Exhaust-Only Ventilation Exhaust-only ventilation is the reverse of supply-only ventilation; stale air leaves the building from a known location (through exhaust fans ducted to the outdoors) and outdoor air enters the building from an unknown location.
In the 1960s, the Soviet Union began to prepare the Warsaw Pact for its internal function of keeping the NSWP member states within the alliance. The Soviet Union took a series of steps to transform the Warsaw Pact into its intra-alliance intervention force.
The purpose of the berlin wall was... Russia was communist and wanted to spread their communist ideas. So after russia and the U.S. split germany, a wall was put up over night by the russians to prevent people from leaving the east side.