Abstract
Thermal infrared imaging is a valuable tool to perform non-destructive qualitative tests and to investigate buildings envelope thermal-energy behavior. The assessment of envelope thermal insulation, ventilation, air leakages, and HVAC performance can be implemented through the analysis of each thermogram corresponding to an object surface temperature. Thermography also allows the identification of thermal bridges in buildings’ envelope that, together with windows and doors, constitute one of the weakest component increasing thermal losses. A quantitative methodology was proposed in previous researches by the authors in order to evaluate the effect of such weak point on the energy balance of the whole building. In the present work, in-field experimental measurements were carried out with the purpose of evaluating the energy losses through the envelope of a test room experimental field. In-situ thermal transmittance of walls, ceiling and roof were continuously monitored and each element was characterized by its own thermal insulation capability. Infrared thermography and the proposed quantitative methodology were applied to assess the energy losses due to thermal bridges. The main results show that the procedure confirms to be a reliable tool to quantify the incidence of thermal bridges in the envelope thermal losses.
Highlights
Despite the application of highly insulating materials for building envelope, the overall building thermal performance could still be affected by local phenomena, e.g., thermal bridges, responsible for significant thermal losses [16]
IR thermography represents an acknowledged qualitative methodology aimed at investigating thermal discontinuities throughout buildings envelope and the presence-positioning of thermal bridges
Recent research efforts were aimed at developing quantitative techniques to analyze the effect of thermal bridges on building thermal-energy behavior
Summary
The energy requirement for buildings heating is progressively decreasing in the European Union thanks to the implementation of the new directives driving energy efficiency in construction [1].The growing interest in energy saving in the building sector is producing increasingly sophisticated investigation methods [2,3,4,5,6,7,8] and solutions consisting of new techniques [9] and materials for building envelope [10,11,12,13,14,15]. Despite the application of highly insulating materials for building envelope, the overall building thermal performance could still be affected by local phenomena, e.g., thermal bridges, responsible for significant thermal losses [16]. Several studies showed that thermal bridges may cause up to 30% of the extra-thermal losses through the envelope in winter, so increasing the energy requirement for heating [17]. Other effects of these local weak spots is the presence of differentially cooled areas around thermal bridges and the consequent development of molds and fungi, producing bad indoor air quality conditions [18,19,20]. This work makes use of the results of a previous quantitative study, aimed at defining the Incidence factor of the thermal bridges and its numerical validation, with the purpose to quantify the effect of thermal bridges in a continuous monitored dedicated full-scale building experimental setup
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