Buoyancy (or stack) ventilation is powered by heat generated inside buildings (from people, computers and so on). This Demonstration shows how to size vents at each story so that everyone gets the same flow rate of fresh air and experiences the same temperature relative to the outdoors. We consider a building with up to six stories plus an atrium. Engineering guidelines recommend a minimum of 10 liters per second of fresh air per person in an office environment.
 A. Acred and G. R. Hunt, "Stack Ventilation in Multi-storey Atrium Buildings: A Dimensionless Design Approach," Building and Environment, 72, 2014 pp. 44–52. doi:10.1016/j.buildenv.2013.10.007.
A version of this article can be obtained for free by downloading the following Ph.D. thesis (see chapter 4):
 A. Acred, "Natural Ventilation in Multi-storey Buildings: A Preliminary Design Approach," Ph.D. thesis, Civil and Environmental Engineering, Imperial College London, London, 2014. doi:10.25560/34322.