The atrium size and building code of a cardiovascular facility in a northern climate required a large amount of outdoor air (OA) to be supplied to the atrium, according to an article on the Consulting- Specifying Engineer website.

The five-level, 400,000-square-foot cardiovascular center had tight site constraints and connections to adjacent buildings. This created the need for planning that placed the building air-handling units and fans on level five in a two-level mechanical room, with supply and return ductwork routed vertically in chases to the levels below, the article said. 

Building pressurization and ventilation were satisfied through the make-up air requirements with the HVAC design incorporating two OA-pretreat units. 

An additional function of these units was to provide treated make-up air to the atrium in locations and at velocities that met code requirements related to a potential fire origin in the atrium. 

Read the article.