- 15. April 2026
New EASI ZERo publication at CLIMA 2025: “Optimizing Building Envelope Interventions for Zero-Energy Renovations: Energy and CO2 Savings across European Member States”
We are pleased to share a new EASI ZERo publication presented at the 15th REHVA HVAC World Congress – CLIMA 2025:
Authors: Essam Elnagar, Ivan Jankovic, & Rutger Broer
This conference paper explores how innovative bio-based insulation materials can support zero-energy renovations of residential buildings across Europe, while reducing both final energy use and operational CO2-emissions.
Using an ISO 52016-aligned energy modelling framework, the study assesses the performance of different renovation strategies across European Member States. The analysis focuses on key performance indicators such as:
- final energy consumption
- CO2-emissions
- net energy use reduction
- payback time
A central concept in the paper is the use of critical R-values: The insulation levels beyond which adding more insulation leads to less than 3% additional reduction in energy use or emissions. This helps identify the point at which further insulation delivers diminishing returns.
Key findings
The study shows that integrated building envelope renovations are far more effective than isolated single measure:
Comprehensive insulation of walls, roofs, and floors delivers the most significant reductions in final energy demand, confirming the value of addressing the building envelope as a whole.. The study also shows that integrated envelope upgrades have strong potential to reduce operational CO2- emissions across a range of national contexts, underlining their relevance for Europe’s climate objectives. At the same time, the analysis identifies critical insulation thresholds, which help determine the point at which adding more insulation results in only limited additional benefits. Finally, payback times were found to vary substantially between countries, highlighting the importance of local market conditions, renovation costs, and national circumstances when designing effective renovation strategies.
Why this matters
These findings reinforce one of the core messages of the EASI ZERo project: deep, integrated renovation strategies are essential to meet Europe’s energy efficiency and climate objectives.
Rather than relying on isolated upgrades, the paper highlights the value of combining interventions across the building envelope to maximise impact. At the same time, the results underline the need for country-specific approaches, since economic performance and payback periods differ substantially across national contexts.
From research to market uptake
This publication is part of the final phase of the EASI ZERo project, where partners are working to validate product requirements and support the transition from innovation to real-world market solutions. The results contribute to a stronger evidence base for the deployment of bio-based insulation materials in zero-energy renovations across Europe.
Read the conference paper here.
We look forward to sharing more results soon and discussing the final outcomes of EASI ZERo at the project’s final conference in Brussels. Click here to sign up!