‘The growth accelerator’ is an experimental greenhouse that was designed and built by Michael Jantzen in 1986 for the Missouri botanical garden in St. Louis, Missouri. The small mobile structure functioned as a public exhibit that explored how to grow plants more energy-efficient in cold climates. The modular construction could also be located almost anywhere since it was transported fully assembled on a truck bed. It was simply set elevated above the ground onto attached self-leveling supports.
The structure was made of five sections: four low-profile insulated glazed sections, and one taller insulated section. The four lower-profile sections were designed to be just large enough to contain the plants, and the one taller section was just big enough to contain one person who attended to the needs of the plants. This was done in order to reduce the amount of heating and/or cooling energy needed to maintain the correct temperature for the plants by reducing the contained volume around them, and the one maintenance person.
Two of the low-profile glazed sections could be slid open over the top of the other two in order to ventilate the structure during the summer. In addition, a shade cloth could be attached over the low-profile sections, and an exhaust fan could be used for additional cooling.
During long winter nights, the plants that were contained on telescoping stainless steel benches could manually or automatically be pulled with a small electric gear motor into a heavily insulated chamber to protect them from the cold. These benches also contained large amounts of a special thermal mass material that absorbed solar heat during the day, and at night that heat was used to keep the plants warm inside of the glazed sections of the greenhouse, or inside of the insulated chamber.
A small computer was used to control the movement of the plants. It could decide when or if the plants should be automatically moved out of the insulated chamber and into the glazed section when the light level and temperature were correct. As an example, on a cold cloudy day with low light levels and low temperatures, the computer may decide to leave the plants in the insulated chamber and turn on the electric grow lights that were mounted above each of the telescoping benches. Those decisions were based on the use of the least amount of energy to keep the plants alive. The computer could also automatically water the plants.
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