Before and during the 1990 winter, the small former DNF and paint storage building was gutted, reinsulated and vapor sealed, and equipped with a vestibule. The walls were lined with aluminum foil. The heat was provided by 2 existing Chromalox heaters. There was a single nutrient system that circulated through the 2 levels. Conditions were maintained at 68°F and 70% humidity. it worked well, the main crops were lettuce, peppers and tomatoes, although sprouts, kale, oregano and strawberries were also planted. The full story is in this article Greenhouse Gardening at the South Pole by Michelle Rogan-Finnemore, from the summer 1992 Growing Edge magazine.
At left is a rather poor image of the inside of the greenhouse. It illustrates the aluminum foil lined walls as well as the small size of the chamber, but remember there were only 20 winterovers on station. The system worked well and provided not only fresh food but also an environment where folks could spend time enjoying the humidity and sunlight. A portable tanning bed was installed, along with sun lamps on timers, something that the current growth chamber in the elevated station does NOT have.
This information is thanks to Michelle Rogan-Finnemore; the images above are from her referenced Growing Edge article. Michelle, and her husband Michael, wintered in 1990 and were heavily involved in this project. I got to know them on station during the 1989-90 summer.