Building conversations up with... Jarek Kurnitski, Full Professor at Tallinn University of Technology and Adjunct Professor at Aalto University.
Professor Jarek Kurnitski is one of Europe’s leading experts in energy performance of buildings, known for bridging scientific research, standardisation, and policy implementation. He leads the Nearly Zero Energy Buildings (NZEB) research group at Aalto University, and is a Full Professor and Head of the Department of Civil Engineering and Architecture at Tallinn University of Technology.
He also leads Estonia’s Centre of Excellence in Energy Efficiency ENER (2024–2030), and previously coordinated the Energy Programme of SITRA, Finland’s Innovation Fund. He has recently been appointed Vice-President of REHVA (2025–2028), in addition to his long-standing role as Chairperson of the Technology and Research Committee.
Professor Kurnitski has played a pivotal role in developing building stock calculation frameworks and national energy performance regulations in both Estonia and Finland. His work has shaped technical definitions and system boundaries for NZEB, and he has been an active contributor to CEN standardisation (notably TCs 156, 89, 228, and 371) as well as co-author of key WHO and REHVA guidance on indoor environmental quality (IEQ) and healthy, low-energy buildings.
BUILD UP (BUP): What are the most promising ways countries can leverage building stock data and National Building Renovation Plans (NBRPs) to ensure data-driven progressive renovation strategies and Minimum Energy Performance Standards (MEPS) implementation?
Jarek Kurnitski (JK): To design effective progressive renovation strategies and implement MEPS successfully, countries need robust, integrated building stock data systems. This means combining national building registries with energy statistics to create a comprehensive, bottom-up view of how the building stock evolves. For example, Estonia operates a national building registry that records detailed data for each building, including floor area, typology, and, where available, Energy Performance Certificates (EPCs). Countries without complete EPC coverage can still adopt this approach by using reference building archetypes combined with available energy data to estimate performance baselines and project impacts. This enables authorities to distinguish between detached houses, multifamily apartments, and non-residential buildings, allowing much more precise modelling.
By linking this registry with national energy consumption statistics, covering electricity, district heating, and fuels for residential and non-residential buildings, it is possible to validate the building stock model. In this way, Estonia can simulate the development of the building stock over time, taking into account renovation rates, new construction, and dropout rates. This modelling shows whether the EPBD’s 2030 target, a 16% reduction in average primary energy use per square metre in residential buildings, is likely to be met under current policies, or if renovation rates and incentives need to be boosted.
Embedding these insights into National Building Renovation Plans ensures that policies are not based on assumptions but on evidence-driven scenarios. For example, Estonia’s modelling has already revealed that deep renovation rates below 1% annually are insufficient, highlighting the need for stronger incentives and better funding mechanisms to approach the ~2% annual deep renovation rate implied by the EPBD’s targets.
BUP: With regards to progressive renovation strategies, how can Member States calculate and verify the Energy Performance of Buildings Directive (EPBD) target to reduce the average residential building stock energy use by 16% by 2030?
JK: To calculate and verify the EPBD’s 16% reduction target for residential building stock, Member States need to develop a building stock energy calculation model anchored in a clear baseline year (2020). The model should combine:
Using these inputs, countries can simulate energy demand trajectories to 2030 and estimate the reduction in average primary energy use per square metre across the residential stock. For example, Estonia applies four main building categories: non-renovated buildings, renovated buildings, relatively recent buildings built after 2000, and nearly zero-energy new builds, to model progressive stock transformation with realistic renovation pathways.
Verification requires linking these projections to national energy statistics, ensuring that calculated trends align with actual measured energy consumption in the residential sector. Estonia combines its national building registry with energy data for electricity, district heating, and fuels, enabling cross-validation of the model’s outputs. Such verification allows to adjust heat sources (heat pumps, district heating, gas boilers, etc.) to correspond to the real situation, because the building registry data might not always be up to date. Often, an old boiler has been replaced with a heat pump that may not be updated to the registry.
Importantly, these models also help identify policy gaps. Estonia’s analysis shows that its deep renovation rate, currently below 1% annually, is insufficient to meet the 16% target, implying the need for scaled-up incentives and funding mechanisms to approach an annual ~2% deep renovation rate. Furthermore, factors such as the decreasing primary energy factor of electricity (e.g. from ~1.9 today to ~1.6 by 2030) can support compliance but are not enough on their own without accelerating renovation efforts.
BUP: Drawing on your cross-border experience in Estonia and Finland, what do you consider the critical enablers and risks when implementing MEPS for non-residential buildings?
JK: Successful implementation of Minimum Energy Performance Standards (MEPS) for non-residential buildings relies first and foremost on the availability and quality of Energy Performance Certificates (EPCs). Since MEPS requirements are applied per individual building, EPC coverage must be as complete as possible.
In Estonia, a major initial challenge has been that many existing non-residential buildings lack EPCs. To comply with MEPS, owners must first obtain certificates, which can require scaled-up assessment campaigns supported by consultants and, where needed, incentives. By contrast, Finland uses calculated EPCs for existing buildings, ensuring broader and more consistent data coverage from the outset.
Another enabler is the robustness of EPC methodologies. Estonia, for instance, historically used EPCs based on metered energy data, which often included non-EPBD-related energy uses (e.g. process energy in industrial or mixed-use facilities). To avoid distorted ratings, Estonia is now adapting its EPC framework to:
Equally critical is ensuring that EPC scales align with MEPS thresholds. Since MEPS target the worst-performing buildings (e.g. those in class G), EPC classes must accurately reflect true performance levels. In some cases, recalibrating EPC scales may be necessary so that the lowest class truly captures the bottom segment of the stock.
Finally, while the number of non-residential buildings is typically smaller than the residential stock, many are large and complex. This makes the EPC issuance process manageable but time-sensitive, requiring sufficiently trained assessors and clear procedural guidance. Without complete and consistent EPC data, MEPS enforcement risks being uneven or ineffective.
BUP: How can EPCs, Renovation Passports, and the Smart Readiness Indicator (SRI) guide long-term, staged renovations?
JK: EPCs remain a crucial starting point by providing a snapshot of a building’s current energy performance and, in many cases, basic recommendations for improvement. However, EPCs alone rarely offer the detailed, step-by-step guidance needed to plan a full transformation towards zero-emission buildings by 2050.
This is where Renovation Passports (RPs) become a game-changer. They provide a tailored roadmap for each building, identifying specific, sequenced measures to achieve staged renovation in an optimised and cost-effective way. For example, they can recommend when to insulate, upgrade heating systems, or install ventilation with heat recovery, ensuring that each intervention aligns with the building’s long-term performance trajectory and avoids lock-in effects.
The Smart Readiness Indicator (SRI) complements these instruments by focusing on a building’s digital and operational potential. It assesses how ready a building is to integrate smart technologies like demand-controlled ventilation, PV integration, battery storage, and electricity price-based control of heat pumps. While the SRI may be more straightforward to apply in new or highly automated buildings, its role is growing as flexibility, grid interaction, and digitalisation become integral to the energy transition.
Together, EPCs, Renovation Passports, and SRI form a complementary policy toolbox:
For building owners, this integrated approach turns what might seem like fragmented policy tools into a coherent strategy for achieving cost-effective, staged, and future-ready renovations.
BUP: How can Indoor Environmental Quality (IEQ) be positioned as a driver, not just a co-benefit, of MEPS and staged renovations in practice?
JK: Indoor Environmental Quality (IEQ) must shift from being treated as a secondary benefit to becoming a core driver of renovation strategies. In practice, this means embedding ventilation, thermal comfort, and air quality requirements directly into Minimum Energy Performance Standards (MEPS) and staged renovation frameworks.
One common issue arises when buildings are insulated and air-tightened without improving ventilation. While such upgrades lower energy demand, they often compromise indoor air quality, leading to stale air, drafts, or thermal discomfort. In colder climates, for example, mechanical exhaust systems without heat recovery can cause cold draughts in winter, prompting occupants to switch off ventilation systems entirely, undermining both health and energy efficiency objectives.
To avoid this, renovation schemes should mandate minimum ventilation standards and promote solutions like heat recovery ventilation, which ensures a fresh air supply while maintaining energy performance. In non-residential buildings, the situation is somewhat easier: most already have ventilation and cooling systems, so the focus shifts to upgrading existing systems through efficient fans, heat recovery, demand-controlled operation, and improved building automation.
In residential buildings, however, IEQ considerations are even more critical. Highlighting healthier indoor environments, thermal comfort, and improved well-being can motivate building owners and occupants to undertake renovations. When renovation outcomes are communicated not just in terms of energy savings, but also in better living conditions, IEQ becomes a powerful driver for action.
By explicitly integrating IEQ into MEPS and staged renovation pathways, policies can deliver buildings that are not only energy-efficient but also healthier and more comfortable, creating stronger incentives for households and businesses to invest in deep renovations.
