Experimental Investigation of Heat Transfer during Night-Time Ventilation

Nikolai Artmann, Rasmus Lund Jensen, H. Manz, Per Heiselberg

Research output: Contribution to journalJournal articleResearchpeer-review

34 Citations (Scopus)

Abstract

Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes more efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.
Original languageEnglish
JournalEnergy and Buildings
Volume42
Issue number3
Pages (from-to)366-374
Number of pages9
ISSN0378-7788
DOIs
Publication statusPublished - 2010

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Ventilation
Heat transfer
Air
Ceilings
Flow rate
Cooling
Thermal comfort
Engineers

Keywords

  • Passive cooling
  • Night-time ventilation
  • Experiments
  • Heat transfer
  • Temperature efficiency
  • Mixing ventilation
  • Displacement ventilation

Cite this

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title = "Experimental Investigation of Heat Transfer during Night-Time Ventilation",
abstract = "Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes more efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.",
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Experimental Investigation of Heat Transfer during Night-Time Ventilation. / Artmann, Nikolai; Jensen, Rasmus Lund; Manz, H.; Heiselberg, Per.

In: Energy and Buildings, Vol. 42, No. 3, 2010, p. 366-374.

Research output: Contribution to journalJournal articleResearchpeer-review

TY - JOUR

T1 - Experimental Investigation of Heat Transfer during Night-Time Ventilation

AU - Artmann, Nikolai

AU - Jensen, Rasmus Lund

AU - Manz, H.

AU - Heiselberg, Per

PY - 2010

Y1 - 2010

N2 - Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes more efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.

AB - Night-time ventilation is seen as a promising approach for energy efficient cooling of buildings. However, uncertainties in the prediction of thermal comfort restrain architects and engineers from applying this technique. One parameter essentially affecting the performance of night-time ventilation is the heat transfer at the internal room surfaces. Increased convection is expected due to high air flow rates and the possibility of a cold air jet flowing along the ceiling, but the magnitude of these effects is hard to predict. In order to improve the predictability, heat transfer during night-time ventilation in case of mixing and displacement ventilation has been investigated in a full scale test room. The results show that for low air flow rates displacement ventilation is more efficient than mixing ventilation. For higher air flow rates the air jet flowing along the ceiling has a significant effect, and mixing ventilation becomes more efficient. A design chart to estimate the performance of night-time cooling during an early stage of building design is proposed.

KW - Passive cooling

KW - Night-time ventilation

KW - Experiments

KW - Heat transfer

KW - Temperature efficiency

KW - Mixing ventilation

KW - Displacement ventilation

U2 - 10.1016/j.enbuild.2009.10.003

DO - 10.1016/j.enbuild.2009.10.003

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JO - Energy and Buildings

JF - Energy and Buildings

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ER -