International DGNB multiple certification across national borders with DELTA

A new standard for scalable sustainability in portfolios

Vienna — Sustainability in real estate portfolios today requires more than individual certificates. International operators face the challenge of harmonizing different regulatory frameworks, ESG requirements, and market standards while maintaining consistent quality and economic efficiency.

A new benchmark is now being set with the first international DGNB multiple certification across several countries. An internationally active trading company, HORNBACH, is pursuing this path together with DELTA as its auditing partner.

This is the first time that a structured certification system for similar buildings has been created across national borders – in Austria, Czechia, Slovakia, Serbia, and Romania.

Image credit: © DGNB

Systematic approach instead of individual project logic

The DGNB multiple certification is based on a two-stage approach:

Basic certificate

• One-time definition of a reference project (“worst-case approach”)
• Definition of all transferable sustainability criteria
• Scalability to similar buildings

Project-specific certificate

• Addition of location-specific features
• Assessment of country-specific deviations
• Ensuring regulatory compliance

This systematic approach reduces audit costs, creates consistent quality standards, and enables internationally comparable ESG documentation.

Image: Sustainability strategy – market planning © HORNBACH

Strategic added value for portfolio operators

International multiple certifications offer substantial advantages, especially for branch-structured real estate portfolios:

• Significantly shorter certification processes for follow-up projects
• Standardized sustainability criteria across countries
• Increased transparency for investors and financial institutions
• Reliable basis for taxonomy compliance
• Reusable documentation and process structures

The result is a robust, scalable sustainability system that combines economic efficiency with environmental responsibility.

Image (from left to right): Steffen Wiegerling (Certification), Michelle Hechtmann (Certification), and Lukas Gerstle (Planning), HORNBACH

Effectively establishing sustainability across borders

For DELTA, supporting this international multiple certification process means much more than just the technical handling of an audit process.

“For me, helping to shape the international multi-certification process means effectively anchoring sustainability standards across national borders. After all, issues such as decarbonization, building ecology, and resource conservation are global challenges that require joint action.”

Marion Wallner, Consultant, DELTA Group

Especially in the context of increasing ESG regulation, it is clear that sustainability needs a systematic approach. Individual measures are not enough—structural integration into processes, Planning, and portfolio strategy is crucial.

Image (from left to right): Marc Höhne (Managing Director) & Marion Wallner (Consultant & Speaker at the DGNB Annual Congress on March 5, 2026), DELTA

Technical exchange at the DGNB Annual Congress

The international multiple certification will be presented and discussed by Hornbach and DELTA at the upcoming DGNB Online Annual Congress on March 5 at 3:15 p.m. The joint presentation will highlight the process structure, “low-hanging fruits,” and key challenges in cross-border implementation. The focus will be on the question of how sustainability standards can be implemented in a scalable, auditable, and economically viable manner.

To register: https://event.dgnb.de/jahreskongress/2026/event.php?pg=profile

Pioneering role in the international DGNB context

This international multiple certification establishes a model that makes sustainability measurable, comparable, and controllable across portfolios. It combines technical excellence with strategic ESG integration and creates a robust foundation for sustainable growth in the international real estate environment.