Citation: Pedroso, M.; Silvestre, J.D.; Gomes, M.d.G.; Hawreen, A.; Bersch, J.D.; Flores-Colen, I. Integrated Performance Evaluation of Aerogel-Based Fibre-Enhanced Thermal Renders Applied on Building Walls. Gels 2023, 9, 898. https://doi.org/10.3390/ gels9110898 Academic Editor: Miguel Sanchez-Soto Received: 11 September 2023 Revised: 29 October 2023 Accepted: 3 November 2023 Published: 13 November 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). gels Article Integrated Performance Evaluation of Aerogel-Based Fibre-Enhanced Thermal Renders Applied on Building Walls Marco Pedroso 1 , José Dinis Silvestre 1 , Maria da Glória Gomes 1 , Ahmed Hawreen 1,2,3 , Jéssica D. Bersch 1,4 and Inês Flores-Colen 1, * 1 Civil Engineering Research and Innovation for Sustainability (CERIS), Departamento de Engenharia Civil, Arquitetura e Ambiente (DECivil), Instituto Superior Técnico (IST), Universidade de Lisboa, Av. Rovisco Pais, 1049-001 Lisbon, Portugal; marco.pedroso@tecnico.ulisboa.pt (M.P.); jose.silvestre@tecnico.ulisboa.pt (J.D.S.); maria.gloria.gomes@tecnico.ulisboa.pt (M.d.G.G.); hawreen.a@gmail.com (A.H.); jessica.d.bersch@tecnico.ulisboa.pt (J.D.B.) 2 Department of Highway and Bridge Engineering, Technical Engineering College, Erbil Polytechnic University, Erbil 44001, Iraq 3 Department of Civil Engineering, College of Engineering, Nawroz University, Duhok 42001, Iraq 4 Núcleo Orientado para a Inovação da Edificação (NORIE), Programa de Pós-Graduação em Engenharia Civil: Construção e Infraestrutura (PPGCI), Universidade Federal do Rio Grande do Sul (UFRGS), Av. Osvaldo Aranha, 99, Porto Alegre 90035-190, Brazil * Correspondence: ines.flores.colen@tecnico.ulisboa.pt Abstract: In this work, aerogel renders were enhanced with fibres for use in new building walls, emphasising a Mediterranean climate. The main novelty of the study relies on an integrated evalua- tion of the aerogel-based fibre-enhanced thermal renders from environmental, energy and economic approaches. Therefore, optimum insulation thicknesses, life cycle savings, payback periods, abiotic depletion potential from fossil fuels (ADP-ff) and global warming potential (GWP) impacts were quantified as a function of the energy consumption. The cost optimisation of aerogel-based renders enabled a reduction from 2477.4 to 1021.7 EUR·m −3 for the reference formulation, and the sisal- optimised render led to the best-integrated performance. A higher DD* (degree-days equivalent) led to higher optimum thicknesses (the Azores required 0.02 m and 0.01 m and Bragança 0.06 m and 0.03 m for cost-optimised and non-optimised thermal renders with sisal fibre, respectively). The optimum thickness related to the ADP-ff and GWP impacts was higher, 0.04 m for the Azores and 0.09 m for Bragança. A steeper decrease in the annual energy consumption occurred for thermal renders up to 0.02 m in the Azores and 0.04 m in Bragança. Aerogel-based fibre-enhanced thermal renders had benefits, mainly from 600 DD* onwards. Keywords: ADP-ff; aramid fibres; cost optimisation; GWP; optimum insulation thickness; payback period; silica aerogel; sisal fibres; thermal render 1. Introduction The concerns towards climate change have led to several mitigation plans, such as the objective of making the climate neutral by 2050 in the European Union, with a significant milestone on emission reduction by 2030. This is in agreement with the Paris Agreement [1], with the main action lines related to reducing non-renewable energy sources and emissions of greenhouse gases [2]. However, simultaneously, concerns referring to the indoor comfort of building’s users [3–5] have led to higher levels of heating and cooling energy consumption, which have made the European built environment responsible for approximately 40% of the total energy consumption and 36% of CO 2 emissions [3,4]. Therefore, urgent solutions are needed to reduce the resulting impacts and achieve climate- neutral objectives. Gels 2023, 9, 898. https://doi.org/10.3390/gels9110898 https://www.mdpi.com/journal/gels