Developing a methodology with a tool for calculating and reducing the upfront carbon emissions of buildings: Ireland as a case study

Upfront carbon emissions of buildings encompass all greenhouse gas emissions linked to building materials extraction, manufacturing, transportation, and installation processes. Many countries face barriers in calculating and reducing the upfront carbon emissions of buildings during the design stage due to unreliable materials embodied carbon (EC) data, inconsistent methods, and tool complexity. Therefore, the current study aims to develop a national adaptable methodology with a simple tool for calculating and reducing buildings’ upfront carbon emissions based on a reliable regional EC dataset. To validate the developed methodology and tool, a group of architecture firms in Ireland used it to calculate and reduce the upfront carbon emissions of their projects. Fourteen buildings representing six typologies were evaluated, and on average, the results were 436 and 648 kgCO₂e/m² for residential and non-residential buildings, respectively. The calculation method and tool have been validated since the upfront carbon emissions values align with the averages of buildings in Europe. The reduction methodology was developed using the materials’ substitution strategy to replace in-situ concrete, steel, insulation, and window frames with lower-EC alternatives. The substitutions reduced the upfront carbon emissions of the residential and non-residential case studies by 21% and 23.8% on average, achieving the Irish government's 2030 Climate Action Plan. The future development of the reduction methodology can go further by considering more key materials.