The control of outdoor air intake rates in mechanically ventilated bldgs. based on indoor carbon dioxide (CO2) levels, often referred to as CO2 demand controlled ventilation (DCV), has the potential for reducing the energy consumption assoc. with bldg. ventilation in commercial and institutional bldgs. CO2 DCV has been studied for 20+ years, but questions still remain re: the actual energy savings potential as a function of climate, ventilation system features, and bldg. occupancy. In addition, questions exist as to the indoor air quality impacts of the approach and the best way to implement CO2 DCV in a given bldg. This report presents a state-of-the-art review of CO2 DCV technology and application incl. discussion of the concept and its application, and a literature review.