Embodiments of the present invention provide a system that estimates the value of a virtual sensor. The system first samples values for performance metrics using external sensors that are coupled to a system and internal sensors that are built into the system. Next, the system generates an inferential sensing model for the system from the sampled values. Then, during operation, the system samples values of performance metrics using the internal sensors and uses the inferential sensing model and the sampled values from the internal sensors to estimate the values of performance metrics for removed external sensors (i.e., virtual sensors).