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Walls This article originally appeared in the July/August 2008
issue of Home Energy Magazine. July 01, 2008 Gypsum. It’s not
just for Twinkies. The mineral, a semi hydrous form of calcium
sulfate, with many uses from Plaster of Paris to Chinese
Medicine and even Twinkies, is mined all over the world. It’s
most popular use is in the most prevalent of the building
materials, sheetrock, or drywall. Invented in 1917, when energy
was cheap, sheetrock is like other energy-intense concoctions of
its time, a miracle invention that revolutionized home-building,
making it much easier than prevailing practices. But its
manufacture owes a full 25% to 50% of its costs to energy. It
joins its sister materials glass, steel, and cement in being a
major part of the problem of greenhouse gases. To make
sheetrock, gypsum is heated in large natural gas kilns to about
300°F (coughing lots of C02 into the sky), and then dried
(again, using natural gas). Additives are m