Impact of Air Distribution on Heat Transfer during Night-Time Ventilation

Per Heiselberg, Nikolai Artmann, Rasmus Lund Jensen, Heinrich Manz

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Passive cooling by night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in prediction of cooling potential and consequenses for thermal comfort restrain architects and engineers from applying this technique. Heat transfer at internal room surfaces determines the performance of night-time ventilation. In order to improve predictability, heat transfer mechanism in case of either mixing or displacement ventilation has been investigated in a full scale test room with an exposed ceiling as the dominating thermal mass. The influence of air distribution principle, air flow rate and inlet air temperature were investigated. Results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher airflow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes most efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.
Original languageEnglish
Title of host publicationROOMVENT 2009 : Proceedings of the 11th International ROOMVENT Conference
EditorsKwang-Woo Kim, Dong-Won Yoon, Myoung Souk Yeo, Hyeun-Jun Moon, Cheol-Soo Park
Publication date2009
Publication statusPublished - 2009
EventThe International Conference on Air Distribution in Rooms : ROOMVENT - Busan, Korea, Republic of
Duration: 24 May 200927 May 2009
Conference number: 11


ConferenceThe International Conference on Air Distribution in Rooms : ROOMVENT
CountryKorea, Republic of

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