###### Abstract
Indeed, as the range of available eco-materials expands and their properties exhibit a wide range of variation, such a selection process becomes increasingly complex and multifaceted. These arguments call for a rational and reproducible decision-making methodology for eco-material selection and ranking, covering objective aspects such as the cost and mechanical performance of the materials, but also less objective attributes such as expert opinions, impacts on sustainability, or aesthetics, in a rigorous and principled way. Indeed, the literature offers a wide variety of methodologies and frameworks designed to facilitate building material selection based on quite different criteria. For example, [PERSON] et al. [19] propose a systematic approach to sustainable material selection using the _choosing by advantages_ method, and they illustrate its application through the selection of ceiling tiles for construction. [PERSON] et al. [20] introduce a hybrid model for multi-criteria group decision-making that aids designers and engineers in selecting sustainable building materials. Their methodology is based on a novel linguistic approach for modeling and processing subjective information integrated within an consensus reaching methodology [21]. [PERSON] et al. [22] develop computational methodologies to facilitate the systematic selection of sustainable materials based on the integration of different evaluation criteria and analytical models to enable informed decision-making. [PERSON] et al. [23] propose a method to simulate the behavior of the sustainability parameters of building materials, to evaluate and select among a set of candidates using _system dynamics modeling_. [PERSON] et al. [24] propose an integrated approach for sustainable material selection that combines Life Cycle Sustainability Assessment, Building Information Modeling, and Multi-Criteria Decision Analysis. This paper aims to answer the research question of how to make a rational decision when choosing the most appropriate sustainable building material. More specifically, the main research objective is to develop a quantitative group decision-making methodology for structural material selection based on qualitative sustainability attributes. To achieve this, a rational methodology for multiple-criteria large-scale group decision-making under uncertainty in application to the selection of the most suitable eco-material among a set of candidates is developed. The proposed approach is grounded on a novel quantitative _strengths_, _weaknesses_, _opportunities_, _and threats_ (SWOT) analysis methodology, using survey data collected from a diverse group of experts and stakeholders that consider both the objective and subjective attributes of the materials in the context of their impacts on the United Nations' Sustainable Development Goals (SDGs). SWOT analysis is a qualitative method that lacks the capability to facilitate comparative analysis using quantitative metrics. In this sense, a domain-specific multiple-criteria decision-making (MCDM) model is developed along with the adoption of novel mixed-behavior aggregation functions, which are able to capture the dual nature and interrelationships between the surveyed SWOT factors accounting for the uncertainty in the data. The proposed methodology is demonstrated using data from three candidate eco-materials, namely _rammed earth_, _hempcreate_, and _ferrock_. The experts and stakeholders involved in the survey include engineering academics and practitioners in different countries. The results demonstrate the suitability of the proposed methodology in selecting and ranking among a set of candidate eco-materials by aggregating heterogeneous and subjective information from survey data and transforming it into quantitative scores that allow for rational decision-making. Importantly, the proposed methodology for group decision-making is generic and can be easily adapted to different disciplines and selection processes by simply adapting the required SWOT analysis.