The report presents a new version of the EPA/Southern Research Institute electrostatic precipitator (ESP) model. The primary difference between this and the standard (Revision 3) versions is in the treatment of the particulate space charge. Both models apply the Deutsch equation to narrow particle size bands over short ESP lengths to determine collection efficiency. The standard version estimates space charge by a formula which predicts an effective mobility for ions and particles and a reduced ion density for particle charging. The estimated values are used to calculate the electric field at the plate and the particle charge, both required for the Deutsch equation. However, in the new version the particulate space charge is treated explicitly, allowing the interrelation of the particle charge and electric field calculations. The charge and field calculations are alternated until they become self-consistent within each length increment of the ESP. Self-consistency occurs when the charge used for the space charge in the field calculation is the same as that calculated using the results of the field calculation. The explicit treatment of the space charge directly relates the particle charge and electric field calculations, and therefore the collection efficiency calculation, to the dust load present in the gas stream. The report gives operating instructions for the new model.