Dynamical edge effect factor determination for building components thermal characterization under outdoor test conditions in a PASLINK test cell: A methodological proposal

Abstract

The thermal characterization of building components in dynamic exterior conditions is crucial for understanding their real performance, particularly if they are passive or active solar elements. In this respect, the PASLINK methodology has stood out as an effective technique for outdoor testing due to its level of development and precision. It is based on the use of a calibrated test cell with interior walls covered by heat flow meters. The accurate determination of the heat flow through the envelope of the cell is essential for the subsequent thermal analysis of the passive/active solar component being tested. Although the walls of a PASLINK cell have a high thermal resistance and minimal thermal bridges, a higher heat flux is inevitable near the inner corners because of the edge effects. This variation is partially detected by heat flow meters, requiring correction factors accordingly named ‘edge effect factors’. Additional heat flow meters strategically arranged in some interior corners are used to determine these factors in a calibration test. The factors thus calculated are used as invariable values in subsequent cell tests. However, the skill and knowledge of the staff conducting the calibration test are fundamental, as human errors can affect this process. This proposal outlines a more objective and reliable new methodology to determine edge effect correction factors. It is based on applying correlations of instantaneous readings of heat flow meters. These correlations are obtained in an initial PASLINK calibration test, but are valid for all subsequent tests. The factors calculated in this way depend on instantaneous test readings and, for this reason, they are dynamic values perfectly adapted to each test. The calibration test of the cell called EGUZKI, located in Vitoria-Gasteiz (Northern Spain), is used to demonstrate the validity of the proposed method. With the current PASLINK calibration test methodology, the calibrated cell obtains a measurement error of 13%, while the proposed new dynamic methodology reduces this error to 6%. Although this new methodology is determined in the context of a PASLINK test cell, it is an extensive method applicable to the correction of heat flow measurements affected by edge effects in general.