On site thermal performance characterization of building envelopes: How important are heat exchanges with neighbouring zones

© 2017 The Authors. Published by Elsevier Ltd. Worldwide, the building sector represents the largest energy using sector, and it is still expanding. To reduce energy use of buildings, policy makers are increasingly demanding with regard to energy efficiency of buildings. Despite best planning effort, in practice some of these demands are not met: studies reveal that a building's energy performance on the design table might differ substantially from its performance when actually built. Typically, an important reason for this difference lies in the delivered quality of a building's insulating envelope. In this paper, we investigate the characterisation of the overall heat loss coefficient, H, in WK-1, of whole building envelopes on the basis of dedicated heating experiments performed on vacant houses. We focus on steady-state heating experiments performed on buildings that are either terraced or semi-detached and have a floor on ground or unventilated basement. We depart from an extended stationary heat balance, that in addition to heat exchanges between indoor and outdoor environments, also explicitly includes heat exchanges between indoor environment and conditioned neighbouring zones. The first is of interest as it characterizes H, the latter is of interest as it constitutes a phenomenon that is often ignored, but might corrupt the estimate of H significantly. We show that, for the test buildings considered in this paper, it is advisable to additionally measure heat flows towards neighbouring properties. On the basis of three test cases, we investigate the significance of such heat flows, as well as their influence on the accuracy and robustness of the estimated heat transfer coefficient, H.

Publication year:2017

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Authors from:Higher Education