A number of interzonal models have been developed to calculate air flows and
pollutant transport mechanisms in both single and multizone buildings. A recent
development in multizone air-flow modeling, the COMIS model, has a number of
capabilities that go beyond previous models, much as COMIS can be used as
either a stand-alone air-flow model with input and output features or as an
infiltration module for thermal building simulation programs.

COMIS was designed during a 12 month workshop at Lawrence Berkeley
National Laboratory (LBNL) in 1988-89. In 1990, the Executive Committee of the
International Energy Agency's Energy Conservation in Buildings and Community
Systems program created a working group on multizone air-flow modeling, which
continued work on COMIS. The group's objectives were to study physical
phenomena causing air flow and pollutant (e.g., moisture) transport in multizone
buildings, develop numerical modules to be integrated in the previously designed
multizone air flow modeling system, and evaluate the computer code.

The working group supported by nine nations, officially finished in late 1997 with
the release of IISiBat/COMIS 3.0, which contains the documented simulation
program COMIS, the user interface IISiBat, and reports describing the evaluation
exercise.