Modelling of room air temperature profile with displacement ventilation

Natalia Lastovets*, Risto Kosonen, Panu Mustakallio, Juha Jokisalo, Angui Li

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)
90 Downloads (Pure)


An accurate temperature gradient calculation is essential for displacement ventilation (DV) system design, since it directly relates to the calculation of supply air flow rate. Several simplified nodal models were developed and implemented in the various building simulation programmes to estimate the temperature stratification in rooms with displacement ventilation. However, the most commonly used models do not take into account the types and locations of the heat loads in rooms with DV. As a result, the calculated air temperature in the occupied zone can defer from the real one by 2–3 °C, which causes poor thermal comfort and inadequate sizing of the ventilation and cooling systems.  In the present study, the nodal model was proposed to provide a simplified technique to predict the vertical temperature gradient in rooms with DV. In addition, the effect of the room height and locations of the indoor heat sources were studied for the typical office environment. The measurement data were compared with the existing nodal models and the proposed nodal model in terms of predicting the occupied zone temperatures. The presented nodal model demonstrates an accurate calculation of the temperature gradient for the typical heat loads and combinations of them.

Original languageEnglish
Pages (from-to)112-126
Number of pages15
JournalInternational Journal of Ventilation
Issue number2
Publication statusPublished - 2 Apr 2020
MoE publication typeA1 Journal article-refereed


  • Displacement ventilation
  • mixing height
  • nodal model
  • temperature gradient
  • thermal plume


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