All too often, when we ask for the “ventilation design basis” (1910.119(d)(3)(i)(E)) we are given some calculations from a 3rd party engineering group. These calculations demonstrate the fan sizing for the necessary air exchanges and flows; however, what these calculations do NOT provide us is the full design basis for the ventilation system. For me, the “design basis” begins with the ventilation intakes (i.e. where is the “fresh air” coming from). I turn to the International Mechanical Code (IMC) as my RAGAGEP for a baseline of any ventilation system. We can see the IMC even begins with “intake opening location” and some of you may be surprised as to what this code actually requires:
The Ventilation Design Basis begins with our intakes
