Design Recommendations

The 8-Foot Rule

All windows for natural ventilation should be positioned at least eight feet above the finished floor. Any windows below eight feet MUST have security screens installed to protect the building occupants.


  • Prevent entrapment issues and potential bodily harm to occupants
  • Window movements seem arbitrary to occupants
  • Fall protection
  • Optimize ventilation in the space

Wind-Induced Ventilation

  • To maximize wind-induced ventilation, the ridge of a building should be positioned perpendicular to the summer winds.
  • Regional wind “rose” diagrams are available from NOAA but can differ from remote building sites.
  • For winter winds often coming from the north, a windbreak of evergreen trees could help to reduce cold winds.

Supply and Exhaust

  • Every room should have two separate supply and exhaust vents. Exhaust vents should be positioned high above the supply inlets to maximize the stack effect.
  • Stagger vents to improve the mixing of air.

Internal Airflow

  • Airflow in and out of the building is paramount, but airflow between rooms must also be considered to maximize ventilation.
  • When possible, interior doors should be designed to be left open to encourage ventilation. The use of interior louvers or transoms can also accomplish this.

Free Air Movement

  • A window does not need to open 90 degrees to optimize the air flow. In fact, most control systems need only operate within a few inches to gain desirable results. Once the dimensions of the window opening total the square area of the vent, the maximum air movement has been achieved.