage. Despite the option chosen, unreimbursed grower costs are certain to increase, income potential could decrease, and additional time out of your busy day will be needed to work with your insurance adjuster. A grower’s choice of greenhouse covering can also impact their annual premium. Greenhouse growers should check with their insurance company to better understand their policy specifics.
If we go back to the previously used example, under normal Kalamazoo weather conditions according to Virtual Grower, it would cost $1,679 to heat the double polyethylene covered greenhouse for the month of January to melt the snow off the roof. This assumes you normally would not start to heat the greenhouse until February. If the greenhouse was covered by a greenhouse covering like Solexx that allowed the snow to quickly slide off and did not accumulate, and you were saved the additional energy expense, then the payback period for recovering with the Solexx would drop from 4 years under normal conditions to just 3.05 years under a major snow fall event. This almost one year reduction in the payback period under this circumstance can change an energy conservation project from being reasonable, to a “no brainer.”
Now with the “new normal” being abnormal weather events like the Polar Vortex or Major Snow Events, it is important for growers to consider these factors when they decide on a greenhouse energy conservation improvement project, like recovering with Solexx greenhouse coverings. Greenhouse energy conservation projects reduce grower’s risks. They can provide a level of insurance against future energy increases, potential damage from major reduced temperature weather events (Polar Vortex) and effects of large scale snow weather patterns (i.e. Boston 2015) that you cannot find coverage for in a traditional property insurance policy.