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Location: St. Louis, Missouri, USA
Completion Date: 1959, 1990 (renovation)
Cost: $700,000 ($6 million renovation)
Diameter: 175 feet
Materials: Plastic (original design), aluminum, glass
Engineer(s): Paul Londe (original); Marshall, Tyler, Rausch LLC; Morgan & Assoc.; Ross & Baruzzini Inc. (renovation)
The Climatron, the major attraction of the Missouri Botanical Garden in St. Louis, is said to be the first geodesic dome ever used as a greenhouse. In 1959, Frits W. Went, then director of the Garden, wanted engineers to build a big, open, clear structure that would house a laboratory. In this laboratory, he wanted to play with air circulation, temperature, and humidity and grow a number of tropical plants. Went chose a geodesic dome, a design inspired by architect-engineer Buckminster Fuller, and he coined the name "Climatron" to emphasize the controlled climate in the greenhouse.
Unfortunately, Went wasn't concerned with the permanence of his structure. Over time, the Climatron began to fall apart. The dome's aluminum frame warped, allowing heat to escape and condensation to form within the dome. The plastic panes mounted on the aluminum frame were never meant to hold up more than five years, 10 at the most. By the mid-1980s, they were discolored and leaking.
In 1988, the Climatron was closed for a $6 million renovation in which all of the plastic panes were replaced with glass. Glass is more expensive than plastic, but it requires less maintenance over time. But because glass weighs an extra four pounds per square foot than plastic, engineers had to come up with a stronger, more rigid dome design. How did they do it? They built a dome within a dome! The outer structural frame consists of intersecting aluminum pipes, six inches in diameter. Two feet inside the outer frame, connected to it by rods, is another rigid frame of aluminum.Here's how this dome stacks up against some of the biggest domes in the world.
(diameter, in feet)