ESTGV - DEC - Artigo em revista científica, indexada ao WoS/Scopus
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- A contribution for the quantification of the influence of windows on the airtightness of Southern European buildingsPublication . Almeida, Ricardo; Ramos, Nuno M.M.; Pereira, Pedro F.Adequate airtightness levels are fundamental for the indoor environmental quality and energy efficiency of buildings. The quantitative characterization of expected leaks of common building elements is useful for practitioners that intend to improve building enclosures for airtightness optimization. This study intends to contribute to the quantification of the permeability of windows with a focus on the Southern European context of low airtightness in heavy construction buildings, where windows play an important role. A large experimental investigation was therefore carried out in 23 spaces, establishing three possible set-ups (nothing sealed, window sealed and window and roller-shutter sealed), using the fan pressurization method. A total of 104 tests were performed. Results revealed that the windows’ permeability indices ranged from 4.8 to 96.4 m3/(h m2) and from 1.2 to 30.8 m3/(h m), with average values of 28.7 m3/(h m2) and 8.9 m3/(h m), the roller-shutter contribution can be highly variable; also the year of construction, the frame material and the opening system are the key parameters for the airtightness of windows
- Parametric Analysis of Steel Studs to Reduce Thermal Bridges in Light Steel Framing Construction SystemsPublication . Langner, Marcelo; Soares, Thais A.; Figueiredo, Antonio; Almeida, Ricardo; Vicente, RomeuThermal bridges significantly affect the thermal performance of light steel framing systems due to the high thermal conductivity of steel. The objective of this study is to identify modifications on the steel profiles to reduce heat flux and improve the thermal resistance of both single- and double-layer wall panels. Three approaches were analyzed: (i) slotted steel studs, (ii) integration of less-conductive materials into the web section, and (iii) modifications to web geometry. A numerical model was calibrated based on experimental data and used to perform dynamic simulations with different configurations. Results show that incorporating less-conductive materials, such as rigid polyamide, achieved a heat flux reduction of up to 98%, while optimized slotted patterns reduced heat flux by up to 90%. The results also demonstrated that all web modifications effectively reduced heat flux through the wall, with approaches (i) and (ii) showing the greatest impact. The shape of the slots also has an important impact on the heat flux. The most effective strategy for enhancing the thermal performance of the steel studs was the use of a less-conductive material.