Design Strategies for Achieving Circular Economy in Buildings

Zahra Jahangiri and Kartikeya Rajput

Reducing embodied carbon in the built environment requires practical methods for reducing material extraction, waste and carbon impacts. Circular economy provides a framework for keeping materials and building components in use at their highest value for as long as possible; however, guidance for translating circular economy principles into design decisions remains fragmented. This paper aims to address this by identifying and categorising practical solutions for achieving circularity in buildings through a comprehensive literature review. Selected building elements are assessed using One Click LCA’s Building Circularity Tool. To connect theory with practice, hands-on construction-site experience at the ‘New Story Garden’ in London is examined as a case study, assessing the application of the strategies identified in the literature review and revealing practical barriers and opportunities. The paper therefore proposes a clearer method linking circular economy principles, building layers, technical strategies and their circularity rationale, while identifying practical factors affecting their implementation.

Keywords: circular economy, waste, reclaimed materials, building layers

Balancing Embodied and Operational Carbon through Shading Design in Vertical Extension Retrofits

Zahra Ghenaat

The construction sector must reduce both embodied and operational carbon emissions to meet net zero targets. While external shading can lower cooling demand, it also introduces embodied carbon through additional material use. This paper investigates whether operational carbon savings from façade shading can offset its embodied carbon over a 60-year building life. The Crowndale Centre in London is used as a case study of a three-storey vertical extension. Existing aluminium roofing is repurposed as external shading. Solar radiation analysis and dynamic thermal simulations using TAS are combined with life cycle assessment in OneClick LCA to evaluate operational and embodied carbon across different shading densities and material scenarios. Results show that shading reduces operational carbon; however, the embodied carbon of primary aluminium outweighs this benefit. Recycled and reclaimed aluminium achieved net carbon reductions over 60 years, with reclaimed aluminium providing the greatest whole-life carbon benefit.  

Keywords: façade shading, operational carbon, embodied carbon, reclaimed aluminium, vertical extension 

How future decarbonisation pathways affect the life-cycle carbon footprint of rooftop PVs: A UK scenario analysis

Shufa Ansari

Rooftop photovoltaic (PV) systems are central to UK residential retrofit policy, yet conventional whole life carbon assessments (WLCAs) apply static, present-day grid and manufacturing factors across multi-decade horizons, risking overstated long-term benefit as the grid itself decarbonises. This study quantifies how future UK grid- and manufacturing-decarbonisation pathways affect the 60-year carbon footprint and payback of a 3.03kWp retrofit PV system on a UK dwelling, modelled in IESVE and an annual Excel model following EN 15978/RICS Whole Life Carbon Assessment guidance (modules A1-A5, B4, B6, C1-C4), supplemented by an EN 15804-compliant generic inventory. A static baseline is compared against three NESO Future Energy Scenarios pathways, excluding BECCS-attributed removals. The static case achieved payback in year 8 (net benefit: 19,513 kgCO2e) whereas no dynamic pathway achieved payback within 60 years, since avoided emissions fell faster (81-97%) than embodied carbon (47-61%). Findings challenge static WLCA practice for grid-displacing technologies.

Keywords: Whole-life carbon assessment, dynamic LCA, photovoltaic systems, grid decarbonisation and carbon payback