Héctor Martínez González is an industrial engineer with experience in building engineering projects, including hydraulic systems, fire protection and heating, ventilation and air-conditioning, as well as in energy efficiency and sustainability.

He joined NTT DATA in 2011, initially providing sustainability consultancy for construction projects – including LEED, BREEAM, WELL and Envision certifications – for both public and private-sector clients. He currently leads NTT DATA’s sustainability value proposition for private-sector clients, encompassing corporate sustainability, climate, nature, energy efficiency and sustainability in construction.

BUILD UP (BUP): The Energy Performance of Buildings Directive (EPBD), the EU Taxonomy and Level(s) are progressively introducing common requirements and methodologies for areas such as operational energy use, whole-life carbon, climate resilience and life-cycle assessment. How are voluntary sustainability certification schemes adapting to this evolving European framework, and to what extent can existing project documentation be reused across the different systems?

Héctor Martínez González (HMG): It has always been part of the DNA of private, voluntary sustainability standards to keep the building sector a step ahead of regulation. For a building to be recognised as sustainable under these schemes, it has traditionally had to go beyond minimum compliance in areas such as energy and water efficiency, materials, indoor environmental quality and, increasingly, carbon across the whole life cycle. As the regulatory floor rises, that role does not disappear; rather, it shifts towards helping the market anticipate new requirements, integrate them coherently and demonstrate higher levels of performance.

Life-cycle assessment (LCA) is a good example. The most established certification schemes have required or rewarded LCA for years, so many project teams already have experience defining system boundaries, collecting environmental product data and comparing design alternatives. The revised EPBD brings life-cycle global warming potential into the regulatory mainstream, while Level(s) provides a common European language for several of the same sustainability topics. In that sense, voluntary schemes have acted as a practical training ground for requirements that are now becoming more standardised at European level.

The adaptation is already taking place through successive scheme updates. Certification bodies are increasingly mapping their credits and evidence requirements against European policy frameworks, including the EU Taxonomy, and aligning terminology and calculation approaches where this adds value. However, we should not expect a perfect one-to-one correspondence: regulation, the Taxonomy, Level(s) and voluntary schemes have different purposes, scopes and thresholds. The useful objective is therefore not identical systems, but a clear translation between them so that project teams understand which evidence is equivalent, which evidence can be reused and where a specific gap analysis is still required.

In practice, the opportunity for reuse is significant. Energy models and energy performance certificate inputs, LCA studies and environmental product declarations (EPDs), climate-risk assessments, water calculations, commissioning records, materials information and indoor-environmental-quality evidence can often serve several purposes if they are prepared with sufficient traceability. The most efficient approach is to create a common project evidence base –a kind of single source of truth – from which the different regulatory and voluntary submissions can be generated. That would reduce duplication, lower transaction costs and, most importantly, allow teams to spend less time recreating documentation and more time improving the actual performance of the building.

BUP: European legislation is raising the minimum performance expected of buildings, particularly in relation to zero-emission buildings, whole-life carbon and climate resilience. Against this background, should voluntary certification schemes redefine their benchmarks and set their highest levels of achievement clearly above minimum regulatory requirements?

HMG: Yes. The credibility of voluntary standards depends largely on their ability to remain ahead of regulation. If the highest certification levels simply reproduce the legal minimum, the schemes lose much of their value as a signal of leadership. As requirements for zero-emission buildings, whole-life carbon and climate resilience become part of the regulatory baseline, the upper tiers of voluntary schemes should move further towards outcome-based performance: lower life-cycle emissions, better resilience, more circular use of materials, healthier indoor environments and stronger evidence that design intentions are achieved in operation.

At the same time, ambition must be managed carefully. Benchmarks should be reviewed periodically and raised in a transparent and predictable way, giving the market enough time to adapt and ensuring that requirements remain technically meaningful and verifiable. I also believe innovation should receive greater emphasis. Certification schemes are well placed to reward unconventional solutions, new combinations of technologies or management approaches, and project-specific responses that deliver better results than standard practice. The highest levels of certification should therefore recognise not only compliance with a demanding checklist, but also measurable performance, innovation and the capacity of a project to demonstrate what the next generation of mainstream practice could look like.

‘The highest levels of certification should therefore recognise not only compliance with a demanding checklist, but also measurable performance, innovation and the capacity of a project to demonstrate what the next generation of mainstream practice could look like’

BUP: Level(s) provides a common European framework for measuring the sustainability performance of buildings across areas such as energy, life-cycle carbon, water, materials, comfort, resilience and life-cycle costs. Could it become a shared technical language connecting European legislation with voluntary certification schemes and improving the comparability of results?

HMG: Level(s) has a challenging but very promising path ahead if it is to become a shared technical language for building sustainability in Europe. Its strongest value, in my view, is not that it should become another certification label, but that it can provide a common set of concepts, indicators and methodologies that different actors recognise. That common language can help connect regulation, public procurement, finance, corporate reporting and voluntary certification, making it easier to compare information that today is often produced using different definitions and assumptions.

Voluntary standards have, however, accumulated decades of practical experience. They have tested indicators in real projects, learned how requirements are interpreted by designers and contractors, adapted to regional differences and developed market recognition and communication value. Level(s) can benefit from that experience: it can take advantage of what has worked well in existing schemes while avoiding excessive complexity or requirements that are difficult to verify consistently. Conversely, voluntary schemes can use Level(s) as a reference point when they update their own methodologies, which would progressively increase alignment without eliminating their distinctive features.

For comparability to improve, the key issue is not only the name of the indicator but also the underlying rules: system boundaries, reference study periods, datasets, calculation assumptions and verification procedures all need to be sufficiently consistent. If that technical foundation is shared, the market can continue to support a diversity of schemes while still exchanging meaningful data. I therefore do not see the choice as being between many standards and one single framework. A more realistic model is coexistence: Level(s) can act as a common protocol layer, while voluntary certifications continue to provide market differentiation, communication, independent verification and a space for innovation. As long as those schemes remain useful and trusted, they will continue to coexist with the European framework rather than simply being replaced by it.

BUP: Voluntary certification schemes have often introduced and tested approaches – such as commissioning, life-cycle assessment, indoor air quality monitoring and efficient water management – before they became widely reflected in legislation. Can these schemes continue to serve as laboratories for innovation and provide evidence that helps shape future building regulations?

HMG: Yes, voluntary schemes can continue to act as laboratories for innovation, but I would distinguish clearly between experimentation and regulation. Certification systems can introduce new criteria relatively quickly, test them across different project types and markets, and observe whether they are technically feasible, understandable and capable of producing the intended outcomes. This flexibility is extremely valuable in areas where practice is evolving rapidly – for example, whole-life carbon, commissioning, indoor air quality, water efficiency, circularity or climate resilience.

Formal regulation must follow a different path. It has to be stable, enforceable, proportionate and applicable to a very broad market, so it cannot change at the same speed or accept the same level of uncertainty. The useful relationship is therefore a structured feedback loop: voluntary schemes can test approaches, collect evidence on costs, benefits, market acceptance and unintended consequences, and share those lessons with policymakers and standardisation bodies. Post-occupancy data and verified project results are particularly valuable because they show whether a requirement works in practice rather than only on paper. Regulation should still make its own independent assessment, but it can benefit from this accumulated evidence. In that sense, voluntary schemes can help de-risk future regulatory innovation without becoming a substitute for the public rule-making process.

‘Voluntary schemes can help de-risk future regulatory innovation without becoming a substitute for the public rule-making process’

BUP: Public regulation establishes minimum requirements for the whole market, while private certification schemes can promote higher levels of ambition, test new solutions and recognise exemplary projects. What would an effective and mutually reinforcing relationship between these two systems look like, and how could greater interoperability help prevent duplication of work?

HMG: Achieving full interoperability between voluntary schemes and regulatory requirements is probably neither realistic nor necessary, because the two systems serve different purposes. Regulation establishes a common public-interest baseline for the entire market, while voluntary certification is generally used to differentiate projects, respond to investor or occupier expectations, communicate performance and encourage leadership. In addition, voluntary schemes may be used by international stakeholders whose portfolios extend well beyond the EU, so they need a degree of continuity and comparability across different regulatory environments.

That said, a high level of technical interoperability is both possible and desirable. The objective should be to define a common core of project data and evidence that can be reused across systems. Energy-performance calculations, life-cycle assessments and EPDs, climate-risk studies, water data, commissioning records, materials information and indoor-environmental-quality measurements should not have to be recreated simply because the same project is being assessed under several frameworks. Where methodologies are aligned, we should be able to ‘measure once and report many times’, with each system applying its own thresholds or additional requirements to the same underlying evidence.

To make this work, clear mapping documents, common definitions, digital data structures and robust traceability are essential. Project teams need to know which regulatory evidence is accepted by a certification scheme, which certification outputs can support Taxonomy or Level(s) reporting, and where additional verification is required. This would turn interoperability into a practical reduction of effort rather than a theoretical alignment exercise. Ultimately, I see regulation and voluntary certification as complementary: public rules set the floor and protect the general interest, while private schemes can raise ambition, recognise exemplary performance and test new solutions. The better the interface between them, the lower the administrative burden and the more resources can be directed towards improving buildings themselves.