Environmental factors are another benefit. Johnson noted that the University of Minnesota has successfully supported the progress in technology and developing the “next generation of high tunnels.” The farm currently utilizes solar high tunnels to prevent the soil from freezing. However, high tunnels do not protect against greens that have already grown above the soil. Unfortunately, it only takes one freeze to destroy these crops. Alternatively, an enclosed Deep Winter Greenhouse uses solar energy to heat the inside up to 100˚ F during the day. At night, the stored heat releases into the greenhouse and keeps the temperature between 45˚ F and 50˚ F. They are also more precise and efficient with water and energy compared to a typical greenhouse or the field.

Daniel Handeen, a researcher at the Center of Sustainable Building Research, shared that the most significant factor that the greenhouse is addressing is energy consumption. “We are trying to make as much use of the sun’s light and heat energy as we can, all while keeping the environmental control systems relatively low-tech, and the construction materials relatively low-impact,” said Handeen. The solar energy created within the greenhouse will allow farmers to have better control of the temperature there, leading to more control of the energy consumed.

Handeen explained that the solar panels are placed directly south at a 60˚ angle, capturing the maximum amount of sun on the coldest days of the year. There is a duct on the ceiling that will capture the hottest air that has risen. This air will then be sucked to the ends on the building, and finally drawn to the back of the greenhouse (north end) and into a 4-foot rock bed under the surface. Heat transfers through the rock, and comes up through the air ducts, preserving the stable temperatures within the greenhouse. For more information about the design, click here to access the complete blueprint of the Deep Winter Greenhouse or review the air circulation schematic.

Extending the growing season is beneficial to both farmers and consumers. “It has been a fun new adventure,” exclaimed Knisley. “Growing in the winter adds to the whole operation because as the season winds down, we would like to still be growing vegetables.” Handeen hopes to see “decentralized, high-quality, low-energy food production” within neighborhoods across the state all year long with the installation of more Deep Winter Greenhouses. Thank you to Alternative Roots Farm, Grampa G’s, and Daniel Handeen for your work researching this new innovation and producing fresh produce for Minnesotans.