Net Zero Carbon Renovation Europe: Drivers of Low-Carbon Renovation

Achieving carbon neutrality cannot rely on new buildings alone. As Europe accelerates efforts to meet energy targets, a new report focusing on the renovation of existing buildings seeks to galvanise public and private stakeholders across Europe into decarbonising the built environment.

The Net Zero Carbon Renovation Europe programme, led by Alliance HQE-GBC, AIA Environnement and Deerns, aims to assess and promote the adoption of low-carbon objectives and strategies in renovation projects across Europe.

How does building location affect decarbonisation?

The programme highlights the issues which make it currently difficult to compare buildings in a meaningful and efficient way.

“The goal is to secure a clear understanding of the main differences between countries in the methodology, reference thresholds, regulations, data availability and tools available to support large-scale deployment of net zero carbon (NZC) renovation strategies,” says Ana Cunha, Strategic Sustainability Advisor, Deerns.

The report is based on life-cycle analysis (LCA) in four pilot countries: France, Spain, Italy and the Netherlands.

Part of the EU-financed BuildingLife project and supported by the World Green Building Council, the six main objectives are to:

• Identify how the carbon impact of buildings differ between countries due to regulatory maturity, availability of data and tools.
• Assess how local parameters influence the life-cycle carbon footprint of renovations e.g. energy mix, climate, construction methods and product emission factors.
• Support implementation of a coordinated European approach for whole-life carbon (WLC) assessment in renovation, highlighting key differences still to be resolved.
• Promote the use of Carbon Return Time (CRT) as a key indicator of environmental performance for renovations across Europe indicating the relevance of a renovation.
• Identify key drivers influencing local carbon footprint and carbon return times to help stakeholders define strategic renovation plans.
• Inform and guide through developing economic models and policies on how to accelerate low-carbon renovations across Europe.

Using life-cycle analysis to shape renovation strategy

Developing a carbon strategy for an international asset portfolio is complex. Carbon-wise, comparing an international portfolio of assets is even more complex. The NZC Renovation report and project is grounded in understanding the availability of regulations, data, and tools for assessing the whole-life carbon consideration of buildings. The study highlights:

• Availability and use of LCA methods, regulations, and carbon thresholds
  • Certifications and systems that support LCA in each country to drive carbon-oriented strategies
  • Availability of Environmental Product Declarations (EPD) databases and LCA calculation tools for each country, whether private or public
• Scope of calculation – parts and systems of the building included in the LCA calculation
• LCA standards and indicators
• Variations between countries in life stages and scope of LCA calculations.

The investigation is designed to illustrate the variation in LCA when applied to seven types of buildings, in four European capital cities – Paris, Amsterdam, Madrid and Rome. Factors assessed:

• Embodied carbon (related to materials and construction)
• Operational carbon (related to building operation)
• Carbon Return Time (CRT), i.e. the time needed to offset emissions increment associated with the renovation and the operational energy improvement.

Local production and supply of materials is accounted for through national energy emission factors and the carbon coefficients of building materials in each country.

Contrasting results that provide valuable practical insights

As a result, sustainability certifications (HQE, LEED, BREEAM, VERDE) are proving to be essential vehicles for pushing market adoption of Carbon-related strategies and Whole Life Carbon and considerations.

Carbon payback time is a highly relevant key performance indicator for Europe: it varies from six to more than 35 years depending on the type of building and the countries considered. It can double when comparing the same building in different countries. This reinforces importance of strategising the relevance of certain renovations.

Another finding was that controlling cooling is a strategic low-carbon challenge. With rising temperatures and more frequent heatwaves, demand for air conditioning is increasing. In countries where the electricity mix remains carbon-intensive, this increase can offset some of the gains achieved through renovation. Cooling-related consumption is indeed a major factor in Italy and Spain, particularly for offices. This requires accurate modelling, passive strategies, low-carbon cooling systems.

Next steps – EU NZC Roadmap; Activation

Phase 1 of the Net Zero Carbon Renovation project consisted of:

• Identifying methodological disparities between countries (regulatory maturity, availability of data and tools).
• Estimating, in order of magnitude, variations in the carbon footprint of renovations depending on national contexts (energy mix, climate, data on main construction products).

Phases 2 and 3 will aim to:

• Expand the scope of LCA by incorporating new variables (construction techniques, materials, uses), which will improve understanding of the main drivers of carbon impact by country
• Develop a European roadmap for Net Zero Carbon accompanied by concrete solutions and policy recommendations
• Strengthen stakeholder engagement, education and awareness in the building sector at continental level.

Renovation holds the key to meeting Europe’s net zero ambitions. The NZC Renovation project is helping to broaden understanding and guide stakeholders through the process so that they can harness the full potential of their portfolios.