With the need for better understanding of methods for estimating energy requirements for heating and cooling of buildings, the Task Group on Energy Requirements for Heating and Cooling of ASHRAE developed procedures for simulation of HVAC equipment and systems and procedures for calculation of load profiles and energy requirements. In order to verify or modify these procedures, four test sites were under consideration for a field study. The Pollock Undergraduate Library at The Pennsylvania State University, University Park, Pa., was one of the four buildings to be studied. Involvement in the initial study included the development of a system simulation for the heating and cooling of this particular building. The results of that development, are the subject of this paper.