Keeping large buildings well ventilated has always been a challenge. In health care buildings especially, supplying clean fresh air is of utmost importance to prevent CO2 and other contaminants from accumulating. The additional pressures to minimize energy and heat loss add to the difficulties.
In the past, many buildings have tackled these issues by using mechanical ventilation systems, drawing in fresh air and extracting stale. But while this eliminates heat and energy loss by making structures airtight, it can result in poor air quality.