Abstract
The reduction of unwanted heat losses across the buildings’ envelope is very relevant to increase energy efficiency and achieve the decarbonization goals for the building stock. Two major heat transfer mechanisms across the building envelope are conduction and radiation, being this last one very important whenever there is an air cavity. In this work, the use of aerogel thermal break (TB) strips and aluminium reflective (AR) foils are experimentally assessed to evaluate the thermal performance improvement of double-pane lightweight steel-framed (LSF) walls. The face-to-face thermal resistances were measured under laboratory-controlled conditions for sixteen LSF wall configurations. The reliability of the measurements was double-checked making use of a homogeneous XPS single panel, as well as several non-homogeneous double-pane LSF walls. The measurements allowed us to conclude that the effectiveness of the AR foil is greater than the aerogel TB strips. In fact, using an AR foil inside the air cavity of double-pane LSF walls is much more effective than using aerogel TB strips along the steel flange, since only one AR foil (inner or outer) provides a similar thermal resistance increase than two aerogel TB strips, i.e., around +0.47 m2∙K/W (+19%). However, the use of two AR foils, instead of a single one, is not effective, since the relative thermal resistance increase is only about +0.04 m2∙K/W (+2%).
Highlights
Regarding the localization of the reflective foils, three configurations were considered (Figure 2): (i) along the inner side of the air cavity; (ii) along the outer side of the air cavity; (iii) along both sides of the air cavity. These two elements were tested separately, as well as combined, resulting in a Regarding the localization of the reflective foils, three configurations were considered (Figure 2): (i) along the inner side of the air cavity; (ii) along the outer side of the air cavity; (iii) along both sides of the air cavity
This way the heat transfer by radiation is mitigated within the air cavity due to the existence of the aluminium reflective (AR) foils, and the conductive heat transfer is mitigated due to the existence of the thermal break (TB) strips
This section is divided into three parts
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. When there is an air cavity inside the wall, one effective way to improve the thermal performance is by reducing the heat transfer by radiation This could be achieved by using reflective low-emissivity paint or foil inside the air gaps of the building components [22,23]. As recently mentioned by Bruno et al [23], there is a very small number of research works related to thermal resistance improvement due to low-emissivity materials placed inside air cavities This fact is even more perceptible in LSF double-pane building elements. Energies 2021, 14, 6927 double-pane LSF wall (30 mm air gap) and compare the thermal resistance increase only due to aerogel TB strips and only due to AR foils, by performing measurements under laboratory-controlled conditions. That the various scenarios evaluated in this research work were based on previous papers from authors, namely reference [24] for the aluminium reflective foil scenarios and reference [17] for the thermal break strips
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
