The Learn-HVAC project is an effort to use a large-scale building simulation as the base for an educational tool to teach a wide variety of people how heating, ventilating, and air conditioning systems work. These systems account for a substantial fraction of energy usage in this country and by many accounts are often not operated at efficiency levels that the systems are capable of (which varies tremendously depending on their age and design). HVAC systems are extremely complex internally so inefficient system operation can result from lack of knowledge or from malfunctions in system components that are not recognized. Learn-HVAC aims specifically at the HVAC complexity issue in its educational approach. Because buildings themselves are not suitable educational tools, a large-scale computer simulation is used to give people the experiential experience needed to develop an in-depth understanding of HVAC system operation. The thesis of this effort is that using such a simulation as part of an HVAC curriculum can enable a level of understanding that is not possible with conventional curricula.