Convective heat transfer coefficient to estimate energy requirements of office buildings

Obyn, Sophie [UCL] Van Moeseke, Geoffrey [UCL]

The choice of surface convective heat transfer coefficient (CHTC) affects the evaluation of building’s thermal comfort and energy consumptions. The present work follows the study of Obyn and van Moeseke in 2015 [1] in which the impact of CHTC expressions used for the calculation of heating and cooling demands and loads of office buildings considering one type of surface at a time (wall, ceiling, floor) is investigated. In the present paper, the same methodology and hypothesis are considered but the impact of CHTC expressions on estimating energy requirements of office buildings is evaluated considering all surface types at a time (all surfaces of rooms). After analysis of these results, the main conclusion is that the choice of CHTC expression really impacts the evaluation of annual energetic demand, especially for heavy structures, and mean and maximum values of heating and cooling loads. Moreover, some identified expressions provide very different values of CHTC from other with a real impact on annual energetic demands calculated. These also lead to widely different values of mean and maximum heating and cooling loads that impact on the design of HVAC installations. The choice of CHTC is then really important and a constant value may not be used to evaluate energetic demands and heating and cooling loads of office buildings. After analysis of results obtained in the case of a standard office room, it is recommended to consider expressions provided by Min et al. [2] to do these evaluations.