Definition of an experimental procedure with the hot box method for the thermal performance evaluation of inhomogeneous walls

Abstract Research and development of high thermal insulation materials for the construction sector requires an accurate characterization of the wall's performance, since that is the main causes of thermal exchanges between the internal and external boundaries. This paper presents a test procedure developed within the EU Project EFFESUS for evaluating the steady-state thermal performance of a masonry wall. A large-scale mock-up of the inhomogeneous wall was tested in a guarded hot box (GHB) apparatus before and after the application of an aerogel-based material. The methodology proposed in this paper is structured in the following steps: (i) definition of the wall geometry and the percentage of stone and mortar, using walls’ photographic records and geometrical surveys; (ii) precise thermal characterization of the material used; (iii) hygrothermal assessment procedure based on infrared technology (IRT) survey, gravimetric test, and monitoring of the internal relative humidity (RH); (iv) steady-state and dynamic thermal simulation; and (v) detailed set-up of the test using the data retrieved from the thermal surveys and simulations. According to the results of IRT surveys and the dynamic simulations, the mock-up was divided into thermal homogeneous parts, verifying the uniformity of the surface temperature and the heat flux in an isothermal area. This approach was validated both for low and high energy performance walls. Results show that the thermal flux was reduced to one third after the application of the aerogel.

[1]  Alexandra Troi,et al.  The “Cost Optimality” Approach for the Internal Insulation of Historic Buildings , 2017 .

[2]  Rajendra Singh Adhikari,et al.  Experimental Measurements on Thermal Transmittance of the Opaque Vertical Walls in the Historical Buildings , 2012 .

[3]  Valentina Serra,et al.  Thermal insulating plaster as a solution for refurbishing historic building envelopes: First experimental results , 2015 .

[4]  Giorgio Baldinelli,et al.  Thermal transmittance measurements with the hot box method: Calibration, experimental procedures, an , 2011 .

[5]  Maria Concetta Di Tuccio,et al.  Characterization and thermal performance evaluation of infrared reflective coatings compatible with historic buildings , 2018 .

[6]  Bruno Daniotti,et al.  Performance evaluation of aerogel-based and perlite-based prototyped insulations for internal thermal retrofitting: HMT model validation by monitoring at demo scale. , 2016 .

[7]  Ákos Lakatos,et al.  Investigation of the moisture induced degradation of the thermal properties of aerogel blankets: Measurements, calculations, simulations , 2017 .

[8]  Arild Gustavsen,et al.  Aerogel insulation for building applications: A state-of-the-art review , 2011 .

[9]  Ecem Edis,et al.  Hot box measurements of pumice aggregate concrete hollow block walls , 2013 .

[10]  Umberto Berardi,et al.  Hygrothermal characteristics of aerogel-enhanced insulating materials under different humidity and temperature conditions , 2018 .

[11]  A. N. Fried,et al.  Thermal properties of a variable cavity wall , 2001 .

[12]  Ulrich Filippi Oberegger,et al.  Energy retrofit and conservation of a historic building using multi-objective optimization and an analytic hierarchy process , 2017 .

[13]  Jean-Jacques Roux,et al.  Reduced linear state model of hollow blocks walls, validation using hot box measurements , 2004 .

[14]  K. Ghazi Wakili,et al.  U-value of a dried wall made of perforated porous clay bricks Hot box measurement versus numerical analysis , 2003 .

[15]  Gongsheng Huang,et al.  Thermal performance and service life of vacuum insulation panels with aerogel composite cores , 2017 .

[16]  Marcus Bianchi,et al.  Three-Dimensional Numerical Evaluation of Thermal Performance of Uninsulated Wall Assemblies , 2011 .

[17]  S. Pavía,et al.  Thermal performance of a selection of insulation materials suitable for historic buildings , 2015 .

[18]  Umberto Berardi,et al.  Long-term thermal conductivity of aerogel-enhanced insulating materials under different laboratory aging conditions , 2018 .

[19]  José María Sala,et al.  Static and dynamic thermal characterisation of a hollow brick wall: Tests and numerical analysis , 2008 .

[20]  Marco Manzan,et al.  Experimental and Numerical Comparison of Internal Insulation Systems for Building Refurbishment , 2015 .

[21]  Cinzia Buratti,et al.  Optical, thermal, and energy performance of advanced polycarbonate systems with granular aerogel , 2018 .

[22]  Saffa Riffat,et al.  Optimizing insulation thickness and analysing environmental impacts of aerogel-based thermal superinsulation in buildings , 2014 .

[23]  Umberto Berardi,et al.  Aerogel-enhanced systems for building energy retrofits: insights from a case study , 2018 .

[24]  Pascal Henry Biwole,et al.  Hygrothermal performance of exterior walls covered with aerogel-based insulating rendering , 2014 .

[25]  Aitor Barrio,et al.  Thermal assessment of ambient pressure dried silica aerogel composite boards at laboratory and field scale , 2016 .