Greenhouse Designed For Minnesota Winters

Greenhouse Designed For Minnesota Winters CROPS Miscellaneous A “Deep Winter” greenhouse designed at the University of Minnesota captures excess heat during the day and releases it at night The greenhouse has a 4-ft deep insulated bed of crushed rock beneath a steeply sloped south-facing greenhouse wall An insulated rear wall helps to hold heat The glazing is triple wall polycarbonate “The polycarbonate isn’t supposed to discolor over time or reduce light ” says Greg Schweser at the U of M’s College of Design Center “We know there are cheaper designs but we hope this is the most efficient and most durable and hold heat better and longer than conventional designs ” The warm air is pulled down into the rock bed where it disperses through perforated double-wall smooth interior drain tile When the inside air reaches 38° degrees a thermostat triggers a fan to pull heat out of the thermal bed via a second length of drain tile It pushes it out through an exhaust manifold into the greenhouse The prototype 18-ft wide by 24-ft long greenhouse has a material cost estimated at around $14 000 Labor roughly doubles the cost The greenhouse could back up against another building or even into a hillside However the design calls for a stand-alone building that can take full advantage of solar energy One market gardener built a version into a hillside with a root cellar behind it They then pulled an old resort cabin into place above the root cellar for living space A heated lighted greenhouse requires high value crops to recover costs says Schweser This design is intended for cold weather crops that will thrive in a greenhouse without supplemental lighting and with minimal supplemental heat Contact: FARM SHOW Followup Greg Schweser University of Minn 411 Borlaug Hall 1991 Upper Buford Circle St Paul Minn 55108 ph 612 625-9706; schwe233@umn edu; www extension umn edu/rsdp/statewide/deep-winter-greenhouse/

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