The project is motivated by a desire to estimate site-specific climate data for heating, ventilating, and air-conditioning (HVAC) design within urban areas. One of the goals of Phase I of this project, as stated in the Work Statement (ASHRAE 1989), is to select a "first generation" simulation model to determine the specific variation of climate from one site to another within a given metropolitan area. This document describes the scope and operation of the selected model. The model selected for the project was developed by Carlson and Boland (1978). The selection process and recommendations for Phase II development are described in the project document entitled Model Selection and Phase II Recommendations (ASHRAE 1992).