The aim of this thesis is to develop a computer program to design and simulate air conditioning-comfort application of a selected building, for a year period, on an hourly basis. In order to carry out this study, a computer program named AHUSIM.m, is prepared with Matlab computing language. The design and simulation procedure starts with preparing the inputs like indoor, outdoor design states, zone cooling and heating loads, along with the general data for conditioning-comfort equipment. The program, in light of these input data, performs the plotting of the psychrometric processes -including the design and off design processes- on psychrometric charts, air conditioning-comfort system selection and calculating the response of this selected system at varying load conditions for a year. The program also calculates the energy requirements of parts of the selected system throughout the year. Furthermore, it lists dimensions of the parts of the air conditioning-comfort unit, the outdoor supply air and total air flow rates, air and water inlet and exit states. Using numerical tools for heating, ventilating and air conditioning (HVAC) process design and simulation, can improve energy economy and comfort which are the main criteria of HVAC engineering. In such an attempt, major concern is the interaction between the comfort and energy consumption. The program, by designing the system and deciding its behavior throughout a year / provides a means of automatic control considering comfort and energy economy. This program also provides a tool for comparison of different techniques for putting limits to the relation between comfort and energy consumption.