This report contains a description of an ongoing study of gravity currents for conditions which match those we expect to find in unwanted fires in buildings. A review is made of the pertinent literature and a description is given of the flow regimes which can exist for ideal gravity currents when viscous effects, heat transfer, and mixing are ignored. The influence of boundary conditions fixed by the method used to withdraw the fluid displaced by the current is given. Algebraic equations for the thickness of the current and the velocity of the head are derived for these ideal flows. The influences of viscosity and mixing are briefly discussed and the status of salt water and gas modeling experiments is given.