Key outcomes:

  • Thermal comfort optimised throughout atrium
  • HVAC energy use minimised

Thermal stratification and localised heat sources within buildings can impose complex and interesting loads on building cooling and heating systems. Numerical simulations can provide quick answers to questions regarding the effectiveness of different HVAC systems and identify any deficiencies before they are installed.

In this example Synergetics was asked to model the transmitted heat load through a glass atrium roof on a hot summer day. The goal was to determine the resultant temperature gradients within the building, and determine if they would result in uncomfortable differences in temperature between floors.

simulated thermal stratification in a building with heat entering through the glass roof of the atrium.

Figure 1: CFD simulations indicated that high temperatures would be constrained to the roof cavity.

CFD modelling revealed that, with the planned ventilation systems, the roof cavity would be several degrees warmer than the ambient temperatures, but the high temperature regions would not extend down to the level of occupants on the top floor. Within occupied parts of the building temperature differences of less than 1ºC will occur, resulting in comfortable conditions for all occupants.  Based on this advice the building was successfully built with an adequate cooling system, without the need to over design it to address the previously unknown thermal stratification problems.

Looking up towards the atrium roof. Image resized and reproduced under the creative commons license - https://creativecommons.org/licenses/by-sa/2.0/ . Original photographer – Mal Booth https://www.flickr.com/photos/malbooth/

Figure 2. Looking up towards the atrium roof.