## 3 Search Results and Classification
### Environmental Impacts  
In 31 studies, qualitative or quantitative aspects were reported, or statements were made regarding the environmental impacts associated with the use, application, or implementation of industrialized construction systems, predominantly focusing on data contributing to the carbon footprint category. Eighty-seven percent of the studies reported data on prefabricated systems and ten percent on modular systems, and only three percent provided data on traditional systems. In this context, a significant portion of the studies (12) reported indicators associated with construction project emissions, either at prototype or real scale (via simulations). Four studies did not provide empirical data but declared a reduction in environmental impacts through modern construction methods. Only one study (P53) reported variable behaviors regarding project environmental impacts, which fluctuate based on calculation methodologies and analyzed categories. This type of background has been reported mainly in China and some European countries, such as the United Kingdom and Italy, and to a lesser extent in Australia. The following is a summary of the data reported by the authors: overall percentage reduction in environmental impacts on construction projects (Figure 7), total greenhouse gas emissions (Figure 8), and emissions normalized per square meter (Figure 9). Figure 7 displays values of environmental impact reduction in housing projects, which are all based on prefabricated systems and are evaluated across categories such as embodied carbon (P45), damage to the ecosystem (P31), damage to health (P31), resource depletion (P31), global warming potential (GWP) (P46), and other unspecified categories (P63 and P51). In Figure 8, the reported data on total emissions show that for construction system T1, emissions are attributed to the manufacturing phase of a building solution in Italy. For construction system M13, located in Chile, emissions are reported at the household level, projecting a lifespan of 50 years. Lastly, for construction system P40, emissions refer to the construction of homes based on prefabricated and traditional systems from Norway. In this regard, the case studies are not directly comparable to each other because they provided data for specific categories without considering the same analysis period. Figure 8: Total emissions of industrialized and traditional projects/solutions. Figure 7: Environmental indicators of industrialized and traditional projects/solutions. In Figure 9, the summary for one of the most reported impact categories, global warming potential (GWP), ranges between 60 and 2848 [kgCO\({}_{2}\)eq/m\({}^{2}\)] for prefabricated construction (P17, P59) and between 258 and 3055 [kgCO\({}_{2}\)eq/m\({}^{2}\)] for traditional construction (P52, P59). For this same impact category, it is stated that using 50% prefabrication in projects could achieve up to a 30% reduction in emissions, as indicated by study P46. In this context, energy demand in production, transportation, and indirect emissions contributes proportions of 3%, 3%, and 94%, respectively, with the manufacturing phase being the most significant contributor to environmental impacts. Studies P17, P35, and P46 also noted that in addition to global warming, other effects such as methane generation, ozone depletion, and terrestrial acidification should be considered, as the specification or use of bio-based materials does not always equate to low environmental impact. Even though certain biological materials do not automatically guarantee reduced environmental impact, prefabrication is highlighted as being capable of reducing impacts by 5-40%. Concrete and steel, responsible for 75% of greenhouse gas (GHG) emissions, are pivotal within the industry; thus, efforts have been assessed for their optimized use, reuse, and recycling. A specific study shows a 34% reduction in embodied carbon compared to traditional homes.