Software tool for thermal design & energy simulation related to buildings. In design mode, APACHE covers the calculation of heating, cooling and latent room loads, the sizing of room units, internal comfort analysis and codes/standards checks. In simulation mode, APACHE performs a dynamic thermal simulation using hourly weather data. Linked modules deal with the performance of HVAC plant and natural ventilation. APACHE is a component of the IES Virtual Environment, an integrated computing environment encompassing a wide range of tasks in building design.