This article explores the shift towards human-centred buildings, highlighting the role of indoor environmental quality, occupant behaviour and passive solutions in bridging the gap between the policy ambition and performance in use.
(Note: Opinions in the articles are of the authors only and do not necessarily reflect the opinion of the European Union)
The European debate on building performance has long been dominated by a technology-driven vision of smart buildings, centred on automation, controls, sensors and digital optimisation. These developments remain important for improving the operational efficiency of buildings and integrating them into more flexible and decarbonised energy systems. However, they do not automatically guarantee that buildings are healthy, comfortable or effective in real use. A building may be technically advanced and still perform poorly for its occupants if indoor air quality (IAQ) is inadequate, overheating is not addressed, systems are difficult to operate, or user needs are treated as secondary to compliance and automation.
This disconnection between technical capability and actual user experience is increasingly visible in Europe, where buildings are expected not only to reduce emissions but also to actively support health, wellbeing and resilience in everyday use.
Recent evidence shows that indoor environmental quality (IEQ), particularly air quality and thermal conditions, has measurable effects on health, cognitive capacity and productivity, while inadequate indoor environments are consistently linked to discomfort and reduced wellbeing (Grassie et al., 2025; Niza et al., 2024). At the same time, empirical studies of buildings in operation point to a recurring mismatch between compliance-based design expectations and actual indoor conditions, especially in highly energy-efficient buildings where overheating and insufficient ventilation are frequently observed (Wu et al., 2023; Carletti et al., 2024).
In response, building performance is increasingly discussed in terms of conditions observed during operation rather than values assumed at the design stage. This reorientation places IEQ at the centre of performance assessment, alongside energy use, and highlights the influence of occupants, whose interactions with building systems (through window operation, shading or control adjustments) can significantly alter indoor conditions in ways that are not captured by standard modelling approaches (Guerra-Santin et al., 2024).
Rather than treating occupants as passive users, this perspective recognises them as active participants in building performance. It also draws attention to the importance of usability, awareness and everyday practices in determining whether buildings perform as intended.
This shift in perspective is closely linked to the evolution of IEQ within European standards and policy frameworks. Traditionally, technical standards such as EN 15251 and its successor EN 16798-1 have defined indoor environmental categories and input parameters primarily to support energy performance calculations. As a result, the emphasis has been placed on thermal comfort, lighting, and ventilation rates, which are often used as proxies for IAQ, while other dimensions, such as acoustic comfort, are not explicitly integrated within the same framework, as they do not directly influence energy use.
In practice, this has meant that IEQ has often been treated as a set of standardised input assumptions (such as fixed ventilation rates, temperature setpoints, and occupancy profiles) rather than as a set of performance outcomes reflecting how buildings actually function in use and how occupants experience indoor environments. (Perera et al., 2025; Seminara et al., 2022).
This has contributed to a well-documented performance gap, whereby buildings that satisfy design-stage requirements frequently fail to deliver adequate indoor environmental conditions in use, due in part to simplified modelling assumptions and the limited integration of post-occupancy evaluation (Rohde et al., 2021; Elsayed et al., 2023; Jain et al., 2021).
Recent research and policy developments increasingly challenge this approach by emphasising the need to assess indoor conditions under real operating scenarios. This includes greater attention to overheating risk, adaptive thermal comfort and the effectiveness of ventilation strategies, particularly in the context of climate change. Studies on thermal resilience show that buildings designed primarily for energy efficiency may be vulnerable to prolonged heat events unless passive and adaptive measures are incorporated (Amaripadath et al., 2024). Similarly, reviews of IEQ and energy codes highlight the need to align performance metrics with health and comfort outcomes rather than relying solely on calculated compliance indicators (Perera et al., 2025).
The revised Energy Performance of Buildings Directive (EPBD) (EU) 2024/1275 marks a significant step in this evolution. It more clearly embeds IEQ within the logic of building energy performance. The directive defines IEQ as the set of indoor conditions affecting the health and wellbeing of occupants, including temperature, humidity, ventilation and the presence of pollutants, and introduces provisions to ensure that energy performance measures do not adversely affect these conditions. It also strengthens requirements related to ventilation and the inspection of technical building systems, signalling a more systematic consideration of indoor environments within regulatory frameworks.
This policy direction is further elaborated in the European Commission’s Staff Working Document on supporting indoor air quality (European Commission, 2024), which highlights that current regulatory approaches have often relied on ventilation rates and proxy indicators rather than direct assessment of indoor pollutants and exposure. The document emphasises the need to move towards more comprehensive and measurable approaches to IAQ, including better monitoring, clearer performance indicators and improved integration of health considerations into building policies. It also underlines that energy renovation measures, if not properly designed and implemented, can negatively affect indoor air quality, for example by reducing air exchange rates or introducing pollutant sources.
At the same time, implementation remains largely within the competence of Member States. While the European Union sets the overarching legislative framework and objectives, national and regional authorities are responsible for translating these requirements into building codes, ventilation regulations, inspection schemes and renovation programmes. This leads to significant variation across Europe in how IEQ is addressed in practice.
Understanding how this policy's ambitions translate into practice requires insights from both standards development and real-world evidence. Recent work by Lagoudas et al. (2026) highlights that, despite the integration of IEQ into the EPBD, its implementation risks becoming fragmented, as Member States must define indicators, thresholds and verification methods themselves. Many countries still lack comprehensive IAQ standards, and existing approaches often rely on proxy indicators such as ventilation rates rather than direct pollutant measurement.
Inspection regimes also differ widely, and standards remain only partially adapted to modern systems such as demand-controlled ventilation. While the revised EPBD strengthens inspection requirements and points towards performance-based verification, its effectiveness will depend on consistent national implementation, particularly regarding monitoring, enforcement and alignment with real operating conditions.
This Topic of the Month is enriched by an expert talk with Professor Bjarne Olesen (Technical University of Denmark, DTU), whose work has been instrumental in shaping international standards for thermal comfort, ventilation and energy performance. His perspective highlights key challenges in current approaches, including the gap between standard requirements and their implementation in practice, the need to better account for occupant diversity, and the importance of aligning control strategies with real user needs. He also reflects on the role of the EPBD in advancing indoor environmental quality, while pointing to the need for stronger alignment and uptake of existing standards such as EN 16798 across Member States.
From a regulatory and operational perspective, this transition towards performance-based approaches is explored in the technical article contribution by Valérie Leprince (Cerema), which examines how the revised EPBD can support a shift from prescriptive ventilation requirements towards the assessment of actual indoor air quality outcomes across the building life cycle. Her analysis highlights that current compliance-based approaches (largely based on fixed airflow rates) are insufficient to reflect real conditions of use, particularly in buildings with demand-controlled or hybrid ventilation systems. It therefore underlines the need for national regulations, standards and professional practices to evolve in parallel, embedding performance-based IAQ criteria at design, commissioning, inspection and operation stages, in order to ensure that policy objectives translate into measurable and verifiable outcomes in practice.
Complementing this, Corinne Mandin (University of Rennes) brings evidence from field studies and large-scale monitoring campaigns, demonstrating that indoor environmental quality in real buildings (particularly in sensitive environments such as schools) often remains inadequate. Her work underlines both the health implications of poor indoor air quality and the current gap between regulatory frameworks and actual indoor conditions, while emphasising the opportunity provided by the EPBD to more effectively integrate IEQ into building policy and practice.
This Topic of the Month also draws on insights from Professor Wouter van Marken Lichtenbelt (Maastricht University), whose work in human thermophysiology provides a complementary perspective on indoor environments. His research demonstrates that exposure to more dynamic indoor temperatures can support metabolic health, enhance resilience and allow for wider comfort ranges, thereby potentially reducing energy demand.
This challenges the long-standing assumption that stable, uniform indoor conditions are inherently optimal, pointing instead towards adaptive and human-centred approaches. Passive and climate-responsive design strategies are receiving renewed attention as essential components of building performance. A recent review by Toroxel and Silva (2024) demonstrates that measures such as solar shading, thermal mass, natural and night-time ventilation, and climate-adapted building form can significantly reduce overheating risk while improving indoor comfort without increasing energy demand. These approaches offer robust, low-energy solutions that are particularly relevant in the context of climate change and increasing temperature extremes.
Digital technologies, in this context, are not displaced but reassessed. Monitoring systems, sensors and automated controls are increasingly valued for their capacity to provide feedback on actual indoor conditions and to support adaptive operation, rather than simply optimising predefined energy targets (Alongi et al., 2025). Their effectiveness depends less on technological sophistication alone and more on how they are integrated with building design, operation and user interaction. Importantly, achieving these outcomes requires not only technical solutions but also stronger user engagement, awareness and capacity-building across the sector. Education, skills development and co-creation processes are therefore essential to ensure that buildings are not only well designed but also well understood, operated and adapted over time.
This shift towards adaptive and user-centred comfort is also reflected in emerging implementation approaches, such as the EffiComfort initiative, where comfort is treated as a dynamic, user-driven outcome rather than a fixed technical parameter. EffiComfort, supported under the European Urban Initiative, explores new operational and business models that integrate energy efficiency and occupant comfort as a single service. EffiComfort reframes comfort as a managed outcome, shaped by user experience, building operation and continuous feedback. This approach is further illustrated in the Portico urban story ‘Co-creating Comfort: How Ljubljana Is Reframing Building Performance Around People’, which highlights how local implementation can bridge policy ambitions with real-life building use.
Many of the benefits associated with human-centred buildings, such as improved health, reduced absenteeism, enhanced learning environments and increased productivity, are not yet systematically reflected in investment decisions or cost–benefit analyses. As a result, investments in ventilation quality, passive design, user engagement or building operation are often undervalued, despite being critical for achieving real performance outcomes.
Simona D’Oca (JLL) explores how the real estate sector is evolving towards data-driven approaches that redefine building value by integrating operational performance, occupant experience and sustainability objectives. Her contribution highlights how smart building ecosystems, combining Internet of Things (IoT) technologies, digital solutions and strategic asset management, can generate measurable value while supporting human-centred outcomes.
This perspective is complemented by the contribution of Loes Visser (DataBuilt), who emphasises the need to bridge the persistent gap between calculated energy performance and real indoor environmental conditions through the integrated use of operational data. By linking energy use, system behaviour and occupant experience, her work illustrates how buildings can move from reactive management towards continuous, performance-based optimisation in use.
Beyond research and standards, these approaches are increasingly being tested and implemented through EU-funded initiatives:
Horizon Europe projects such as TwinAIR, KHealthInAir, together with initiatives like Inchildhealth, are contributing to a stronger evidence base on the links between indoor environmental quality, exposure and health, particularly in vulnerable environments such as schools and residential buildings. These projects move beyond traditional compliance approaches by focusing on real conditions of use, occupant exposure and health-related outcomes, thereby directly informing the evolving policy context under the EPBD.
Complementing these approaches, the LIFE Clean Energy Transition project BREEZE is working to embed comfort, health and user-centred performance into building renovation practices, addressing both technical and behavioural dimensions. Earlier initiatives such as MOBISTYLE have already demonstrated the potential of behavioural interventions and user feedback to influence both energy consumption and indoor environmental conditions, while the Marie Skłodowska-Curie Actions such as MuSIC and DyLiOpt contribute advanced research on multi-sensory comfort, adaptive environments and the interaction between lighting, health and performance.
Together, these projects illustrate a clear shift from fragmented, technology-driven solutions towards integrated approaches that combine data, behaviour, health and building operation. They also highlight the importance of connecting EU-level innovation with national and local implementation contexts. In this respect, frameworks such as Level(s) and tools like the CRREM play a key role in translating these insights into assessment methodologies and investment strategies, supporting a more holistic evaluation of building performance that includes carbon, comfort and user wellbeing.
Building performance is increasingly understood as the ability of buildings to deliver healthy, comfortable and resilient indoor environments under real conditions of use. This requires moving beyond compliance-based approaches towards performance in operation, where indoor environmental quality, energy use and occupant interaction are treated as interdependent dimensions. It also calls for stronger integration of passive design, adaptive strategies and user engagement, supported by more effective use of data to monitor and manage buildings over time.
Rather than replacing smart technologies, this shift places them within a broader framework where their role is to support rather than define, building performance. Achieving this transition will depend on closer alignment between EU policy, national implementation, standards and practice, as well as on better recognising the value of health and wellbeing in decision-making. Ultimately, the success of Europe’s building transformation will be measured not only by energy and carbon indicators, but by how effectively buildings respond to the needs, diversity and everyday experiences of their occupants.
At its core, this transformation raises a fundamental question for building professionals: how can we design, operate and regulate buildings that not only perform efficiently on paper but truly work for people in everyday life? As shown in this Topic of the Month, this question requires continued collaboration across disciplines, stronger engagement with users and a willingness to rethink long-standing assumptions about comfort, performance and value.
BUILD UP invites its community to contribute to this transition by sharing knowledge, practices and insights that help turn human-centred performance from ambition into reality.
