The drive to build and the imperative to preserve

Architecture transforms space, yet sustainability is an invitation to restraint: a fundamental challenge of contemporary construction opens up between these two principles. We discussed this with Professor Ena Lloret-Fritschi and Professor Muck Petzet, Director and Co-Director of the new Institute of Sustainable Architecture and Technology (IAST) at the USI Academy of Architecture, in a contribution produced in collaboration with laRegione.

Architecture is, by definition, an act of transformation. It shapes space to meet human needs, designing buildings and environments of various types and uses. Yet, every construction intervention inevitably involves a loss: something is altered, removed, or destroyed. Sustainability, on the other hand, aspires to minimise environmental impact. Bringing these two concepts together reveals a fundamental tension—almost an oxymoron—between the drive to build and the imperative to preserve.

We discussed this tension, as well as the meaning of sustainable architecture today and future challenges, with Professor Ena Lloret-Fritschi and Professor Muck Petzet. The institute—officially inaugurated on 16 April—brings together expertise in heritage, construction, reuse, structural engineering, and digital technologies, aiming to approach sustainability in an integrated, multidisciplinary way.

What does it mean to practice sustainable architecture?

For Prof. Muck Petzet, the result of pairing architecture and sustainability defines an important starting point. "Building new structures requires considerable resources and energy and therefore has a significant environmental impact. Quoting Luigi Snozzi: 'Every intervention involves destruction; destroy with intelligence.' As architects, we have a responsibility to question the necessity of the act itself. We must ask ourselves if an intervention, and particularly a new construction, is truly necessary, or if we can work with what already exists." In this view, reuse is not just one choice among many, but the priority approach. Prolonging the life of buildings by adapting them and preserving their material and cultural value reduces both emissions and resource consumption. "Temporary structures concentrate their emissions into a short window, whereas durable buildings allow that environmental cost to be spread over time," observes Muck Petzet. Sustainability, in this sense, begins with continuity rather than replacement.

Prof. Ena Lloret-Fritschi, for her part, frames the issue from a complementary perspective, focusing on how to act when intervention becomes necessary. "Practising sustainable architecture means, first and foremost, becoming aware of the impact of every single intervention." The challenge isn't about avoiding transformation altogether; instead, it's about defining concrete paths to act with responsibility and precision, aware of the environmental price of every choice. This requires the development of tools that foster a deeper and faster understanding of existing buildings, revealing their structures, constraints, and potential from the earliest stages of the design process. Thanks to digital technologies and AI integration, it is now possible to thoroughly analyse a building in the preliminary phases, thereby defining targeted intervention strategies. In this light, technology becomes the driver of more conscious and informed action.

At IAST, this approach follows a clear hierarchy of interventions: first, reuse and repair; then, transformation; and, only as a final stage, demolition and new construction. In this context, sustainability is not an accessory, but the very essence of the principles that guide every choice at every level of design. This also implies a change in mindset regarding what we preserve, what we transform, and what we remove. Instead of maximising production, the focus shifts to reducing material use, responsible material selection, and optimising structural systems. The goal is not merely to contain impact, but to create resilient architectures—works capable of lasting, being repaired, and evolving with the climate. In this new paradigm, structural simplicity and robustness become the guiding criteria to eliminate complexity and reduce maintenance costs whenever possible.

The entire life cycle of all components

More broadly, IAST's work is part of a larger disciplinary shift toward a culture of durability. Buildings are increasingly understood not as short-lived objects, but as structures that should endure, adapt, and be valued over time. This transition is the subject of heated debate regarding post-war building stock. Although often considered obsolete or lacking aesthetic merit, these structures contain precious materials and large amounts of stored carbon; their recovery therefore represents an extraordinary opportunity for the environment. In this context, the work developed at the institute spans different but closely related domains. It includes the conservation and transformation of modernist buildings, where repair becomes a central strategy, as well as the careful evaluation and adaptation of existing structures alongside the design of new ones. Structural considerations play a key role at all levels of intervention, ensuring safety, durability, and the efficient use of material resources.

This perspective also extends to more recent building heritage. Many structures from the 80s and 90s are reaching a point where intervention is necessary, yet they are often demolished to allow for urban densification. This raises an important question: how can we balance the need for transformation with the responsibility to preserve and reuse what already exists? For Prof. Lloret-Fritschi, sustainability is also "a matter of processes and material flows," from extraction to transformation, assembly, and eventual reuse. Even when intervention is necessary, how materials are used becomes central. Ideally, this includes consideration of the entire life cycle, even if this remains a goal rather than a fully achievable condition.

Design, material, fabrication, and structural integrity must be conceived together. Geometry can become an important lever for reducing material use, while durability remains essential. In parallel, the production of structural elements must be conceived to promote a circular economy and reduce waste, aiming to optimise the use of matter. In this way, design choices are inextricably linked to construction processes and resource management. Prof. Muck Petzet completes this vision by emphasising the importance of context: "We can learn a lot from vernacular architecture," he observes, pointing to the intelligence inherent in local materials and design capable of responding to the climate. At the same time, globally sourced materials remain an integral part of contemporary construction but require more careful evaluation: "Thinking sustainably also means resisting the logic of the cheapest option and considering the broader consequences, including the impact on local economies."

Buildings integrated into their context

This reflects a broader condition: while knowledge can circulate globally—supported by digital technologies—materials remain tied to the place. The task is therefore to navigate between these scales, making informed decisions that respond to both the context and its constraints. Energy remains an important aspect, but both architects emphasise that it is only part of the equation. Passive strategies—orientation, natural ventilation, and thermal mass—remain fundamental. The buildings themselves can act as environmental systems, regulating the climate through their material and spatial properties rather than relying exclusively on technical systems. For the Director of IAST, this implies rethinking design priorities: "Geometry, structure, and materials offer great potential, but they must be considered together from the start." Performance should not be an afterthought added to a project, but integrated into its conception. In this sense, technology supports a more efficient and precise use of resources. At the same time, both USI professors emphasise that sustainability cannot be reduced to simplified certifications or metrics. "There is no single solution," notes Lloret-Fritschi. "Sometimes it makes sense to use earth, sometimes wood, sometimes concrete: the key is making conscious choices." Digital tools can assist in this process, but they do not replace judgment. And economic constraints remain a central challenge. Often, sustainability clashes with the logic of immediate savings. Reuse can be complex and expensive, while new construction is often cheaper. As Muck Petzet observes, "if we focus only on the lowest cost, sustainability becomes unreachable." This highlights the need to shift from initial cost to long-term value.

A mindset

Ultimately, the vision of the two architects converges on an essential point: sustainability is not an accessory to be added to a project, but a mindset (forma mentis) that pervades every phase, from the radical choice of whether to build or not, to the methods of intervention, to the building's performance in the long term. The current transformation of cities, increasing resource constraints, and changed environmental conditions make this shift necessary and urgent. The question is no longer whether to build sustainably, but how to do so responsibly and realistically. For Prof. Muck Petzet, the direction is clear: "In the future, sustainable architecture will not remain a choice; it will become the norm." Director Lloret-Fritschi adds that this transition will depend not only on innovation but also on the care with which we work with what already exists. At IAST, these perspectives merge. The institute positions itself at the intersection of heritage and construction, reuse and innovation, structure and technology, approaching sustainability not as a predefined model, but as a method of practice and research. It is an approach that begins with a careful understanding of what already exists, prioritises reuse and repair, and only then considers transformation and new construction, aiming to build less, build better, and build to last.

Content produced and published in collaboration with laRegione.