Estimating concentrations in plumes released in the vicinity of buildings: model development

A model is developed for near-field diffusion of effluents released on and near buildings. The model consists of low- and high-speed diffusion increments to the dispersion parameters in a Gaussian plume model. Building wake turbulence and diffusion data are used to evaluate model parameters. These data indicate that the low wind speed diffusion increment is both appropriate and necessary. They also indicate that the high-speed increment is appropriate, but that it is unnecessary. A companion paper compares model concentration predictions with measured concentrations, with concentrations predicted by standard wake models, and with concentrations predicted by alternative, non-Gaussian models designed to estimate bounding concentrations in building wakes. The model is shown to be conservative and predict concentrations in the vicinity of buildings better than other models.