In Situ Measurement of Wall Thermal Properties: Parametric Investigation of the Heat Flow Meter Methods through Virtual Experiments Data

Energy retrofit of existing buildings is based on the assessment starting performance envelope. The procedure for in situ measurement thermal conductance described ISO 9869-1:2014, which provides two techniques data processing: average method (AM) and dynamic (DM). This work studies their effectiveness using virtual from numerical simulations a finite difference model applied to different wall kinds, considering winter summer boundary conditions alternatively (Italian Milan-Linate TMY). estimated conductances are compared reference theoretical values. main purposes are: (i) defining shortest test duration that acceptable results; (ii) assess reliability criteria provided by standard evaluate quality; (iii) sensitivity both methods variables such as properties, others more specific DM (namely, number time constants linear equations). AM always estimates (−3.1% ÷ 10% error), with better outcomes when indoor heat flux considered, except highly insulated wall, but not effective summer, despite fulfillment acceptance wall. improvements seasons (0.05% 8.6% absolute values most samples, requires shorter sampling periods, even below 3 days limit suggested standard. confidence interval indicated 9869-1:2014 reliable measurements sensitive equations, left user’s discretion without strict indications. suggests possible approach overcoming this issue, deeper future investigation.