TM 180 provides a physical of description the effect of ventilation on comfort and indoor air quality. Theoretical modelling of ventilation@ including zone and field methodologies@ is included@ with pointers to best practice guidelines for computational modelling. Heat transfer mechanisms@ humidity@ condensation@ jets and plumes are also described and explained. An overview of practical ventilation schemes is given and concepts such as thermal comfort@ indoor air quality@ mechanical and natural ventilation defined. A description is given of the mathematical basis for CFD (field) modelling of ventilation systems@ together with a discussion of computational meshing@ turbulence modelling@ and specification of boundary conditions. Mathematical models for water-vapour and airborne-particle transport@ atmospheric wind effects and flows through porous are also described.