Karen- The Ventilation deck location, simply put, answers this question: "Where does the ventilation air go?" So, if it is "room direct", it means the ventilation air enters the room directly (ie separate ductwork than the supply air). If it is the common entry of "return outdoor/deck" this means that the outdoor air enters the AHU and mixes with the return air (as is quite common). The field is also available under the "Dedicated OA tab" (it is the same entry actually). Also, in my opinion, there is no better way of understanding this entry than to look at the help file (hit F1 at the advanced screen and click "ventilation deck location"). If the diagram is confusing to you, just stick to the definitions. I would say that - in 90% of buildings, the deck location is either "return/outdoor air" or "room direct", but it would naturally depend on the design firm, and building types. Usually the default for a system is the best choice, and there are large a number of different combinations, but that's all I can answer based on the question. Best Regards, Bob Fassbender Energy-models.com On Wed, Sep 19, 2012 at 3:07 PM, wrote: