Background

Vicky Albert-Seifried is a project manager in the 'Climate-Neutral Cities and Districts' group at Fraunhofer Institute for Solar Energy Systems (ISE) in Germany. She manages projects and activities in the fields of sustainable energy planning, urban energy transition, and climate-neutral cities. She is the coordinator of the Horizon Europe project WeGenerate, Chair of the COST Action 'Positive Energy Districts European Network’, Subtask Leader of the IEA Annex 83 on Positive Energy Districts, and an active member of the European Energy Research Alliance Joint Programme Smart Cities (EERA JPSC).

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BUILD UP (BUP): Article 10 of the revised EPBD mandates solar readiness for all new residential buildings by 2030 and non-residential buildings by 2027. From your perspective, what are the principal technical challenges and regulatory constraints that buildings must navigate to implement these solar mandates at scale?

Vicky Albert-Seifried (VA-S): The recast EPBD Article 10 aims to boost large-scale solar energy deployment. There is no doubt that this push will accelerate the decarbonisation of the built environment, but for effective implementation, there are still technical hurdles to overcome. Concerning photovoltaics (PV), the high penetration of intermittent generation into electricity grids can pose a significant challenge to grid stability. Therefore, alongside the solar readiness mandate, grid readiness is key to the transition. At the consumer end, battery storage with smart control at the building or community level can help ease the grid stress, but more incentives are likely needed to support their adoption. Besides PV, other solar technologies, including solar thermal and hybrid PVT, should be considered to meet heating needs, particularly in buildings with high heating demand. However, the uptake of different solar technologies will depend on how the EPBD provisions are transposed into national legislation, and what sort of technical and financial measures are provided by Member States to support solar deployment in buildings. As an active researcher in this field, I am excited to see how the EPBD will be turned from paper into reality in the coming years.

BUP: The EPBD introduces the concept of ‘solar-ready’ buildings and aims to deploy 150–200 GW of rooftop solar capacity across the EU. How can urban planning and building design evolve to support this ambition, especially in dense or historic urban areas?

VA-S: Large-scale solar deployment in dense or historic urban areas presents a unique set of challenges, with the common issues including limited space, weak structural integrity in ageing buildings, and the potential conflicts over preservation of heritage value. To support the EPBD ambition, different measures are needed for new and existing buildings, respectively. For new developments, incentives can be offered to encourage optimal building design and orientation that maximise solar harvest. Building-integrated photovoltaics (BIPV) that blend with architectural elements should become standard in new buildings. For existing buildings, particularly those with historic value, a main concern stems from the aesthetic impact of solar installations. In such cases, strategic placement—prioritising installations in locations not easily visible from public viewpoints—and the use of BIPV (e.g., solar roof tiles or solar façades) that mimic traditional materials to help maintain architectural integrity could be good approaches. For ageing buildings with weak structures, modern lightweight PV systems or non-invasive mounting systems could be an option. However, these applications still need further exploration, both technically and economically. With the push from the recast EPBD, I expect to see more experimentation with novel solar installations especially in dense and historic urban areas, in the coming years.

BUP: Solar energy is increasingly being integrated with other smart building technologies such as energy storage, heat pumps, and digital energy management systems. What are the most promising synergies you see in PV and thermal integrations, and how can they be leveraged to maximise building performance and user comfort?

VA-S: As PV costs and feed-in tariffs continue to fall—often below retail electricity prices—self-consumption of PV-generated electricity becomes crucial for maximising the return on PV systems. For this reason, PV and thermal integration is an economically attractive option, especially for small-scale prosumers. The coupling of PV and heat pumps, in particular, represents a highly efficient and economical way to heat and cool buildings. The electricity generated by PV can directly power the heat pump, significantly increasing the PV self-consumption and in turn, reducing electricity costs for operating the heat pump. In the face of climate change, with many European cities are experiencing longer and warmer summers, the use of PV-generated electricity to power heat pumps for cooling could be a sustainable way to increase thermal comfort in the built environment. There is a conventional belief that the use of heat pumps makes sense only for modern buildings. Nevertheless, recent studies have shown that, with targeted renovation and the clever combination of technologies, heat pumps can operate efficiently and economically even in older buildings without major interventions.

‘The coupling of PV and heat pumps represents a highly efficient and economical way to heat and cool buildings’

BUP: The directive also emphasises whole life-cycle carbon accounting and the phase-out of fossil fuel boilers. How can solar technologies contribute to reducing both operational and embodied carbon in buildings?

VA-S: Solar technologies offer a powerful dual solution for reducing carbon emissions in buildings. The coupling of PV with heat pumps, as explained earlier, is a highly efficient heating solution for buildings. Alternatively, solar thermal systems or hybrid heating systems that combine solar thermal with a boiler could potentially replace fossil fuel boilers. On the operational side, both solar thermal and PV–heat pump systems harness solar energy for heating, directly or indirectly. This replaces the need for fossil fuels and thus has a direct impact on carbon reduction. For embodied carbon, both PV and solar thermal panels have a relatively short carbon payback time—i.e., the time it takes for a system to offset the carbon emitted during its production through clean energy generation—often within a few years. This means that over their lifetime—typically 25 to 30 years—the panels will generate zero-carbon energy for decades after their embodied carbon has been paid back.   As the global focus shifts from operational efficiency to whole life-cycle carbon, the role of solar becomes even more central to achieving a truly decarbonised built environment.

BUP:  Through your direction of EU-funded projects such as WeGenerate, how can citizen engagement and co-creation accelerate the adoption of solar technologies in the built environment, particularly in vulnerable or energy poor communities?

VA-S: A just transition, ‘leaving no one behind’, is the motto of the UN Agenda for Sustainable Development. In WeGenerate, we are demonstrating how this can be realised through integrated and inclusive urban regeneration in four European cities: Cesena (IT), Cascais (PT), Bucharest (RO), and Tampere (FI). The project aims to help the demo neighbourhoods reinvent themselves and, in the process, create positive changes, new values, and opportunities. Sustainable urban regeneration is a complex undertaking; it is not only about the cities’ ambition, and the use of technologies (both physical and digital) but, most importantly, about the people. For instance, in Cascais, we are working with social housing residents and local schools to co-create an energy community powered by PV and a smart energy management system. The solar electricity generated will be shared with social housing residents to alleviate energy poverty, and with schools to raise awareness of the climate-neutral transition. For this, citizen engagement is key to fostering a sense of ownership, trust, and shared benefits in the project. Full backing from the community is crucial for accelerating the process and realising the goal in the end.

‘Sustainable urban regeneration is a complex undertaking; it is not only about the cities’ ambition and the use of technologies (both physical and digital), but most importantly, about the people’

BUP: Considering your role at the nexus of technical innovation, policy development, and stakeholder engagement in solar energy and climate-neutral urban planning, which fundamental technical skills and interpersonal competencies do you consider indispensable for professionals entering this interdisciplinary field today?

VA-S:  In the field of sustainable urban transition, I consider myself an enabler of RDI collaborations on the ground. This role requires close interaction with cities, technical professionals from various sectors (e.g. urban planning, building, energy, mobility, ICT), as well as social scientists, among others. To lead RDI activities in such an interdisciplinary environment, one does not necessarily need deep expertise in all fields, but having broad knowledge across multiple areas and recognising key challenges in different domains are important. Additionally, urban transition is a shared endeavour among different stakeholders, and its success relies on effective teamwork. For this, leadership and interpersonal skills that help build trust and convey shared values within the team are paramount. No matter the skill set, it is important to recognise that the path to transition is not always linear but often filled with uncertainties. There are moments when a project feels stuck, but one needs the ability to embrace change, maintain enthusiasm and devise new solutions together with the team.