Catalogue

UV-PRC003-EN 19
Application Considerations
Dynamic Air Barrier
In areas that contend with colder climates for a significant period of time, a school may wish to
employ a dynamic air barrier package. With this dynamic (draft) barrier system, the cold air is
captured off of the window, and drawn into the classroom unit ventilator’s normal airflow cycle.
The unit ventilator treats/warms the air as if it were part of a return-air makeup system. This
captured air is then discharged into the space providing comfort to the classroom’s occupants.
This draft barrier shield should be utilized when:
• Almost 50 percent of the wall includes windows.
• Outside air temperatures fall below 35°F for a significant period of time
• Or, in retrofit applications where the windows are of a single pane thickness.
Outdoor Air Preconditioning
Conditioning the large amounts of outdoor air required for proper classroom ventilation can
significantly increase building cooling and heating loads. It also raises the system’s first cost and
operating cost. One way to reduce the impact of the outdoor air load on the unit ventilator is to use
energy recovered from the exhaust air stream to precondition the outdoor air as it’s brought into
the building.
A total-energy recovery (enthalpy) wheel consists of a revolving cylinder filled with a desiccant-
coated medium suitable for sensible and latent (moisture) heat transfer, Figure 16, p. 20. The
Figure 14. Reheat system and auto fan speed adjustment
Auto Fan Speed Adjustment with Tracer ZN520
Reheat System
Figure 15. Dynamic air barrier
Unit Ventilator
Captured
Cold Air
Draft Barrier and OA Preconditioning
UV-PRC003-EN.book Page 19 Tuesday, June 4, 2013 8:59 PM