Abstract
Plans to decarbonise residential construction in many countries focus mainly on reducing the operational energy of dwellings and associated greenhouse gas (GHG) emissions, rather than the full life-cycle emissions of construction. Although there is a growing body of data that measures the embodied carbon (EC) of different housing types, existing studies have mainly assessed materials within the building envelope. Where siteworks and infrastructure are included, there is often a lack of clarity regarding the physical scope of site boundaries due to the various methodologies used, making it difficult to compare results across studies. This gap is addressed by research underpinning a new framework that provides precise definitions of the physical scope of EC assessment at a range of scales from building to neighbourhood, allowing siteworks to be included in the EC calculations of new developments. A case study housing development in Ireland illustrates the framework. The results show that siteworks comprising hard landscaping and infrastructure add an additional 32% to the total EC for life-cycle stages A1–A5 of low-rise housing typologies, demonstrating the importance of the framework. By integrating siteworks into life-cycle assessment (LCA) calculations, the research highlights the relationships between building typology, residential density and EC emissions.
POLICY RELEVANCE
Guidance is provided for urban planners, developers and construction professionals focused on designing low carbon districts. While some countries have established EC targets for various housing types, there remains a critical lack of guidance on GHG emissions linked to constructing the broader urban environment and its supporting infrastructure. This research addresses that gap by presenting a framework that breaks down urban form into distinct elements, enabling separate assessment of their EC impacts. Using a greenfield development as a case study, the findings highlight the substantial contribution of siteworks to upfront emissions. Moreover, the framework offers a framework for comparing developments involving existing structures and infill projects integrated into established urban landscapes and infrastructures, thereby supporting policies promoting compact growth and densification within current urban footprints.