1. A building controller configured to communicate with and control one or more components of an HVAC system of a building, the building controller comprising: an input/output port for sending and/or receiving data over a network: a memory for storing one or more operating parameters including one or more user-specified air quality thresholds; a user interface; and a controller coupled to the input/output port, the memory, and the user interface, the controller configured to receive and accept one or more user-specified air quality thresholds from a user via the user interface, the controller further configured to receive a first signal indicative of a measure of indoor air quality, the controller configured to receive a second signal indicative of a measure of outdoor air quality, the controller further configured to determine if ventilation of the building is desired based, at least in part, the one or more user-specified air quality thresholds stored in the memory and one or more of the measure of indoor air quality and the measure of outdoor air quality.