A Simple Blueprint for Climate and Cost Savings in Building Renovation

By Antonia Egli and Radhika Deorukhkar (Dublin City University) and edited by Vasilis Apostolopoulos, Ioannis Mamounakis, Andreas Seitaridis, Nikolas Tagkoulis, Dimitrios-Sotirios Kourkoumpas, Petros Iliadis, Komninos Angelakoglou, and Nikolaos Nikolopoulos

What is the biggest problem with Europe’s old buildings?

Imagine a technology that slashes your carbon footprint while simultaneously saving you hundreds of thousands of Euros. With the climate crisis deepening, buildings have become a key part of the problem, globally responsible for nearly 40% of total carbon dioxide emissions. In the European Union, a staggering 75% of the existing building stock is considered energy inefficient. But these old, energy-hungry structures present both a challenge and an opportunity. New research, focused on a multi-family building in Athens, Greece, demonstrates how a “deep renovation” approach can achieve ambitious climate goals while delivering remarkable financial returns for property owners. The study “Αn integrated life cycle assessment and life cycle costing approach towards sustainable building renovation via a dynamic online tool” provides a powerful, data-driven business case for green building retrofitting.

What did the research explore and why is it important?

The study directly addresses the goals of the European Green Deal and the “Renovation Wave,” which calls for the accelerated retrofitting of buildings towards nearly zero energy standards. Researchers compared the current energy performance of an old social multi-family housing building in the municipality of Moschato-Tavros, in Athens, Greece, with a proposed deep energy renovation package designed to meet the rigorous Passive House standard. 

The analysis was powered by a dynamic online tool called VERIFY (Virtual integrated platform on Life cycle Analysis). This tool integrates two critical evaluation methods: Life Cycle Assessment (LCA), which measures environmental impact, and Life Cycle Costing (LCC), which tracks all costs over the project’s lifespan.

Crucially, the VERIFY platform moves beyond static analysis by incorporating dynamic data, such as real-time consumption and future changes to the energy grid mix. The renovation scenario included radical building envelope changes, new high-efficiency heat pump systems, and the integration of on-site solar power. The comprehensive analysis covered an operational lifespan of 25 years.

What are the biggest environmental and financial benefits?

The life cycle analysis of the Greek building renovation revealed that a comprehensive approach to retrofitting delivers rapid and significant environmental and economic benefits.

• Near-Total Carbon Reduction: The renovation scenario achieved an outstanding 95% reduction in CO2_eq emissions over the 25-year lifespan compared to the old building’s performance. This proves that existing structures can be brought in line with +nearly zero-energy targets.
• Massive Energy Savings: The building’s overall primary energy needs were reduced by 91%. Operational energy consumption plummeted from 578.62 kWh/y/m² to just 56.85 kWh/y/m², comparable to some of the most efficient new buildings in Europe.
• Quick Financial Payback: Deep retrofitting proved highly cost-effective, with the total investment costs paid back in an attractive timeframe of 3 years and 6 months. The building began to provide net monetary savings from the third year of operation.
• Half a Million Euro in Savings: Over the 25-year operational lifespan, the implemented renovation actions can lead to total cost savings of over 515,000 €.
• Solar Power Pays for Itself Quickly: The Photovoltaic (PV) systems installed to generate clean electricity were shown to have a very rapid energy payback time of just 3 years and 3 months, demonstrating the efficiency of incorporating renewable energy sources.

What is the social impact?

Through the VERIFY lifecycle approach and the application of the Passive House standard, the project significantly reduced energy needs and carbon footprint, effectively tackling energy poverty and improving the comfort and quality of life of the low-income households living in the building. Supported by RINNO as its Greek demo and realised as the Tavros Project, this deep renovation also received the New European Bauhaus Prize 2025 for “Prioritising the places and people that need it the most”. Together, this research and the real-world implementation outcomes of this deep energy retrofit are proof that the energy transition can be fair, practical, and achievable even in the most challenging urban contexts.

Why does this matter for policy and industry?

These findings offer a compelling, data-driven template for property owners, investors, and policymakers across the European Union. With around 75% of the EU’s building stock being energy inefficient, this deep renovation approach provides a clear and proven pathway to achieving the ambitious decarbonisation targets set out by the European Green Deal.

For industry professionals and engineers, the innovative technology behind the study, the VERIFY tool, is a game-changer. Historically, building performance analysis has relied on static averages, which can lead to inaccuracies and unreliable investment projections. VERIFY’s capacity for Dynamic Life Cycle Assessment means that performance is assessed using real-time variables like updates in the local energy grid mix, precise temperature variations, and actual building occupancy profiles. This gives investors and project managers a far more accurate and reliable picture of the financial and environmental risk, supporting optimal investment decision-making. 

Consider the application in local policy: A municipality in Athens, or any large European city, could use this data to mandate minimum performance standards for renovations. The knowledge that a deep retrofit can reduce emissions by 95% and save a property over half a million euros in the long term allows policymakers to justify grants and incentivise private investment. This model can be scaled up from a single multi-family block to entire housing estates, providing a replicable blueprint for Europe’s urgent “Renovation Wave.” By proving that aggressive environmental action is also a financially smart long-term investment, the research provides the necessary data to drive a fundamental market transformation.

What is the future of sustainable buildings?

The research clearly shows that renovating old, inefficient buildings to the highest energy standards is not just an environmental imperative; it is a profound financial opportunity. Deep retrofits, combined with dynamic analysis tools like VERIFY, offer a robust and economically sound solution to tackling the building sector’s enormous energy consumption. The ambitious goal of a Nearly Zero Energy Building is within tangible reach for almost any existing structure. The next key step is making this dynamic, data-driven approach the universal standard for every renovation project worldwide, ensuring that every retrofitted building contributes to a sustainable future.

Reference:

Apostolopoulos, V., Mamounakis, I., Seitaridis, A., Tagkoulis, N., Kourkoumpas, D.-S., Iliadis, P., Angelakoglou, K. and Nikolopoulos, N. (2023) ‘An integrated life cycle assessment and life cycle costing approach towards sustainable building renovation via a dynamic online tool’, Applied Energy, 334, 120649. https://doi.org/10.1016/j.apenergy.2023.120710