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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. Quick answers regarding the effectiveness of different HVAC systems and identification of any deficiencies before installation can be provided by numerical simulations.

Synergetics was asked to model the transmitted heat load through a glass atrium roof on a hot summer day. The goal was to determine temperature gradients within the building and assess the potential for uncomfortable temperature differences between floors.

A cut plane through a multilevel building, with a large atrium. Contours of CFD modelled temperature are shown, with high temperatures only occurring in the roof cavity due to thermal stratification

Figure 1: CFD simulations showed that the roof cavity would constrain high temperatures.

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. The building was successfully built with an adequate cooling system based on this advice, without the need to over design it to address previously unknown thermal stratification problems.

A photo of the building atrium, showing the complex geometry with many levels

Figure 2. Looking up towards the atrium roof.

For further building CFD examples, see our sector page.