RBR News | April 27, 2017

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Last summer, we designed and constructed a new passive solar seed “start” house to improve seedling preparation for the growing season. Several of the structure’s energy efficient features were made possible with a generous grant from the Community Office for Resource Efficiency (CORE). Construction was not completed until late in the summer, so this is the first full season that we have put it to use and we have grown more vegetables this winter and spring than ever before.  

The structure is a beautiful blend of time-tested design and new technologies. The initial layout and design of the building was informed by The Solar Greenhouse Book, published in 1978. It turns out that not much has changed with the sun in the last 40 years, so the information regarding designs to optimize the sun’s rays is still accurate today. The design includes proper orientation, ample insulation, extensive thermal mass, and high quality glazing materials. 

We took the 1978 designs a step further with some components inspired by current design and technology. We upgraded the glazing material and chose to use triple wall polycarbonate panels. These clear panels have a 10-year warranty and almost six times the R-value of polyethylene plastic. The 1978 design suggests several options for thermal mass and ultimately recommends water as the preferred option. While cheap, readily available, and still a good choice, water takes up a large amount of space in quantities sufficient to store the heat that we wanted. A quick calculation suggested that we needed around 3000 gallons of water, which would have taken up ¼ of our floor space. Instead, we opted for Phase Change Material, also known as PCM. This relatively new product offers better heat storage capacity than water, yet only takes up about ½ inch of space on the north wall and roof, leaving all of that valuable square footage available for plants. Lastly, we added a Ground to Air Heat Transfer System (GAHT) system, sometime referred to as a Climate Battery. This series of tubes and fans circulates excess warm air from the structure to the ground, where the soil stores heat. During cooler periods (like at night), the fans pull the heat from the ground to heat the air in the greenhouse. 

The seed propagation house has already produced several thousand seedlings and the first few rounds have already made their way into garden beds. Over 1400 kale, Swiss chard, and lettuce seedlings were transplanted outside in mid-March. Tomatoes, peppers, cucumbers, and basil are already in the one of the other hoophouses and more vegetables and flowers are getting ready for transplant. 

Available Products

• Full supply of our locally famous, pasture-raised, non-GMO, Animal Welfare Approved, delicious chicken eggs (With the longer days, the egg production is increasing daily!)
• Salad mix, arugula and kale are available in limited quantities.

Products can be purchased at Ranch during open hours. Eggs are available at Hallam Lake.

Please call at least one business day in advance to confirm availability or to place an order for pick-up.

~ Jason Smith, Rock Bottom Ranch Director