Construction and engineering of a created environment: Overview of the Biosphere 2 closed system

Biosphere 2 is a 1.27 ha virtually airtight environmental research facility located in Oracle, AZ. In this paper we emphasize material selection, supe r-structure, and sealing and testing methods to maintain a materially close d environment with a leak rate of approximate to 10% volumetric exchange pe r year, a specification some 1000 times the commercial building industry st andard. The capability to sustain closure was demonstrated over a period of similar to 3 years with human inhabitants reflecting one of the most uniqu e and sophisticated structural features of the facility distinguishing it f rom large greenhouses and phytotrons. A brief introduction to the diverse s tructures of the enclosed mesocosms is given including the wilderness and h uman-occupied areas. Key mechanical and electrical systems are summarized a nd recent modifications affecting the operation of Biosphere 2 as a closed system are described. (C) 1999 Elsevier Science B.V. All rights reserved.