Integrated Life Cycle Assessment of Residential Retrofit Strategies: Balancing Operational and Embodied Carbon, Lessons from an Irish Housing Case Study

Thomas Nolan, Afshin Saeedian, Paria Taherpour and Reihaneh Aghamolaei ()
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Thomas Nolan: Faculty of Engineering and Computing, School of Mechanical & Manufacturing Engineering, Dublin City University, D09 DD7R Dublin, Ireland
Afshin Saeedian: Faculty of Engineering and Computing, School of Mechanical & Manufacturing Engineering, Dublin City University, D09 DD7R Dublin, Ireland
Paria Taherpour: Faculty of Architecture and Urbanism Engineering, Tabriz Islamic Art University, Tabriz 51368, Iran
Reihaneh Aghamolaei: Faculty of Engineering and Computing, School of Mechanical & Manufacturing Engineering, Dublin City University, D09 DD7R Dublin, Ireland

Sustainability, 2025, vol. 17, issue 18, 1-22

Abstract: The residential building sector is a major contributor to global energy consumption and carbon emissions, making retrofit strategies essential for meeting climate targets. While many studies focus on reducing operational energy, few comprehensively evaluate the trade-offs between operational savings and the embodied carbon introduced by retrofit measures. This study addresses this gap by developing an integrated, novel scenario-based assessment framework that combines dynamic energy simulation and life cycle assessment (LCA) to quantify whole life carbon impacts. Applied to representative Irish housing typologies, the framework evaluates thirty retrofit scenarios across three intervention levels: original fabric, shallow retrofit, and deep retrofit incorporating multiple HVAC technologies and envelope upgrades. Results reveal that while deep retrofits deliver up to 80.2% operational carbon reductions, they also carry the highest embodied emissions. In contrast, shallow retrofits with high-efficiency air-source heat pumps offer near-comparable energy savings with significantly lower embodied impacts. Comparative analysis confirms that reducing heating setpoints has a greater effect on energy demand than increasing system efficiency, especially in low-performance buildings. Over a 25-year lifespan, shallow retrofits outperform deep retrofits in overall carbon efficiency, achieving up to 76% total emissions reduction versus 74% for deep scenarios. Also, as buildings approach near-zero energy standards, the embodied carbon share increases, highlighting the importance of LCA in design decision-making. This study provides a scalable, evidence-based methodology for evaluating retrofit options and offers practical guidance to engineers, researchers, and policymakers aiming to maximize carbon savings across residential building stocks.

Keywords: life cycle assessment; energy retrofit; embodied carbon; operational energy; residential buildings (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
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