A comparison of standardized calculation methods for in situ measurements of facades U-value

Abstract In recent years, a growing concern has been how to determine the actual thermal behaviour of facades in their operational stage, in order to establish appropriate energy-saving measures. This paper aims at comparing standardized methods for obtaining the actual thermal transmittance of existing buildings’ facades, specifically the average method and the dynamic method defined by ISO 9869-1:2014, to verify which best fits theoretical values. The paper also aims to promote the use of the dynamic method, and facilitate its implementation. Differences between the theoretical U-value and the measured U-value obtained using the average and dynamic methods were calculated in three case studies, and then compared. The results showed that differences between the theoretical and the measured U-value were lower when the dynamic method was used. Particularly, when testing conditions were not optimal, the use of the dynamic method significantly improved the fit with the theoretical value. Moreover, measurements of the U-value using the dynamic method with a sufficiently large dataset showed a better fit to the theoretical U-value than the results of other dynamic methods proposed by authors. Further research should consider the optimum size of the dataset to obtain a measured U-value that is correctly adjusted to the theoretical U-value.

[1]  Elvira Ianniello,et al.  U-value in situ measurement for energy diagnosis of existing buildings , 2015 .

[2]  Marta Gangolells,et al.  Classifying system for façades and anomalies , 2016 .

[3]  M. R. Heras,et al.  Application of different dynamic analysis approaches to the estimation of the building component U value , 2009 .

[4]  Piotr Jaskuła,et al.  Durability of Asphalt Concrete Subjected to Deteriorating Effects of Water and Frost , 2016 .

[5]  Chao Wang,et al.  Noninvasive Residential Building Envelope R-Value Measurement Method Based on Interfacial Thermal Resistance , 2016 .

[6]  Paul Baker,et al.  Technical Paper 10: U‐values and traditional buildings - In situ measurements and their comparisons to calculated values , 2011 .

[7]  Roberto Ricciu,et al.  Comparing different approaches to in situ measurement of building components thermal resistance , 2011 .

[8]  Didier Defer,et al.  Thermal characterization of homogeneous walls using inverse method , 2014 .

[9]  António Tadeu,et al.  In-Situ Thermal Resistance Evaluation of Walls Using an Iterative Dynamic Model , 2015 .

[10]  Luai M. Al-Hadhrami,et al.  In situ measurement of thermal transmittance and thermal resistance of hollow reinforced precast concrete walls , 2014 .

[11]  S. Corgnati,et al.  Use of reference buildings to assess the energy saving potentials of the residential building stock: the experience of TABULA Project , 2014 .

[12]  M. Founti,et al.  Thermal performance of a building envelope incorporating ETICS with vacuum insulation panels and EPS , 2014 .

[13]  Terry Williamson.  Predicting building performance: the ethics of computer simulation , 2010 .

[14]  Dario Ambrosini,et al.  A comparison between thermographic and flow-meter methods for the evaluation of thermal transmittance of different wall constructions , 2015 .

[15]  P. Amparo López-Jiménez,et al.  Thermal behavior analysis of different multilayer façade: Numerical model versus experimental prototype , 2014 .

[16]  Pieter de Wilde,et al.  The gap between predicted and measured energy performance of buildings: A framework for investigation , 2014 .

[17]  Tadj Oreszczyn,et al.  Inferring the thermal resistance and effective thermal mass of a wall using frequent temperature and heat flux measurements , 2014 .

[18]  Tadj Oreszczyn,et al.  Solid-wall U-values: heat flux measurements compared with standard assumptions , 2015 .

[19]  S. Standard.  GUIDE TO THE EXPRESSION OF UNCERTAINTY IN MEASUREMENT , 2006 .

[20]  Giorgio Baldinelli,et al.  Evaluating in situ thermal transmittance of green buildings masonries—A case study , 2014 .

[21]  Changhai Peng,et al.  In situ measuring and evaluating the thermal resistance of building construction , 2008 .

[22]  Michela Chiogna,et al.  A comprehensive experimental approach for the validation of quantitative infrared thermography in the evaluation of building thermal transmittance , 2015 .

[23]  Claudia Guattari,et al.  In Situ Thermal Transmittance Measurements for Investigating Differences between Wall Models and Actual Building Performance , 2015 .