The primary purpose of this study is to develop engineering methods to assess the impact of increased make-up air velocity in atria. The current restriction defined by NFPA 92 states that make-up air must not exceed 1 m/s during the operation of a mechanical smoke exhaust system. The make-up air required for atria during the operation of a mechanical smoke exhaust system must be provided by large areas of passive openings and mechanical ventilation, located below the smoke layer. This limitation not only limits creative and aesthetic atria designs but also presents significant costs. Many engineering designers use alternative methods to exceed the limit of the code, claiming that 1 m/s is too restrictive.