The Passive House standard was originally developed in Germany, inspired by American pioneers like Wayne Schick and William Shurcliff, who explored the idea of making extremely energy-efficient buildings in the late 1970s and early 80s. The standard is now widely accepted throughout Europe, following a pilot program called Cepheus (Cost Efficient Passive Houses as EUropean Standards) in 2000, and the Germans are looking to make it building code in 2020. The Passive House Institute in Germany is the official authority of the standard worldwide. It was co-founded in 1996 by Dr. Wolfgang Feist at the University of Darmstadt. In late 2007, the standard was introduced in the U.S. with the launch of the Passive House Institute U.S. (PHIUS). Since the standard has its roots in Europe, all energy modeling is done in metric format. This does not mean that it conflicts with building codes or construction methods in the U.S., as the numbers can be converted to the American standard and back. The important number to remember here is 15kWh per square meter and year (4,750BTU per square foot and year), which means up to 90% less energy used for space conditioning, i.e. heating and cooling.