Please fnd attached:

In the 21st century the world population faces unprecedented planetary challenges – in this context, the planetary boundaries model, which shows the ecological stress limits of our earth systems, can be understood as the guiding framework needed for future transformation processes. For a post-fossil world that provides a healthy and happy livelihood for many people and living beings, a new vision is needed. The question »How do we manage the transition?« is inevitably accompanied by the question »What will this world look like?« The forthcoming

sbe22 berlin conference will be a unique

and transdisciplinary collaboration and exchange between science, politics, industry and civil society which is needed to meet this

challenge.

opportunity to provide a platform for integrative

Our program and schedule for

orientation during the conference

sbe22 berlin – Built Environment within Planetary Boundaries

Book of Abstracts

Universitätsverlag der TU Berlin

Editors:

Tear of here

Message to Montreal:

environment within planetary boundaries.

indicators and necessities for a built

berlin conference in terms of potentials,

Please tell us your key essence of the sbe22

would like to see presented in Montreal?

What is the message from Berlin that you

sbe22 berlin –

Built Environment within Planetary Boundaries

in the future.

The global climate crisis requires us to

want to live, work, consume and build

develop new understandings of how we

Eike Roswag-Klinge, Thomas Lützkendorf, Kristin Wellner,

Alexander Passer, Guillaume Habert

ISBN 978-3-7983-3257-7 (print) ISBN 978-3-7983-3258-4 (online)

sbe22 berlin – Built Environment within Planetary Boundaries

#### Book of Abstracts 7

argering F

sbe22 berlin -Built Environment within Planetory Boundories Book of Abstracts

Editors: Eike Roswag-Klinge, Thomas Lützkendorf, Kristin Wellner, Alexander Passer, Guilloume Habert

7 Universitätsverlag der TU Berlin

#### Table of Contents

8

#### Circularity I – Circular Material Systems s.1

#### Circularity II – Circular Economy of the Building Sector s.2

#### Circularity III – Reuse in Buildings and Materials s.3

#### Building Stock I – s.4 Refurbishment and Retroftting

### Building Stock II – s.5 Refurbishment and Retroftting

#### Buildings – Urban Timber s.6 Construction

#### s.7 Sufciency

#### s.8 Critical Digitalization

#### s.9 Optimization

#### Climate Neutral Buildings I – s.10 GHG Reduction Strategies

#### s.11 Climate Neutral Buildings II – Benchmarks ZEB

#### s.12 Education in Architecture and Planning

#### sc.1 Transformative Spaces – Experimental Large-Scale Projects

#### sc.2 Material Flows and Commodity Chains

#### psc.1.1 Design and Processes – Reduce, Reuse, Recycle

#### Materials I – s.13 Clay and Mineral

#### Materials II – s.14 Wood and Mycelium

#### Materials III – s.15 Concrete and Cement

### Urban Planning I – s.16 Housing Strategies

### Urban Planning II – s.17 Circularity and Energy Renovation

#### Urban Governance – s.18 Socio-Political Frames for Transition

#### s.19 Life Cycle Assessment I

#### s.20Life Cycle Assessment II

#### Life Cycle Assessment III – s.21 BIM/LCA Application Cases

#### Life Cycle Assessment IV – s.22 EPD/LCA

#### s.23 Innovation & Economy I – Transformative Projects

#### s.24 Innovation & Economy II – Sustainable Business Models in Building Economy

#### s.25 Infrastructure – Civil Engineering and Transport Infrastructure

#### ps.26 Poster Session A

#### ps.27 Poster Session B

#### Special Fora sf

#### Workshops ws

#### Excursions e

#### Welcoming Addresses

28

Dear sbe22 berlin participants,

the recently published IPCC report has again restated the need for us to radically change the way that we live, work, consume and build in the face of an acute global climate emergency. The production and maintenance of our built environment is responsible for an unacceptably large proportion of global carbon emissions, energy production and resource consumption. The need for us to exist within planetary boundaries has never been greater.

Triggering these transformation processes will require building new proactive alliances - in this sense we are thrilled to welcome you to the Sustainable Built Environment D-A-CH Conference 2022 in Berlin. The conference ofers a trans- and interdisciplinary platform for international scientists, practitioners, politicians and interested guests to exchange their knowledge and experiences related to the key themes of the conference: resource management and material fows, climate neutral buildings, post-fossil infrastructures, critical digitalization and socio-political frames for transition. The aim of the sbe22 berlin conference, hosted by Natural Building Lab, TU Berlin in cooperation with KIT Karlsruhe, ETH Zürich and TU Graz, is to use shared expertise to formulate the ideas that will be presented at the World Conference in 2023 in Montréal.

The sbe22 berlin D-A-CH conference, as part of the 2021–2023 cycle of the SBE conference series, represents an important milestone for the implementation of the climate protection agreement of the City of Berlin and the sustainable development planning of the Technische Universität Berlin. Berlin's character as an international hub for research and innovation provides the opportunity for participants and their works to set new local and global impulses, strengthen communal strategies for climate action, create a cleaner construction sector and enact holistic approaches for the transformation towards a post-fossil society.

The sbe22 berlin D-A-CH chair and organizers thank all the authors and members from the Scientifc Committee for their contributions and are looking forward to four inspiring, empowering and pioneering conference days.

#### Dear sbe22 berlin participants

having been thoroughly efective in enforcing boundaries to address a variety of problems for quite some time, we defnitely have been hesitant about limiting ourselves when it comes to the building sector. Yet, the idea of creating boundaries is essential concerning the harmful impact our unlimited human behavior has on the planetary environment.

The TU Berlin feels honored being the host of sbe22 berlin and to enable an exchange of knowledge and ideas for sustainable solutions and future-oriented innovation regarding the building sector. At this point I would like to mention the Natural Building Lab which follows the principles of a post fossil, ecological and socio-political sustainability including social responsibility, and which also hosts the sbe22 berlin in cooperation with KIT Karlsruhe, ETH Zürich and TU Graz.

We must make it compulsory to take CO₂-emissions into consideration at all stages of a building process. Greened roof areas, electrical heating and sustainable resource management are just a small part of what we must think about during the next decades. How can the challenge of bringing sustainability, climate protection and economy into accordance be met? How can we, e.g., ensure a fair and sustainable water supply regarding the operational optimization of local water infrastructure concerning demography, climate change and socioeconomics?

It needs a new understanding of how we want to live, work and consume.

Since we can´t consume and build endlessly in a fnite world, we must be aware that giving a small part back of what we took from our planet is essential.

The problems we are facing today have direct consequences for tomorrow. Sustainability must not be an ad on but rather a must-have for

each building project.

We will be delighted about a numerous participation in many planned events during the sbe22 berlin. Furthermore, we wish you all the best and an exciting conference.

Yours Sincerely,

Geraldine Rauch President of Technische Universität Berlin

Today, humanity is facing challenges of global dimensions – most of all, the consequences of man-made climate change, and related to this, the urgent need for an energy transition. Time is short, and already now, the world is dealing with terrible conficts, driven by competition for resources. Indeed, the frst half of the 21st century is the crucial era for fnding solution to long-term societal challenges. Engineering will play an essential role here: a new role, that cannot be defned by economic interests alone.

Crises, whilst ofen difcult to manage, are pacemakers in the evolution of mankind. Stability has always been an illusion, wishful thinking, only possible for short periods. In particular, the expansive growth of economy over

the last centuries has become a drive also for global change: today, we live in the Anthropocene, and »untouched nature« is hard to fnd on our planet.

KIT, the Research University in the Helmholtz Association, has defned its mission: to create and impart knowledge for the society and for the environment. With over 10000 staf and more than 25000 students, KIT envisions to enable and live the change towards a sustainable future. For this, many new technologies are being developed at KIT, including research on renewable energies and energy storage, biofuels and sustainable bioeconomy, new materials, post-fossile infrastructure, big data, machine learning and artifcial intelligence, shared mobility, sustainable resource management, as well as in civil engineering, architecture and construction.

KIT, ofcial Partner of »sbe22 berlin – the Sustainable Built Environment D-A-CH Conference 2022«, sends all participants the very best wishes for a successful conference.

Yours Sincerely,

Prof. Dr.-Ing. Holger Hanselka President of Karlsruhe Institute of Technology (KIT)

Sustainable development is one of the most important challenges of our time. We are facing a major global task and with it a common duty, which requires a comprehensive approach that involves resilient solutions not just in each (scientifc) sector but also a transdisciplinary foundation. Therefore, we at Technische Universität Graz (TU Graz) are aware of our role as an educational and research institution and have committed ourselves to fnd viable solutions for sustainable development with all our expertise. This especially involves the construction and operation of buildings, as with an amount of 37 % of global CO₂ emissions, it is one of the largest single emitters of greenhouse gases and holds therefore enormous potential in the fght against climate change.

In its Field of Expertise »Sustainable Systems«, one out of fve internationally outstanding research areas of TU Graz, researchers from all seven faculties work together to form a basis in the sense of an extensive, transdisciplinary research, which also is implemented in teaching. Together with establishing the Sustainability Advisory Board, as a central body for a sustainability strategy, TU Graz flled the endowed professorship for sustainable construction. Furthermore, in June 2022 the Center of Sustainable Construction, that combines the activities of several groups on sustainability in the construction sector at our university, opened. Additionally, the TU Graz wants to operate in a climate-neutral manner from 2030 and has therefore developed a roadmap with numerous individual measures.

Knowing that international cooperation is a huge part of the transformation process, we are glad that the sbe22 berlin is held as a D-A-CH initiative, which involves academic institutions in Germany, Switzerland

and Austria. Moreover, we are particularly pleased that an additional student conference is ofered this year, giving students the opportunity to present their research, as in the context of sustainable development the involvement of all generations is essential.

We gladly look back to successful collaborations in the past years and wish you a fruitful and inspiring conference 2022!

Yours Sincerely, Harald Kainz President of TU Graz

Dear sbe22 berlin participants

The construction industry accounts for over 40 % of all material extracted as well as 40 % of total energy and 16 % of annual water consumption. During the last century, consumption of construction minerals multiplied by a factor of 42. As all these processes entail a heavy carbon footprint, it becomes clear that business-as-usual practices are not sustainable and new approaches need to be implemented. But one can also turn these challenges into opportunities.

Future construction can be a way to reduce or even store carbon emissions when built with selected building technologies. They can also be used as depositories of materials to be later mined. Building renovation can be a catalyst to re-activate social and economic networks in a neighborhood.

To harness these opportunities, ETH Zürich is strongly engaged in research and innovation towards a post carbon environment.

Apart form research and tech transfer the education of a new generation of scientists, engineers and architects is vital for a successful transition to net zero. We want our students to acquire the fundamental knowledge and methods to tackle these challenges. But also, and most importantly to have a critical thinking so that they can engage with society by developing and designing the appropriate solutions to the needs of future generations.

The conference on the Sustainable Built Environment, sbe22 in Berlin, is part of a major international series of conferences that are supported by several important initiatives and alliances in the realm of sustainable construction. The series, now on a three-year cycle, is recognized as the world's preeminent conference series in this important feld.

I am delighted to see the joint initiative from German, Austrian and Swiss universities to co-organize this conference. It is hosted by the TU Berlin in collaboration with Karlsruher Institut für Technologie , TU Graz and ETH Zürich.

I wish you all the success for the conference and hope that under this shared roof you, as researchers or industry partners, will have fruitful discussions on how to progress towards a net zero emission-built environment.

Yours Sincerely,

Joel Mesot President ETH Zürich

#### Dear sbe22 berlin participants

This conference sbe22 Berlin is taking place at a time of great change in European policies for the built environment. Since the arrival of the Von der Leyen Commission, a multitude of policies af ecting buildings and infrastructure have been either proposed or revised. This includes initiatives on energy and climate, environment, f nancing and investment, digital innovation, and even the creative process with the New European Bauhaus. Of course, there are strong drivers for this change. First, our changing climate and Europe's legally binding goal to be climate neutral by 2050. Second, the digital transition which is enabling new business models such as a circular economy. Third, the geopolitical context is also changing before our eyes. The recovery from the COVID-19 pandemic and more recently the Russian war in Ukraine have shone a light on the resilience of supply chains, including for construction, as well as our dependency on fossil fuels.

From now to 2050 the European built environment will undergo a transformation. The majority of buildings standing today need to become energy ef cient and decarbonized, as active participants in a renewable energy system. This needs a massive ef ort of renovation works, which is why the Commission proposed the Renovation Wave, to retrof t 35 million building units this decade, and to continue at that pace through to 2050. At the same time, we need to ensure this increased activity is carried out in a resource-eff cient way. Construction generates over a third of the EU's waste, and uses half of all resources extracted. In order to achieve a sustainable built environment, the construction industry ecosystem also needs to undergo a transition. The Commission is therefore developing a Transition Pathway for construction to become more digital, green and resilient. In this context I am looking for-

ward to this conference and all the new ideas it will bring.

Yours Sincerely,

Philippe Moseley Policy Of cer, Sustainable Industrial Policy and Construction European Comission, DG GROW

Welcome to sbe22! Issues of building for the future and of sustainable neighborhood and urban development are very relevant today. I am especially pleased that institutions in Austria, Germany and Switzerland have jointly prepared this platform for dialogue with industry, academia and policy-makers, and that the conference has attracted interested participants from around Europe and beyond.

The topics addressed here in Berlin are central concerns of Germany's Federal Ministry for Housing, Urban Development and Building as well. In line with the title of this year's conference, »Built Environment within Planetary Boundaries«, our ef orts are focused on preserving the resources on which our lives depend.

One important goal is to make our

building stock climate-neutral, which we hope to achieve through sustainable construction. That means paying attention to greenhouse gas emissions over a building's entire lifespan. We are working to establish this as a standard parameter for targets, planning and assessment. Requirements that are not tied to specif c technologies or materials give more decision-making discretion to those responsible for building, enabling them to seek cost-ef ective solutions based on the latest research and technology which are best suited to the individual case. This is one basis for ensuring that prices and rents remain af ordable for all segments of society.

Increasing the application of digital technology in the construction value chain is another important goal of mine. The use of digital methods such as openBIM helps to signif cantly increase the productivity and ef ciency of Germany's construction industry.

Through the Alliance for Af ordable Housing, the timber construction initiative and our role as national contact point for the New European Bauhaus, we are actively supporting the necessary processes of transformation.

I hope all participants f nd this year's sbe22 interesting and inspiring, with lively discussions and intensive exchange among professionals in the f eld.

Yours Sincerely,

#### Cansel Kiziltepe

Parliamentary State Secretary to the Federal Minister for Housing, Urban Development and Building

Considering the climate emergency, decrease of raw materials and scarcity of space for landflls, the construction sector's extensive resource consumption needs to change. Thus, establishing a circular economy that saves natural resources is a key priority of the Berlin Senate. In June 2021, the Berlin House of Representatives adopted the ambitious Waste Management Concept 2030 under the guiding principle of Zero Waste. This concept calls for the consistent expansion of reuse and recycling of material fows, which is to close material cycles and signifcantly reduce the waste of natural resources.

The measures for sustainable construction that Berlin has initiated have provided an important impetus. Since December 2021, the new Administrative Regulation for Procurement and Environment makes the reuse and recycling of building materials mandatory for the demolition of public buildings. It also stipulates the use of sustainable building materials in new construction and civil engineering.

Furthermore, we have developed a practical decision-making tool for sustainable housing construction. It shows that the substitution of four conventional building elements with climate-neutral building materials alone can save around 50 percent of harmful climate gas emissions. Such measures are now to be implemented for example by the Berlin owned private housing company Stadt und Land in several new multi-storey standard houses in the district of Berlin Neukölln.

Over the next few years, more than 16 new neighborhoods will be constructed in Berlin. The Senate Environment Department recently published a guideline for their resource-efcient development. For instance, the world's largest timber construction project will be designed and realized with the use of resource-saving secondary building

materials on the site of the former Berlin Airport »Tegel«.

All these measures have taken us signifcant steps in the direction of sustainable construction. We would like to share our experience and learn from your research. That is why I am particularly pleased to welcome you on behalf of the Senate to the sbe22 Berlin D-A-CH Conference in Berlin.

Yours Sincerely,

#### Bettina Jarasch

Senator for the Environment, Urban Mobility, Consumer Protection and Climate Action in Berlin

Dear sbe22 berlin participants

According to United Nations forecasts, around two-thirds of the world's population will live in cities in 2050. More than 75 percent of Germans already live in urban areas. Berlin's population is also growing – the four-million mark is expected to be reached in 2030.

The dangers of crossing planetary boundaries have been studied scientifcally for decades. What is lacking, however, is comprehensive research and innovation to develop systematic solutions to protect our planet and to make those available regionally. Society has to face these challenges as a whole.

The Climate Change Center Berlin Brandenburg is a transdisciplinary center for research and knowledge

transfer. Together with representatives from politics, business and civil society, scientists from Berlin and Brandenburg work on the implementation of the climate goals of the Paris Agreement for the metropolitan region. So far, research has not sufciently considered the subnational efects of the necessary transformation processes between actors, regions and nations. However, these analyzes are indispensable for the social acceptance of such a far-reaching structural change. It is desirable that the results of these trans- and interdisciplinary research projects are also achieved in the short term in order to be able to infuence current political decision-making processes. In addition, insights gained must be processed and made accessible to diferent target and age groups. We place a special focus on the Berlin-Brandenburg metropolitan region in terms of new solutions for networked urban and infrastructure planning, which imply innovative building materials, forward-looking mobility concepts as well as new land use ideas. It is necessary to involve stakeholders and citizens, because climate protection and climate adaptation strategies are tasks for society as a whole.

For this reason, we are particularly pleased to support the sbe22 Berlin D-A-CH Conference sustainable built environment within planetary boundaries as a scientifc partner organization and to accompany the transfer of knowledge into practice and politics.

Yours Sincerely,

Anita Dame Managing Director Climate Change Center Berlin-Brandenburg

Welcome to the sbe22 berlin D-A-CH conference

The sbe22 berlin D-A-CH conference, which will take place under the theme »Built Environment Within Planetary Boundaries«, will provide a platform for the exchange of ideas on innovative design and planning methods, building products, future-proof buildings and infrastructures as well as sustainable neighborhood and urban development. It is primarily aimed at participants from Austria, Switzerland and Germany, as well as from other European countries, and includes representatives from countries of the global south. Participants will be introduced to options for the further development of methodological principles, design, planning and evaluation tools, as well as concrete solutions and examples from the felds of products, buildings and urban planning. The scientifc sessions and several special events invite representatives from science, politics and industry to an in-depth exchange of experiences.

Europe has formulated ambitious goals for its sustainable development over the next decades and plans corresponding measures. Many of them directly and indirectly afect the construction and real estate sector, as well as the closely related energy supply. Buildings and infrastructures provide prerequisites for social and economic development and have a major impact on the quality of life of their occupants and neighborhood. However, they are also associated with undesirable energy and material fows, as well as efects on the global and local environment, which to prevent further harm, have to be minimized. Climate protection, resource conservation and health protection measures have to be designed in such a way that issues of economic efciency, value stability and afordability are taken into account. At the same time, buildings and infrastructures are already afected by the local consequences of global climate change and must be adapted to them. It will be necessary to achieve this by assessment of the

respective sites and planning with prevision of the developments of the next twenty years. The fact that the construction and real estate sector causes considerable energy and material fows, as well as environmental impacts, also points to the necessity of looking for potential for savings and reduction. The success of sustainable development thus also depends on the players in the construction and real estate industry, including upstream and downstream sectors. The construction and real estate sector is thus both a cause and a victim of the previous code of conduct of resource management of real estate industry and building sector, as well as a feld of action for solutions to change it.

More and more, the realization is gaining ground that economic and social development must take place within planetary boundaries. In selected areas, such as climate protection, the safe operating space has already been enacted, and the risk of serious consequences for humanity is increasing. It is therefore in everyone's interest to preserve the natural livelihood of mankind. The necessary goals have already been developed by science, which lead, for example, to a budget of still feasible greenhouse gas emissions while limiting global warming. But how can these goals be translated into concrete objectives, benchmarks and and target values in the design of buildings? Is orienting on technical and economic feasibility as well as on good examples still sufcient, or will benchmarks in the future also have to be oriented on science-based targets that can be derived top-down from planetary boundaries? This overarching question is one of the focal points of the conference and will be addressed in the sessions on *climate-neutral buildings* and *post-fossil infrastructures*. There will be discussed whether the preconditions for the introduction of binding requirements to limit greenhouse gas emissions in the life cycle of buildings are given and when this has to be done at the latest.

Instruments named in the TAXONOMY, as well as in the drafs of the construction product regulation (CPR) and the energy performance of buildings directive (EPBD), including LEVEL(s), point in the right direction, but do not yet contain binding requirements.

Planetary boundaries do not exist for all discussed topics. Although the model of a »resource-light« society exists as a reaction to the mega-trend of resource scarcity, concrete target values for the design of buildings are still lacking. Nevertheless, a new focus can be identifed in the topics discussed at the conference: the circular economy in the »construction« value chain and the recyclability of construction products, buildings and settlements. The possibilities in the felds of recording, evaluating and specifcally infuencing *material fows in the construction and real estate sector*, as part of *resource management*, will be presented and discussed. Corresponding consequences and approaches to solutions for the development, manufacture and use of products will be debated.

In the context of sustainable development, cities, and neighborhoods are emerging as an important object of consideration, as an infuential level of action and – through their administrations and representatives of civil society – also as relevant actors. Using municipal options make it possible to exert direct and indirect infuence on construction and development activities. Municipalities can currently react faster and better to new goals and challenges – also by using local building law and public procurement instruments – than it is possible in, e.g., national legislative processes. These topics will be addressed in the scientifc sessions and in the supporting program. The topics of further development of national, municipal and institutional *building stock* will also be addressed.

In all areas of material development, building design, as well as neighborhood and urban planning, the trend of *digitalization* provides important support. Current topics and trends will be discussed at the conference, including questions of life cycle analysis with its corresponding data bases and the need for related information, as well as on the use of BIM.

The trend towards the awareness of responsibility towards the environment and society, as well as the need for sustainable production and consumption patterns, is leading to new forms of information exchange and cooperation along the construction value chain and ultimately also has consequences for education and training in these felds. In the »Frames for Transition«, therefore, the possibilities for action for companies in the real estate industry are discussed and educational concepts are presented.

Questions of the future design of living and working environments with the implementation of a sufciency, consistency and efciency strategy will be discussed at the conference. This will be refected, among other things, in a special event on the *New European Bauhaus*.

With the program of SBE22 Berlin, the breadth and depth of topics in the feld of sustainable design of the built environment is once again evident. The strong momentum in the further development of scientifc foundations, political instruments and business models is also clear. The results of the SBE22 Berlin – as well as those of the other regional conferences worldwide – will be incorporated into the program of the World Conference WSBE23 in Montreal.

#### Introduction Student Conference

46

In summer semester of 2022, the Natural Building Lab and the Habitat Unit, both research centers of TU Berlin, invited students to an open call in the context of the Pop-Up Campus Aachen. Integrated into the discourse on building in the existing fabric, focus of the program is on approaches and processes of circular building, the handling of recyclable materials and on constructions with renewable or natural materials, as well as on research on urban and regional questions on renewable or natural commodity and material cycles. Discussed will be the experimental and future-oriented approaches of students, as well as the challenges and opportunities of research and methodology in architectural teaching. The program is organized at the TU Berlin as the student conference within the framework of the international conference on sustainable building »sbe22 berlin – Sustainable Built Environment Within Planetary Boundaries« and enables the students of the Pop-Up Campus to exchange ideas with international scientists and present their projects.

Since its foundation in 2018, the Natural Building Lab continuously develops its own teaching approach: »Teaching, Research, Practice«. As part of the focus on DesignBuild (focus: Dr. Nina Pawlicki) and Reallabore, several built projects have been realized under the transdisciplinary and collaborative cooperation (focus: PhD cand. Matthew Crabbe) between students, institutional and civil society actors. At the Natural Building Lab, experimental formats are tested in teaching for further methodological and content-related knowledge gain, and teaching research projects are initiated specifcally or developed together with students. A special focus lies in the questioning of the potentials and chances of real laboratories in planning and building. Realized projects: Infozentrale Vollgut, Oasis Tropical Moravia, Exil Austellung Anhalter Bahnhof. Prof. Elke Beyer is a specialist in research on the international commodity fows.

In this context, the standards of research in architecture have again come to the fore internationally. On the one hand, there is the question of what demands are made on contemporary research in architecture, not least against the background of the increasingly complex demands on the design process at universities, as well as on planning practice – and, on the other hand, there's the question of what perspectives are still missing or not sufciently taken into account in the discourse on architectural research and architectural education. The NBL is continuously dealing with these questions in its own teaching practice, especially by including the educational perspective, which can be seen as a missing component in the current debates. The Natural Building Lab participated with Prof. Roswag-Klinge in the conference »Research Culture in Architecture« 2018 at the TU Kaiserslautern and cooperates especially with the Habitat Unit at the TU to further develop the formats of teaching research. Important insight from the teaching practice so far is above all the need to include and diversify scientifc methodology in teaching in order to provide students with relevant methodology to identify, analyze and deal with problems and research questions on a theoretical, technical or mathematical level; so especially in transdisciplinary projects (interfaces: construction, economics, landscape and urban planning, sociology). Thus, the research state and question docks with the PUC.

The objective of the Open Call for the Student Conference is, on the one hand, the targeted selection of valuable student contributions on building in existing contexts, resource- and material-conserving construction, and on the other hand, a concrete contribution to the discourse on science and methodology in architectural teaching. The Students Conference enables students to participate and network with

scientists from the disciplines of sustainable design and construction and aims to test and deepen scientifc methodology and formats. A further goal is to gain knowledge by networking actors from the academic mid-level who actively deal with the interfaces of design and scientifc/theoretical work in their teaching. The goal in the area of science communication is the successful implementation of a prototype and poster exhibition of the selected student work at the Students Conference as a representation for a satellite of the Pop-Up Campus.

The Open Call for the Students Conference invites students to address the questions:

What experimental spaces are needed beyond the current building and planning law to test innovative and novel constructions and planning processes in order to derive new rules and parameters for a climate-appropriate building practice? Which processes/construction possibilities are particularly suitable for building in existing structures in the context of a climate-appropriate and resource-saving planning practice? On a process-oriented level, the workshop in Aachen and the Students Conference should contribute new insights to the following question: What formats are needed in architectural teaching to develop approaches to solutions for the complex challenges of the built environment on a theoretical, design and real-world level? How can the learner/student perspective be further integrated into research?

The student conference at the TU Berlin is accompanied by a workshop on »Educational Perspective on Research and Teaching in Architecture« in Berlin as a part of the Pop-Up Campus program. For this event, we announced an open call as part of the Pop-Up Campus. Students applied from all over Germany, with increased entries from Pop-Up Campus partner universities. Students applied with their current semester project or with an older project, based on a short abstract and complementary visuals. An advisory board of faculty and students reviewed the submissions and invited a number of students to prepare a full paper for the conference in Berlin in September.

A workshop on »Educational perspective on Teaching and Research in Architecture« is organized within the framework of the conference as an opening event in Berlin. The workshop is coordinated by the Natural Building Lab and the Habitat Unit and serves the networking of the participating universities in Aachen as well as the exchange between students and teachers on research, methodology and scientifc work in architectural teaching. During the workshop (20.09.), the diverse perspectives are exchanged and discussed along with the participating teams of the Students Conference through Input talks and workshop format.

Organizing Committee ದ Scientific Committee

#### Conference Chair Scientifc Chair

Thomas Lützkendorf Karlsruher Institut für Technologie

Eike Roswag-Klinge Technische Universität Berlin

Kristin Wellner Technische Universität Berlin

Alexander Passer Technische Universität Graz

Guillaume Habert ETH Zürich

Thomas Lützkendorf Karlsruher Institut für Technologie

Eike Roswag-Klinge Technische Universität Berlin

Nina Pawlicki Technische Universität Berlin

Susanne Rotter Technische Universität Berlin

Philipp Misselwitz Technische Universität Berlin

Petra von Both Karlsruher Institut für Technologie

Alexander Passer Technische Universität Graz

Guillaume Habert ETH Zürich

Kristin Wellner Technische Universität Berlin

Catherine de Wolf ETH Zürich

#### Organizing Committee

Technische Universität Berlin

Eike Roswag-Klinge

Nina Pawlicki

Kim Gundlach

Selina Schlez

Sinali Lal d Aram

Lisa Kolkowski

Laura Wetzel

#### Scientifc Committee Overview

Habert, Guillaume ETH Zürich

Hack, Norman Technische Universität Braunschweig

Hafner, Annette Ruhr-University Bochum

Hagemann, Anke Technische Universität Berlin

Hartmann, Timo Technische Universität Berlin

Hebel, Dirk Karlsruher Institut für Technologie

Heikkinen, Pekka Aalto-Yliopisto

Heisel, Felix Cornell University

Hemmerle, Claudia Technische Universität München

Hollberg, Alexander Chalmers Tekniska Högskola

Hoppe, Michaela Hochschule Bremen

Houlihan Wiberg Aoife, Anne-marie Ulster University

Hoxha, Endrit Technische Universität Graz

Hubmann, Georg Technische Universität Berlin

Huhnt, Wolfgang Technische Universität Berlin

Huovila, Pekka Sustainability Laboratory Oy

Klinge, Andrea ZRS Architekten Ingenieure

Klof, Harald Technische Universität Braunschweig

Knippers, Jan Universität Stuttgart

Kontovourkis, Odysseas University of Cyprus

Kurzrock, Björn-Martin Technische Universität Kaiserslautern

Kytzia, Susanne Ostschweizer Fachhochschule

La Magna, Riccardo Karlsruher Institut für Technologie

Lass, Wiebke Potsdam-Institut für Klimafolgenforschung

Longo, Sonia Universidad de Palermo

Lorch, Richard Buildings & Cities

Lupíšek, Antonín České vysoké učení technické v Praze

Lützkendorf, Thomas Karlsruher Institut für Technologie

Malaga, Katarina RISE Research Institutes of Sweden

#### Scientifc Committee Overview

Silvestre, José D. Universidade de Lisboa

Soust, Bernardette Universidad de Sevilla

Stollmann, Jörg Technische Universität Berlin

Tavares da Silva, Felipe Universidade Federal da Paraíba

Teufel, Patrick Technische Universiteit Eindhoven

Thuvander, Liane Chalmers Tekniska Högskola

Triantafyllidis, Georgios Technische Universität Graz

Truger, Barbara Technische Universität Graz

Volk, Rebekka Karlsruher Institut für Technologie

von Both, Petra Karlsruher Institut für Technologie

Wagner, Andreas Karlsruher Institut für Technologie

Walker, Pete University of Bath

Wellner, Kristin Technische Universität Berlin

Welp, Martin Hochschule für nachhaltige Entwicklung Eberswalde

Werner, Liss C. Florida International University

Wikstrom, Lindsey Columbia University GSAPP

Willmann, Anja Jade Hochschule

Wolf, Kerstin Technische Universität Berlin

Zea Escamilla, Edwin ETH Zürich

Ziegert, Christof ZRS Architekten Ingenieure

#### Scientif c Committee Student Conference

Scientific Sessions sbe22 berlin

#### ST Circularity I Circulor Moterial Systems

Surveying the Building Stock of Graz with Regard to a Circular Economy in the Construction Sector

B Hausegger 1 , M Raudaschl 1 , T Levak 1 , G Triantafyllidis 1 , E Dengg 1 , C Kurz 1 , R Riewe 1 , J Juhart 2 , A Gündera 1 , S Haingartner 1 , D Schlegl 1 , J Regl 2

1 Institute of Architecture Technology, Technische Universität Graz, Graz, Austria. 2 Institute of Technology and Testing of Construction Materials, Technische Universität Graz, Graz, Austria.

Keywords: City, Scenario Analysis, Circular Economy, Sustainable Construction, Data Analysis

Construction consumes about 40 % of resources globally. The switch to a circular economy model in the building industry can contribute to the reduction of use of resources, and lower the environmental impact by extending the life cycle of building components and materials. However, circular economy principles are not yet established in the buiding instustry, while at the same time the complexity and consequences of such a transition require further research. The objective of the exploratory study »City Remixed«, whose frst results are discussed in this paper, is to identify reuse and recycling potentials of Graz's building stock for the city of Graz, in order to initiate the transformation of the building sector of the city towards a circular economy. Considering the city of Graz and its surroundings in a reasonably short transport distance as a closed system, we started by quantifying the existing building stock in form of a digital 3D model as shown in this paper. In addition to the recording of the materials or construction elements present in buildings and infrastructure (networks) and quasi bound in them with regard to type of building material, quantity, condition and position in a geo-information system (»urban cadastre«), the expected future time

of availability of the material or construction element is also to be recorded digitally. In the future we will enrich the model with metadata, in order to enable the investigation of re-use and recycling potential of the components and materials, as well as to determine companies, manufacturers testing and certifcation institutes, that are necessary for these processes. Finally, we will develop renewal scenarios based on the existing building stock, as a result of possible component and material fows. From this process, we identify the felds of action, we settle decision-making bases and provide recommendations with regard to the transformation to a circular economy for different stakeholders, including the citizens. In this context, digital technologies allow the storage, recovery, management and update of large amounts of information, support the development of circular economy scenarios, which in turn ofer a simple way towards the re-use and recycle of materials in the building industry.

Circular Material Systems: Anticipating Whole-System Design in Architecture and Construction

G Hubmann 1 , V van Maaren 2

1 Technische Universität Berlin, Berlin, Germany. 2 C-Creators, The Netherlands.

Keywords: Circular Construction, Sustainable Architecture, Circular Economy, Built Environment, Whole-System Design

The construction sector is one of the most resource intense and environmentally damaging industries in the world. A promising approach to counteract this is to use principles of the circular economy (input reduction, reuse, and recycling) to ensure the continuity of value of a building's materials. Thus, we translated the learnings of an in-depth case study analysis, including four buildings and their construction processes into a defnition and framework for circular construction. We conceptualize buildings as circular systems that produce reusable components or biodegradable materials by practices operating across a building's lifecycle. These practices do not only include material and design aspects to close biological and technological loopholes, but

also immaterial practices such as knowledge and expertise, locality, management and skills, and information. We argue that these organizational aspects that go beyond the current state of the art are critical enablers for circularity in construction. This perspective is relevant for practitioners in the feld and allows for a new and holistic look at buildings as »waste generators« or, in a positive scenario, as »material depots«. Designing for recycling and reuse will require architects to build collaborations and knowledge across and beyond material value chains.

Rethinking Recurring Waste Flows: Creating Material Cycles by Identifying New Use Cases for Idle Materials J Scholz 1 , I Ordóñez 1,2, S Rotter 1

1 Department of Environmental Technology, Chair of Circular Economy and Recycling Technology, Technische Universität Berlin, Berlin, Germany. 2 ELISAVA, Barcelona School of Design and Engineering, Barcelona, Spain.

Keywords: Recurring Waste Flows, Idle Material Streams, Collaborative Material Workshops, Use Cases, Local Material Cycles

This article presents Collaborative Material Workshops (CMW), aimed at identifying new use cases for commercial waste materials waste materials, which are continuously being generated and have valuable technical properties. With the assumption that such materials habe a high re-use potential, they are defned here as idle material streams. The objective of CMW is to identify scalable and feasible applications for the re-use of idle material streams and to communicate those results to commercial adopters. In cooperation with a local secondary material initiative and a project-related NGO, TU Berlin researchers have investigated the idle materials »printing blankets« and »alumin-

ium composite panels« in two CMWs. Both materials combine valuable technical properties, a short use phase, and poor recyclability. The resulting two CMWs included 1) detailed background research, 2) physical material testing and 3) experimental CMW with material-related experts. With a special focus on the construction industry, the erticle discusses the barriers of identifying scalable and feasible new use cases for idle materials through the method of CMW.

Circularity and Sustainability in the Construction Value Chain

P Huovilaa 1 , N Westerholmb 2

1 Sustainability Laboratory, Helsinki, Finland. 2 Faculty of Built Environment, Tampere University, Tampere, Finland.

Keywords: Buildings and Construction, Business Models, Circular Economy, Construction Value Chain, Sustainability

This paper debates how circularity can contribute to value creation in the construction value chain. In traditional linear business models, value is ofen limited to fnancial value for the frm and customers. Here, value is seen more broadly considering a wider range of stakeholders, such as value chain partners, the environment, and the society. Findings from relevant literature and recent research projects are brought to transform linear cradle to grave processes to sustainable cradle to cradle ones. Circularity can contribute to sustainability in many ways: material recovery from existing buildings and reusing, recycling or even upcycling them into new ones and design

for disassembly that eases reuse and value retention. Findings indicate that circular economy has signifcant potential to create and maintain value in the construction value chain. Most of the decisions that afect value creation are done in the design stage, but it is strongly linked to the other stages and afected by business models, circularity platforms, and external infuencers, such as fnancing, client's requirements, regulations and incentives.

Assessing Circular Information Flow in Industrialized Construction: A Framework for Evaluating Data for Circular Construction J Berglund-Brown 1,2, F Kedir 1 , A Riabova 1 , D Hall 1

1 Chair of Innovative and Industrial Construction, ETH Zürich, Zürich, Schweiz. 2 Building Technology Program, Department of Architecture, Massachussetts Institute of Technology, Cambridge, USA.

Keywords: Building Firms, Literature Review and Survey, Circular Information Flow, Industrialized Construction Firms, Circular Construction, Circular Data

A circular economy ofers a solution for improving both the efciency and environmental impact of the built environment. As the construction industry transitions to a circular economy, adequate information fow is necessary to keep products in the value chain for as long as possible. Industrialized construction frms show high potential for a successful transition to a circular economy because of optimized information fow through the use of product platforms, the use of information communication technologies, and the integration of actors. However, there is no current framework to assess whether construction frms using industrialized construction methods have a circular information fow. In this research, four characteristics are identifed as main descriptors of a circular information fow framework: completeness, availability, accessibility, and incorporation of information into business strategy. Using the framework, industrialized construction frms are asked to self-assess their performance through pre-defned survey questions. The fndings from sixteen industrialized construction frms reveal the need for more complete data about recyclability potentials of products and unique

materials and product identifers, with 47 % of frms indicating they have insufcient information. The survey of companies also indicates a need for more feedback about the reuse, recycling, and remanufacturing phases to be available, with only 20 % of frms gathering feedback about reuse, 13 % about recycling, and 20 % about remanufacturing. The stakeholders with the most consistent access to information about design and materials of a project are the manufacturer, engineer, architect, and assemblers. 13 % of frms employed RFID tags. More accessibility of information is needed for actors outside of the frm. Additionally, only 13 % of frms implemented a take-back strategy, emphasizing the need for incorporating these business strategies within the frm. 17 % of frms, however, had CE in mind during strategic development, demonstrating the potential for CE adoption in the industry. Finally, the paper discusses future opportunities for circular information fow, such as employing blockchain technology.

Predicting Material Consumption in a Circular Economy Oriented Design Methodology for Pedestrian and Cycling Bridges

K Anastasiades 1 , A Audenaert 1 , J Blom 1

1

 University of Antwerp, Faculty of Applied Engineering, Energy and Materials in Infrastructure and Buildings (EMIB), 2020 Antwerp, Belgium.

Keywords: Circular Construction, Conceptual Design, Morphological Indicators, Structural Optimization, Material Consumption

A Circular Economy (CE) oriented design methodology for pedestrian and cycling bridges that takes the 4Rs of the CE – Reduce, Reuse, Recycle, Recover- as basis needs to be developed. The frst R, Reduce, is mostly neglected, even though it is the most important R in the CE. Nevertheless, a CE oriented design methodology also needs to consider and formalize Reduce. It is proposed to do this by measuring the material efciency of a structure. Therefore, a reference volume of material needs to be found. This paper proposes a methodology to predict the necessary amount of material needed for the bridge structure. The methodology takes the theory of the morphological indicators as basis. Morphological indicators are used in the conceptual design phase to fnd the most efcient structural typology and global dimensions. However, it was found that the volume indication that results from these morphological indicators is not realistic. The main reasons are that they consider a fully stressed state for each component, and they do not consider standard profle sections. Therefore, two correction curves are proposed to correct the volume obtained from the morphological indicators into a realistic one. The limitations of this study are that it only focuses on Warren truss bridges and only considers vertical service loads. Further research will have to focus on incorporating other types of trusses and other structural typologies like arched, suspension and cable-stayed bridges. In addition, more loads like wind and snow that can act on bridges need to be considered.

#### s.2 Circularity II – Circular Economy of the Building Sector

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Reconsidering the Assessment Method of Environmental Implications of Circular Economy in the Built Environment

#### S C Andersen 1, 2, M Birkved 2

1 Buildings & Environment, Danish Technological Institute, Gregersensvej, Denmark. 2 SDU Life Cycle Engineering, Department of Green Technology (IGT), University of Southern Denmark, Odense-M, Denmark.

Keywords: Built Environment Circular Economy, LCA as Decision Support, Prospective Scenario Development, Shared Socioeconomic Pathways

Are we capable of addressing environmental consequences on a societal scale of circular solutions for the built environment, or merely capable of addressing these impacts applying a narrow product/corporation perspective? Considering evaluations and quantifcations of envi-ronmental implications associated with implementations of Circular Economy (CE) design processes in the Built Environment, we postulate that these solutions necessitate decision-support tool-advancement, as CE does not allow for business-as-usual (BAU) assessments only. The BAU assessments of environmental impacts in the built environment, seem to paint a certain picture of the circularity paradigm. The question, however, is whether, by relying on simplifed assessments, we end up barely making it to the fnish line, very late, and risking loosing focus and creating sectoral burden-shifing. Application of LCA has created a paradoxical situation in the building industry. Gaining more experience in application of LCA, the industry steadily increases the complexity level of the questions to be addressed by LCA, thus increasing scale and complexity of systems to be assessed. Hence, currently, large systems such as CE models for the built environment, are ofen assessed in the same manner as we assess single buildings and building parts, despite

that CE models have a much higher potential to generate feedback efects, so that the system under assessment, changes due to the entity/service being assessed. The main question is hence, whether life cycle assessors operating within the built environment are aware of the challenges they are facing when answering questions regarding CE, and if these are addressed, assessment wise, in the /appropriate manner? Secondly, we need to consider how we facilitate assessment of systems at various physical and temporal scales in such a way that it becomes economically and technically feasible for the industry to address complex sustainability questions. This paper discusses possible future application potentials of LCA and propose consistent scenario defnition, and thus looks into the question: how come, that we assess almost all systems in a 'static' manner, while being completely aware of the fact that we live in a dynamic world? Are we, within LCA, addressing the need for improving the realism of the models that we derive in a sufcient and applicable manner?

How is the Construction Sector Addressing the Circular Economy? Lessons from Current Practices and Perceptions in Argentina

J Cohen 1 , L Rosado 1 , J Gil 1

1 Department of Architecture and Civil Engineering, Chalmers University of Technology, Gothenburg, Sweden.

Keywords: Construction and Demolition, Circular Economy, Barriers and Opportunities

The construction and demolition (C&D) sector mobilize a signifcant number of resources and at the same time is responsible for a large fraction of waste worldwide (40 %–60 %). Although, the environmental impact of these by-products is low, waste generated ends up in landflls, is downgraded and because of its volume it has become a priority at diferent governmental levels. In this context, the circular economy (CE) provides a set of strategies to improve efcient use of resources, thus reducing the environmental footprint of C&D. Most academic literature has focused on China, Europe, or the US, but knowledge about CE practices and perceptions in global south countries is scarce. To reduce this knowledge gap, this study focuses on Argentina and explores what are the perceptions, challenges, and opportunities for adopting CE strategies by the C&D sector. To achieve this goal, a survey was developed and distributed with support from the Argentinean Chamber of Construction (CAMARCO), among members of the chamber and other C&D relevant networks. The survey was carried out in the Autumn of 2021 and 88 C&D frms representing diferent size, longevity and business cycle responded. The results of the survey show that most of surveyed frms are trying to engage with the concept of CE. Secondly, a lack of digitalization and information are seen as important barriers to transition to CE. Finally, policy makers should focus on providing fnancial and tax incentives to secure a better environmental future.

Paving the Way Towards Circularity in the Building Sector: Empa's Sprint Unit as a Beacon of Swif and Circular Construction

E Kakkos 1 , R Hischier 1

1 Technology & Society Laboratory, Empa, St. Gallen, Switzerland.

Keywords: Sprint Unit, Life Cycle Assessment, Circular Economy, Sustainability Assessment

In order to achieve the CO₂ targets stipulated within the Paris Agreement, future buildings must be constructed in such a way, that their emission profle will be close to zero. In order to achieve this, a radical shif towards a circular construction manner which encompasses topics like material reuse (i.e., design for multiple lifecycles), design-for-disassembly (allowing for maximum recovery of materials and minimization of construction waste) must be promoted against today's conventional construction practices. Furthermore, the current COVID-19 pandemic has shown that buildings must be constructed in a more fexible manner, in order to be adaptable to changing needs as quickly as possible – including new types of needs. A transition to such a circular construction practice requires also new approaches for Life Cycle Assessment (LCA), taking into account issues such as the circularity or multiple life cycles of materials. Conventional LCA methods fail to deliver trustworthy results as they are designed to assess products and buildings that have only a single life cycle. In this context, a newly constructed unit,

set to be the embodiment of the circular construction principle that incorporates all the above-mentioned concepts in the form of a cluster of fexible ofce spaces, has been integrated into the research building NEST (Next Evolution in Sustainable Building Technologies) – a platform located at the Empa campus in Dübendorf (Switzerland), where novel building technologies can be tested and validated under realistic conditions. Its name: Sprint. In this paper, the environmental performance of Sprint is assessed through LCA, using three diferent approaches – the EN15804 method, the Product Environmental Footprint method and the Linear Degressive approach – with the latter two approaches considering the circularity of materials, while each one having an own, distinctive allocation rule for the split of the impacts between the current, the previous and the subsequent lifecycles.

The Socio-Spatial Efects of Circular Urban Systems

G Hubmann1

1 Technische Universität Berlin, Berlin, Germany.

Keywords: Sustainable Neighborhoods, Circular Economy, Climate Change, Infrastructure, Urban Political Ecology

This article shows what kind of urban spaces are produced by circular systems. The focus is on the socio-spatial dimension of closed material loops in two neighborhoods (e.g., reuse of grey water, recycling of waste, provision of renewable energy). Although the Circular Economy (CE) narrative is increasingly part of urban transformation policies, there are considerable implementation gaps in how regenerative or self-sufcient systems are operationalized in practice. I argue that the application of circularity principles in the urban context requires conceptual clarifcation to be useful for urban theory and practice. Therefore, I provide a political ecology perspective of circular urban systems by analyzing two cases: Block 6 in Berlin and Schoons-

chip in Amsterdam. I explain how such systems were established, who benefts from them, and what kind of socio-spatial conditions they produce. Methodologically, I use several qualitative research methods in the framework of a case study analysis. The results show that the incremental and publicly fnanced low-tech development of circular systems is socially compatible while privately funded high-tech developments result in stronger levels of sustainability but are reserved to a small exclusive group of people and provoke gentrifcation processes.

An Urban Hospital Based on the Principles of Circular Economy: The Case of Joseph Bracops Hospital

G Scialpi 1,2, J Declercq 1 , L Grisay 1 , D Perrotti 2

1 archipelago architects, Brussels, Belgium. 2 UCLouvain, Tournai, Belgium

Keywords: Hospital Building, Circularity Assessment, Healthcare, Circular Building, Reversible Building Design Protocol

The building industry has mainly focused on improving operational energy consumption to minimize the environmental impacts of buildings which are major sources of greenhouse gas emissions (GHG). However, considering the full life cycle of buildings, energy use and GHG emissions occur for reasons that extend beyond the operational phase and involve the embodied impacts of construction and disassembly. Circular building design can provide a holistic approach where the building's whole life cycle is considered in a manner consistent with circular economy principles, minimizing global material consumption, reducing waste and insuring a more circular building material stock. To date, research on the wide-scale adoption of circular design and construction strategies in public projects is still lacking. On this basis, the case study of the new Joseph Bracops hospital in Brussels shows that circular building design princi-

ples can be applied in the healthcare sector within the framework of a public tender. The project integrates circular economy principles at diferent scales (city, site, building, element), optimizes diferent material and energy fows and takes into account diferent time spans (short and long term). The study also ofers insight and guidance for future research into how the urban hospital of tomorrow will be a resilient public venue. Such a venue can enable a more comprehensive approach of health promotion, refected by the qualitative integration of circular economy principles, both with a social and technical focus, connected to the community and capable to mutate over time.

Keywords: Building Stock, Survey, Scanning, Lidar, Deconstruction, Reuse

ScanR: A Composite Building Scanning and Survey Method for the Evaluation of Materials and Reuse Potentials Prior to Demolition and Deconstruction

This paper introduces ScanR (Scan for Reuse), a composite method pairing quantitative and qualitative salvage and deconstruction surveying (S&D survey) with LiDAR and photogrammetry scanning in an efort to empower local municipalities and stakeholders in cataloging building materials prior to removal from site (in the case of either demolition or deconstruction), and enabling data collection and the generation of material databases to link local supply with demand – all in support of a shif from linear to circular economic models in construction. The speed of capturing large spaces through 3D scans and the ability to export such models into CAD sofware allows for a rapid assessment of surface and foor areas to calculate fnishing material quantities and other material content, but lacks metadata such as quality and potential hazards that are necessary for a potential deconstruction contractor. Furthermore, information on spaces inaccessible to scanning, such as wall cavities, are necessary to comprehensively assess a building's reuse potential. In supplementing scans with S&D surveys using accessible tools and sofware, these factors can be noted and referenced in relation to the space and 3D model, providing critical information to inform the harvest of materials and planning of the materials' next use cycles. In testing this method on a building slated for deconstruction, this paper demonstrates the advantages of each method of data collection and how one can be leveraged to support the other to further catalyze local eforts to divert material from waste streams.

Environmental and Economic Analysis of New Construction Techniques Reusing Existing Concrete Elements: Two Case Studies

C Küpfer 1 , M Bastien-Masse 1 , J Devènes 1 , C Fivet 1

1 Structural Xploration Lab, Ecole Polytechnique Fédérale de Lausanne (EPFL), Fribourg, Switzerland.

Keywords: Cast-in-Place Concrete, Reuse, Life-Cycle Analysis, Construction Cost, Circular Economy

As the most widely used construction material worldwide, concrete is the main cause of greenhouse gas emissions, material depletion, and waste generation by the construction industry. Typically, concrete waste is crushed and, at best, reclaimed into recycled aggregate or used as gravel. This process is energy-intensive and results in a reduction in material properties. In contrast, the direct reuse of concrete elements from obsolete structures ofers great potential for signifcantly reducing the environmental impact of new constructions. To be reused, concrete elements are carefully sawn out of soon-to-be-demolished buildings. Elements are then used without other major transformations for another service cycle in a new assembly. This paper analyzes two recent projects in Switzerland that showcase innovative applications of concrete reuse: a post-tensioned segmented

arch footbridge and a parking pavement. Both projects reuse blocks extracted from cast-in-place concrete buildings undergoing transformation or demolition. In this paper, environmental and economic analyzes provide a comprehensive understanding of the alleviations and costs involved. Results are compared to those of alternatives with conventional construction methods. The two projects reusing concrete globally showcase a drastically lower environmental impacts for comparable or higher construction costs, hence calling for future developments of such new circular construction strategies.

F Herrmann 1 , H Pürschel 1 , J Wörner 1 , J Blasius 1 , L Lahiri 1 , M Böhme 1 , V Hartmann 1

Sauerbruch Hutton / SHif

1

Restructure, Repurpose, Extend: Design Strategies for Futureoriented Building and for Strengthening the Potential of the Existing Building Fabric

Climate neutrality coupled with an overall positive ecological footprint is still a distant dream for new construction. The German building sector is directly and indirectly responsible for about 40 % of all German CO₂ emissions and has so far failed its CO₂ reduction goals. For the German building sector, the key to climate neutrality lies not only within new construction but in its existing building fabric. The embodied carbon of new construction needs to be reduced, as well as the amount of new construction itself. Hence the reuse of buildings and the extension of their life cycles is a crucial factor in reducing CO₂ emissions and resource

consumption. In this paper we present three of our projects (from the ofce Sauerbruch Hutton), highlighting not only the potentials but also the problems that planners face with existing buildings. Additionally, our project based LCA analysis showcases that retroftting can have a much smaller CO₂ footprint than a new building.

Current LCA Framework: Impact of Reuse and Reusability in Diferent Life Cycle Stages

E Douguet 1 , L Wastiels 1 , L Delem 1

1 Belgian Building Research Institute (BBRI-CSTC-WTCB), Brussels, Belgium.

Keywords: LCA Methodology, Reuse, Case Study, Module D

In the context of circular construction, the (potential) reuse of construction materials and building products is set forward as a general concept to reduce the environmental impact of buildings. But does this really lead to reduced impacts? A standardised framework to calculate the environmental impact of buildings over their life cycle is available through the European standards EN15804+A2 and EN15978 for life cycle analysis (LCA) in construction. The concept of reuse does however intrinsically focus on multiple use or life cycles. A correct quantifcation of the environmental impacts of reuse in buildings, requires a better understanding of the diferent mechanisms and issues at play. By means of critical assessment of the LCA methodology, in combination with a simplifed case study, this paper provides insights in how diferent reuse options for products are valorised (or not) when calculating the environmental impact. It is shown that the LCA standard EN15804+A2 allows to quantify the impact related to diferent concepts of reuse at the beginning or the end of the considered

life cycle. In general reused products will lead to larger environmental gains as the production stage (A1-A3) can be avoided. The environmental beneft related to the reusability of a product is typically refected in a smaller diference in the end-of-life (EOL) stage (C1-C4). Also the relevance of existing concepts, such as module D, is discussed for each of the considered reuse options. Results show that module D can provide insights in the future potential of reuse (at EOL) for virgin products, but that the numbers are difcult to interpret and even misleading for reuse products. The results and discussion show the limitations of the current LCA framework for these types of products and identify the need for the integration of additional concepts to correctly valorise the potential of reusable products using LCA.

Evaluating 'Reuse' in the Demolish or Reuse? The Balance Between Operational and Embodied Emissions in the Retroft of Commercial Buildings

D Abbey 1 , H Arbabi 1 , C Gillott 1 , W O C Ward 1 , D Densley Tingley 1

1 Department of Civil and Structural Engineering, University of Shefeld, UK.

Keywords: Embodied Carbon, Operational Energy, Whole Life Carbon, Retroft, Demolition

There are two clear options for reducing the emissions of poorly-performing buildings: refurbishment of the space to a higher standard or demolition and replacement with a better performing building. Non-residential buildings are subject to the latter of these options more than dwellings due to higher rates of ownership changes. This study assesses the carbon emissions of each of the above options for a poorly-performing retail building in Shefeld, UK. The embodied carbon and operational performance of each scenario are calculated to identify the most sustainable option over a 50 year lifespan. The scenario with the lowest emissions is found to be a retroft case study relying upon electricity as its sole fuel

source. The new build scenarios emitted signifcantly more carbon over the building's lifespan despite performing better operationally than the refurbishment scenario. It was also found that, due to the decarbonization of the national grid, relying on gas boilers instead of electric fuel sources would make carbon emissions approximately 2.5x bigger in the refurbishment model, despite being legal under UK building regulations.

GMIT and the Systematic Environmental Assessment of Secondary Materials I Ordóñez 1, 2, S Rotter 1 , J Scholz 1

1

 Department of Environmental Technology, Chair of Circular Economy and Recycling Technology, Technische Universität Berlin, Berlin, Germany. 2 ELISAVA, Barcelona School of Design and Engineering, Barcelona, Spain.

Keywords: Secondary Materials, Urban Resource Centres, Simplif ed LCA Integrated to a Digital Inventory Tool, Open Source, Idemat, Online Catalogue

This article reviews the development of a digital inventory tool developed specifcally for secondary material markets. Unlike other available inventory tools, this tool aimed at including environmental assessment features, that would allow warehouse managers to have an estimation of their environmental contribution associated to their sales performance without having to engage environmental experts regularly. The resulting open source sofware allows to keep an inventory of items available at the warehouse, export to an online shop and generate reports of the sales and environmental benefts of reusing some of

the secondary materials sold. This article explains how the tool was developed, how the simplifed LCA calculations were done and integrated to the tool, the difculties encountered when compromising ease of use with the need for reliable data to do the environmental calculations, and refects on the reliability and scalability of the developed tool.

## Building Stock 1-Refurbishment ond Retrofitting

Reno-DM: A Knowledge Model to Support the Decision-Making Process in the Context of Residential Building Renovation Projects

#### J A P Amorocho 1 , T Hartmann 1 , L C Ungureanu 2

1

 Technische Universität Berlin, Berlin, Germany. 2 DigitAEC matters, Founder/Head of Research and Innovation, Romania.

Keywords: Decision-Making, Building Renovation, Knowledge Representation, Ontology

The decision-making process to select solutions in residential building renovation projects is a complex task. These projects encounter rigid governance and ownership structures, participation of multiple stakeholders, diverse requirements, and a lack of consensus regarding methodologies and tools used within the decision-making process. Addressing some of these challenges requires a shared understanding of this domain. Therefore, this paper presents the Renovation-Decision-making (Reno-DM) model mapping key knowledge from the decision-making in renovation projects. It considers project characteristics, context information, building features, and their relation to aspects of the decision-making itself. The development of the Reno-DM

model relies on an existing decision-making representation and the extraction of new concepts from interviews with stakeholders taking part in renovation projects and related literature. The interviews are analyzed following an inductive content analysis approach. The Reno-DM model is developed in the form of an ontology. It provides a basis from which future knowledge management and reuse applications can be developed and deployed to support improvements in the decision-making process in the renovation feld.

Investigating the Role of Emissions Deriving From User Transport in Sustainable Refurbishment Strategies for Buildings Relying on Low-Carbon Energy

#### O Fahlstedt 1 , R A Bohne 1

1 Department of Civil and Environmental Engineering, Faculty of Engineering, Norwegian University of Science and Technology, Trondheim, Norway.

Keywords: Building Stock, Built Environment, Travel-Induced Emissions, Location, Institutional Buildings, Municipality

Refurbishing existing buildings constitutes a signifcant role in reducing emissions from the built environment. Their optimization simultaneously demands time to the urgency to fulfll the sustainable development goals 9, 11, 12, and 13. Therefore, actions taken at the municipal level are deterministic for future outcomes as many municipalities manage large building portfolios and thus hold signifcant mitigation potential. This paper investigates the role existing institutional buildings have for greenhouse gas abatement when the scope is expanded from building scale to include the urban environment. The aim is to determine the importance of considering the location of buildings when evaluating refurbishment strategies. There is a potential for a more signifcant reduction of emissions when including user transportation. The role of travel-induced emissions from users, visitors, and employees in institutional buildings is potentially more critical than refurbishment for buildings already operating on low-carbon energy. Parts of a previously

developed theoretical framework are tested to aid a Norwegian municipality in its emissions abatement strategy. The study assesses the carbon emissions deriving from refurbishment and the location of an institutional building. Inventory data from building, transport routes, and transport modes are assessed with a case study approach, while generic data derives from literature. The result indicates the importance of addressing locations of institutional buildings within the urban form rather than optimizing separate entities. Truncation errors can ofset the beneft of building optimization in areas dependent on low-carbon electricity if travel-induced emissions are omitted from the assessment. The framework reveals that it is better to build a new building at another location in some instances when transport-related emissions are reduced.

Building the Future Using the Existing Building Stock: The Environmental Potential of Reuse

L C M Eberhardt 1 , H Birgisdottir 1

1 Danish Building Research Institute/Aalborg University, Copenhagen, Denmark.

Keywords: Circular Economy (CE), Life Cycle Assessment (LCA), Reuse, Construction and Demolition Waste (C&DW), Embodied Greenhouse Gas Emission (EG)

Immense amounts of natural resources are consumed and processed by the construction sector every year resulting in a signifcant climate impact. In return, the resource and environmental value of these resources is lost due to the vast amounts of construction and demolition waste (C&DW) that is down-cycled. Thus, the potential of transitioning the construction sector from a linear to a circular economy (CE) is expected to be signifcant. In Denmark, C&DW make up 40 % of all waste. Although 88 % of the C&DW is recycled, only 36 % is upcycled (i.e., recycled with an equal or higher quality than the original resource), while 52 % is down-cycled (e.g., crushed for road flling). More recently interest in direct reuse has increased, as a better way of exploiting the remaining technical service life of the materials and retaining the inherent value of the materials and avoiding environmentally heavy material processing. In coming years, a large number of homes on Denmark's 'ghetto list' (i.e., socio-economically disadvantaged residential areas) corresponding

to 1,360,300 m2 are to be demolished. At the same time, a large number of new buildings is to be built in the same afected areas. The Resource Block project seeks scalable reuse solutions that can link the large amount of resources in the existing buildings to be demolished with the need for resources to build the new buildings in these areas. On the basis of a life cycle assessment (LCA), the paper at hand assesses the environmental beneft of the reuse solutions found from the Resource Block project. The results show that reuse of these elements may on average potentially save 49 % of the new buildings' greenhouse gas emissions compared to building solely with virgin materials depending on the availability and degree of reuse and which types of virgin materials the reuse is combined with.

Drivers and Challenges for Implementing Sustainability-Oriented Upgrading in Social Housing in Brazil

#### L H S C Vasconcellos 1 , D C C Knatz Kowaltowski 1 , V Gomes 1

1

 University of Campinas, School of Civil Engineering, Architecture and Urbanism, Cidade Universitária Zeferino, Campinas, São Paulo, Brazil.

Keywords: Social Housing, Sustainability, Upgrading, Drivers, Challenges, Prioritization

Social housing (SH) development is, in general, triggered by policies and regulations, which stimulate interventions, create fnancing mechanisms, and designate agents conducive to retroft processes. European directives for energy efciency and the recent call for a »retroft wave« have an evident infuence. In Brazil, delivery and management of SH are based on the public ofer of housing units and their immediate ownership transfer. National or state housing agencies are responsible for basic maintenance for fve years, but other post-delivery interventions depend exclusively on the efort and expenses of the occupant. SH budgets leave little or no margin for extra spending and bringing SH to international sustainability standards is not yet mandatory. The issues that arise to implement upgrading in this context are therefore related to the following questions: What are the prioritized actions in upgrading processes? What type of fnancing would be required or is available? What is the project execution model and who are the stakeholders involved? This article focuses on the issue of prioritization of actions for upgrading SH. A systematic literature review examined reported sustainability-related housing improvements. A critical review of a Brazilian building label and two international sustainability assessment methods then supported ranking the upgrading actions according to the relevance assigned in their respective contexts. Finally, a panel of construction professionals provided insights regarding the technical feasibility and intrusiveness of their implementation in both single- and multi-family SH projects. Findings show that minor upgrading actions, such as changing hydraulic or electrical fxtures or landscaping, usually do not cost more than implementing them from the beginning and are equally applicable to single- and multi-family SH projects. But, when high-level (deep upgrading) interventions are on the table, costs rapidly increase due to the need to substantially change existing systems or supporting structures, which makes them ofen fnancially and/or technically unfeasible.

New Angles for Adaptive Building Reuse Research

E C Bowyer 1 , V Stephenson 1 , W Hawkins 1 , T Ibell 1

1 Department of Architecture and Civil Engineering, University of Bath, Bath, UK.

Keywords: Suggesting New Approaches for Adaptive Building Reuse Research Through Literature Review and Evaluation, Embodied Carbon, Building Lifespans, Sustainability

This paper seeks to establish the current state of research into adaptive building reuse with the view to highlighting new approaches and opportunities for expanding the collective knowledge on this subject. This approach focuses on appraisal and evaluation of current methods by looking through a structural engineering lens and

considering the most benefcial options in terms of reducing additional embodied carbon intensity in our built environment.

# Building stoc Refurbishment ono Retrofitting

Exploring Longterm Building Stock Strategies in Switzerland in Line With IPCC Carbon Budgets

Y D Priore 1,2, T Jusselme 1 , G Habert 2

1 Energy Institute, University of Applied Science of Western Switzerland (HEIA-FR, HES-SO), Fribourg, Switzerland. 2 Chair of Sustainable Construction, ETH Zürich, Zürich, Switzerland.

Keywords: Carbon Budgets, Building Stock, Carbon Targets, Emissions, Mitigation

Stringent limits and reduction strategies paths on greenhouse gas (GHG) emissions are being defned at diferent levels for long-term temperature stabilization. Given the nearly linear relationship between warming and cumulative net emissions, a carbon budget approach is required to limit global warming, as stated by the IPCC. In this setting, the built environment, as a cross-sectorial and transnational area of activity, plays a crucial role in today's carbon emissions and future reduction potentials. Previous research showed the need for efective and aligned carbon-targets to support and guide all actors in the construction sector towards these challenging global goals. In this context, previous research compared top-down derived carbon budgets for the Swiss built environment with a preliminary estimation of future cumulative emissions of the sector. Findings showed the misalignment of current best practices and the signifcant magnitude of efort that would be required to comply with such objectives. Nevertheless, limitations in the preliminary work emerged, such as the lack of dynamicity of the parameters included in the model restricting the representativity of its results. The current paper brings further this previous work by integrating the dynamic evolution of the energy supply, the materials' production, and the renovation rate. Results are then presented by means of a parallel coordinate interactive graph. This interactive component allows the parametric exploration of the compliance with limited global budgets by varying the input parameters. This way, the infuence of macro-level strategies to decarbonize the Swiss building stock can easily be visualized with reference to the IPCC carbon budgets. Ultimately, the available interactive tool might support policy makers in decisions taken at the building stock level.

Life Cycle GHG Emissions of the Austrian Building Stock: A Combined Bottom-Up and Top-Down Approach

#### B Truger 1 , S Nabernegg 2 , T Lackner 2 , M Röck 1,3, N Alaux 1 , E Hoxha 1,4, M Ruschi Mendes Saade 1 , A Passer 1

1 Technische Universität Graz, Institute of Structural Design, Working Group Sustainable Construction, Graz, Austria. 2 University of Graz, Wegener Center for Climate and Global Change, Graz, Austria. 3 KU Leuven, Design and Engineering of Construction and Architecture, Leuven (Arenberg), Belgium. 4 Aalborg University, Department of the Built Environment, Copenhagen SW, Denmark.

Keywords: Building Related Emissions, Life Cycle Assessment, Input-Output Based LCA, Process-Based LCA, Building Stock

Construction and operation of buildings are responsible for 37 % of global greenhouse gas (GHG) emissions. In contrast, the Austria's National Inventory Report attributes a mere 10 % of national emissions to buildings – including only direct operational emissions of residential and service sector buildings. This narrow defnition of the buildings sector neglects important environmental hotspots attributable to building-related life cycle emissions and calls for a comprehensive analysis of GHG emissions of Austrian buildings. In this study, we assess annual building related GHG emissions for the Austrian building stock from a full life cycle perspective (i.e., including operational and embodied emissions). For embodied emissions, we model emissions using both a process-based and an input-output based life cycle assessment (LCA) approach. Building LCA case studies and statistical building stock data are used to estimate embodied emissions from a bottom-up perspective, which are complemented by estimated emissions from the input-output based LCA approach. Our work illustrates the importance of adopting a life-cycle perspective on building-related emissions to inform the diferent stakeholders and advance climate action in the built environment. While both

the chosen system boundaries and methods signifcantly determine the results, we argue that emission reduction measures should be based on a comprehensive system boundary of building-related emissions to contribute towards the achievement of a climate-neutral built environment and the stringent climate targets. By adding indirect emissions and non-residential buildings to the ofcially reported building emissions, the operational emissions alone increase by a factor of 2.4. As expected, the process-based LCA yields lower embodied emissions than the input-output based approach. Depending on the method, they can be responsible for up to 40 % of total buildings related emissions. Summing up, total buildings related emissions rise by a factor of 3 to 4 when extending the system boundaries to comprise the whole area of action buildings, and go from 7 Mt CO₂-eq/a (direct operational emissions, 10 % of national emissions), to 22-31 Mt CO₂-eq/a for the case of Austria.

Enhanced Productivity for the Future of Retroftting

M Defner 1 , M Dorresteijn 1 , B van Elven 1 , H Koene 1 , R Laterveer 1 , M van Os 1 , M Smilde 1 . T Topper 1

1 Utrecht University of Applied Sciences, Utrecht, The Netherlands.

Keywords: Productivity in Construction, Roof Retroftting, Panel Insulation, Process Improvement

With the growing efects of climate change, it has become of great importance to reduce emissions from the building stock. Climate friendly retroftting of dwellings has emerged as an important role since then. Based on a case study in the Netherlands and scientifc research on the associated processes, it is concluded that the state of the current retroftting process is not productive enough to meet European climate goals. To satisfy the increasing need for retroftting, the Axiomatic Design Method is used to track down the key fndings to improve the output of the retroftting process from a holistic perspective. The aim of the research is to contribute to increase the current output of 50.000 residential retrofts per year by 300 % for the Dutch construction industry. The results give op-

portunities for improvements that should be made within the process, product, and regulations in the industry. The elimination of manual labor in roof renovation is the fnding that has the greatest impact on process productivity. In addition, the changeover of the process has an impact, whereby scafolding, fall protection and weather no longer have an infuence or are no longer required. It can be stated that efciency could be signifcantly increased with low manual labor roof retroftting.

Comparison of Building Thermography Approaches Using Terrestrial and Aerial Thermographic Images

Z Mayer 1,2, A Epperlein 1 , R Volk 1 , E Vollmer 1 , F Schultmann 1

1 Karlsruher Institut für Technologie (KIT), Institute for Industrial Production (IIP), Karlsruhe, Germany.

Keywords: Building, Digitalization, Life Cycle Assessment, LCA Tools

Thermography is commonly used for auditing buildings. Classical manual terrestrial thermography records images of individual buildings at a short distance. When auditing a large number of buildings (e.g., whole city districts) this approach reaches its limits. Using drones with thermographic cameras allows images to be recorded automatically from diferent angles, with faster speed and without violating property rights. However, an airborne camera has a signifcantly greater distance and more varied angles to a building compared to terrestrial thermography. To investigate the infuence of these factors for building auditing, we perform a study evaluating seven diferent drone settings of varying fight speed, angle, and altitude. A comparison is drawn to manually

recorded terrestrial thermographic images. While we fnd that a fight speed between 1m/s and 3m/s does not infuence the thermographic quality, high fight altitudes and steep viewing angles lead to a signifcant reduction of visible details, contrast, and to falsifed temperatures. A fight altitude of 12 m over buildings is found to be the most suitable for the qualitative and quantitative analysis of roofops and a qualitative analysis of façades. A fight altitude of 42 m over buildings can only be used for qualitative audits with little detail.

BTPFlux: A Building Material Flow Analysis Model to Enhance the Urban Metabolism on French Territories

#### E Sorin 1 , R Tirado 1 , E Gully 1 , M Louërat 1 , S Laurenceau 1

1 University of Stuttgart, Institute for Acoustics and Building Physics, Stuttgart, Germany. 1 Scientifc and Technical Centre for Buildings (CSTB), University Paris-Est, France.

Keywords: Building Stock, Material-Flow Analysis, Construction Sector, Circular Economy, Material Building Stock

Worldwide, the construction sector is the principal consumer of raw resources (50 % of the natural resources) and the leading producer of solid waste (2.2 billion tons per year). Because of their quantity and their potential for development, construction wastes constitute a catalyst for establishing strategies and action programs aimed at making the management of resources circular at several territorial scales. Performing these strategies needs a detailed and structured knowledge of fows. In this context, the CSTB has developed a macro-component bottom-up-based model: BTPFlux, that aims to characterize the materiality of the building stock and the associated demolition, and renovation waste fows. A national database with generic information for every building on the metropolitan French territory was used. This database gathers information such as the surface, the typology, or the year of construction of the buildings and is then linked with a specifc database characterizing existing construction products. This method provides a detailed characterization of the building material stock available on the French metropolitan territory. So, the environmental impacts, the treatment costs, and the valorization potentials can be estimated by implementing diferent management scenarios for each category of waste assessed. The model was already successfully applied to the »Ile de France« region and can be replicated to any other French territory. The results will allow the stakeholders to better understand the materiality of their territory, giving them the possibility of making optimal decisions to implement the reuse and recycling of secondary resources. However, some improvements can still be made in the description levels of macrocomponents or in the description of infrastructures that BTPFlux does not currently model.

#### s.6 Buildings – Urban Timber Construction

102

Fringe Timber: Informing Regional Mass Timber Urban Environments with Biodiverse Forests

L M Wikstrom 1 , C Z Yu 1

1 Columbia University Graduate School of Architecture, Planning and Preservation, New York City, United States of America.

Keywords: Mass Timber, Biodiversity, Resource Management, Case Studies, Renewable Materials

Trees present a vast array of performance in density, growth speed, height, fbre strength, and rates of carbon absorption. This paper begins by exploring how biodiverse mass timber is not only a way to support an emerging pluralist point of view about the forest, but also to improve the health conditions of the most vulnerable and those who have experienced the pollution of mineral-based materials for generations. This symbiotic relationship between forests and urban environments incentivizes better care of forests to meet a range of tree species' needs. In the project Fringe Timber, a biodiverse supply of mass timber

informs regional mass timber urban environments and supports the role of resource pooling in reducing our collective carbon footprint. Using three case studies in New York City, Denver, and Tulsa, this paper posits city-specifc, species-driven supply chains beyond sofwoods for mass timber, including hardwoods and hybrids, to support the appropriate scale and speed for urban development.

Climate Impacts of Wood/Timber as a Building Material – Investigated on Three Urban Quarters in Germany (CIW)

E Roswag-Klinge1,2, E Neumann2 , A Klinge2

1 Technische Universität Berlin, Natural Building Lab, Berlin, Germany. 2 ZRS Architekten Ingenieure, Berlin, Germany.

Keywords: Climate Impacts of Wood/ Timber as a Building Material, Life Cycle Assessment, Timber Construction, Carbon Neutral Buildings, LCA, Timber-Quarters/ Holzbauquartiere

Due to the current discussion about the shortage of resources and the excess of greenhouse gas emissions, timber construction is experiencing a renaissance in Germany. As a renewable resource, wood can replace emission-intensive building materials and, if lef long-term in the construction, lead to negative balances, i.e., carbon sinks at the construction phase (LCA phase A1-A3). This means that more carbon could be stored in the construction than is emitted during production. This study analyzes diferent buildings ranging from row houses to high-rise buildings that are envisioned as envisioned as envisioned as envisioned as envisioned as timber construction of three so called timber-quarters (Holzbauquartiere). For all buildings, the current design/ construction, a conventional as well as a timber+ construction (maximum possible timber use in construction) variant have been evaluated. The calculations were conducted with eLCA the LCA tool of the Bewertungssystem Nachhaltiges Bauen (BNB) (German Green Building System) and the data sets of the German ÖKOBAUDAT[11]. The results are given per m2 gross foor area per user, per building and per neighborhood. The investigations show the importance of the material choice regarding the climate gas emissions of the buildings and how large the proportion of wood must be in order to design the building envelope (KG 300 (cost group for architectural elements) in a climate gas neutral way. Planning parameters for a climate gas neutral design and construction of buildings are derived from the analysis.

CircularWOOD – Towards Circularity in Timber Construction in the German Context

#### S Schuster 1 , S Geier 2

1 Technical University of Munich, TUM School of Engineering and Design, Chair of Architecture and Timber Construction, Munich, Germany. 2 Lucerne University of Applied Sciences and Arts, Competence Center Typology & Planning in Architecture (CCTP), Horw, Switzlerland.

Keywords: Timber Construction, Analysis, Circular Economy, Prefabrication, Cascade utilization

The circular economy can pave the way to achieve ambitious sustainability goals. A major perpetrator of resource and material waste is the building sector. A lot of research results already provide innovative technologies and solutions for circular construction. However, what many of the circular economy initiatives in the construction sector have in common, is a certain malaise in moving from pilot projects with high individual engagement to actions on a larger scale. Prefabricated timber construction is one of the most promising key technologies towards a more resource efcient Europe. Despite this potential, downcycling or an early thermic utilization is common practice. Valuable resources are wasted and already captured CO₂ is released. The research project circularWOOD aims to provide a better understanding for potentials and barriers in a frst step. This paper outlines frst fndings. Prefabrica-

tion and element design facilitate circular construction approaches. The context in which stakeholder implement circular construction approaches is widened. A wide range of economic and ecological aspects is supplemented with cultural, political, and regulatory conditions. Under the premise of reuse with a minimum of necessary adaptation, structural aspects are evaluated. The results show a current concentration on new construction with easy-to-implement design approaches. Further eforts towards strategies for the reuse of existing construction and experiences to facilitate the difusion within the timber construction sector are required.

Benef ts of Wooden Structure Reuse: The Case of an Austrian Building

#### E Hoxha 1,3, B Soust-Verdaguer 2 , M Scherz 3 , A Passer 3

1 Department of the Built Environment, Aalborg University, Denmark. 2 Instituto Universitario de Arquitectura y Ciencias de la Construcción, Escuela Técnica Superior de Arquitectura, Universidad de Sevilla, Spain. 3 Working Group Sustainable Construction, Institute of Structural Design, Technische Universität Graz, Graz, Austria.

Keywords: Wooden Construction, Life Cycle Assessment, Circular Economy, Material Flow Analysis, Multi Cycling

The building sector is responsible for 39 % of greenhouse gas (GHG) emissions; thus, it has a signifcant amount of potential to reduce the efects of climate change. Several active- and passive solutions and strategies have been developed and proposed in the literature. Among them, wood is highlighted as a promising solution to minimize GHG from buildings. However, the benefts, especially in the circular economy, are not fully evaluated due to methodological choices. Motivated by this knowledge gap, this article aims to evaluate the benefts of wood reuse compared to traditional building construction solutions. For this purpose, we have calculated the environmental impacts of a building situated in Graz, Austria. Four diferent scenarios are considered. The frst scenario is a fully reinforced concrete building. The second scenario is a structural beam-column made from reinforced concrete with walls made of concrete blocks. The third scenario is a beam-column made from reinforced concrete with external walls based on clay blocks. Finally, the last scenario is a full wooden building. Following the standardized life cycle assessment (LCA) method, global warming potential (GWP) is calculated through a 0/0 approach. These evaluations were made possible by correlating the impacts released from producing wooden elements and the uptake of biogenic carbon from the forest. Without considering the possibility of material reuse, the wooden structure has a 5  % lower GWP value than the reinforced concrete building. Comparatively, the other building scenarios have almost similar impacts as the building in reinforced concrete. In the case of material reuse, the wooden structure building shows potential to develop projects with 44 % less environmental impact.

## s.7 Sufficiency

11

Management, Bauhaus-Universität Weimar, Weimar, Designing Sustainable Germany. Oce Spaces: How to Combine Workspace Characteristics With Sufciency Strategies

#### R Fauth 1 , M Pieper 1, 2

1 CG Elementum AG, Leipzig, Germany. 2 Faculty of Civil Engineering, Chair of Construction Engineering and

Keywords: Sufciency in Construction, Conceptual Framework, Sustainable Workspaces, Sufciency Principles, Development Strategies

Contemporary workspace and ofce concepts are part of many major commercial real estate projects and have been continuously developed over many years. With a rising awareness for sustainable development, workspace and ofce concepts are increasingly being considered in terms of their environmental performance. Sustainable design strategies therefore traditionally diferentiate between efciency, consistency, and sufciency, whereas the latter approach is the least explored in the construction industry. Sufciency can be described by a user behavior characterized by frugality and modesty, as opposed to wasteful consumption. Moreover, the strategy of sufciency is linked to a high and critical awareness of using natural resources and environmental impacts which also afects the built environment. The aim of this paper is therefore to combine these two subject areas in a structured way and derive potentials for the sufcient development of ofce concepts.

Based on a literature review in the feld of workspace design and fexible workplace management, design features of ofce spaces are conceived and compiled according to planning aspects in ofce concepts based on employee needs. Another literature review in the feld of sufciency in the

building sector provides the corresponding structure for the considered sufciency strategies. Sufciency measures follow recurring principles for the reduction of resource consumption. Essential principles of impact are identifed and presented in this paper. The investigated topic areas are compiled together in a logical model based on a developed mapping framework. This forms the basis for defning sufcient measures that can be derived to sufciency strategies in the project development of ofce buildings. The basis of all measures is to strive for a minimum level of resource consumption that is necessary to satisfy the needs of the users and that is considered valuable by them, following the basic idea of the sufciency approach. The results are validated using an ofce building in the planning stage. The paper leads to a common understanding and structuring of design features of future ofce spaces and their environmental impact. Furthermore, the approach provides guidance for concepts on how design features can be considered regarding sufciency strategies.

Sufciency as a Criterion for Sustainability Assessment

Annika Hock 1 , Juliane Jäger 1 , Andreas Rietz 1

 Federal Institute for Research on Building, Urban Afairs and Spatial Development (BBSR), Division Sustainable Building, Berlin, Germany.

1

Keywords: Sustainability Dimensions for Sufciency Measurement in Sustainability Assessment for Buildings, Sufciency, Sustainability Assessment, New European Bauhaus

Key instruments of the German sustainability strategy for federal buildings are the »Guideline for Sustainable Building« (LFNB) and the 'Assessment System for Sustainable Building' (BNB). Based on the three pillars of sustainability (ecological, economic and social dimensions) and expanded by building related cross-sections (technical, process and location), sustainability research is opposing sustainability strategies of consistency, efciency, resilience and in particular sufciency. Likewise, the New European Bauhaus (NEB), initiated by the EU-Commission in 2021, acknowledges the recognition of the fnite nature of resources and introduces the term sufciency as a relevant aspect. This requires a consistent rethinking of the way we plan, construct, and operate buildings. However, sufciency is ofen not or only partially addressed in sustainability assessments. The available research points

towards a necessity to rethink the classic pillars of sustainability. Sufciency should not be seen as relinquishment, but the basis for a successful efciency and consistency implementation.

Up to now, the environmental impacts of buildings have usually been determined and evaluated as area-related parameters, omitting saving efects of area reduction. This paper proposes a reconsideration of reference values and evaluates possibilities for a BNB system integration of sufciency criteria. The investigation does not aim to determine specifc valuation criteria, but outlines possible locations for adaptation or inclusion within the pillars of sustainability.

Mitigating Climate Change Through Healthy Discomfort S Clark Koth 1 , Bilge Kobas 1 , K Bausch 1 , T Auer 1

1 Lehrstuhl für Gebäudetechnologie und Klimagerechtes Bauen, Technische Universität München, München, Germany.

Keywords: Thermal Comfort, Health, Mechanical Ventilation

Amid the climate change and the worldwide catastrophes, witnessed on a daily basis, we fnd ourselves in a time in which we need to start justifying any recourse and energy consumption, at least of which is not truly renewable. While the outside temperatures become more extreme, the inside environment becomes more relevant. The way we design and operate our buildings is directly infuenced by current building standards and as we spend almost all our time indoors, our comfort, wellbeing and health are crucially afected by such. The last fve decades have seen many approaches in establishing guidelines for a comfortable indoor environment. But while current standards favor the narrow temperature ranges

of static homogeneous environments, they have been criticized for their high energy consumption and long-term health implications. The paper compares a typical ofce space with mechanical cooling with that of a passive strategy, by evaluating the energy consumption and health over comfort. The results show a 64 % cooling potential within the mechanically cooled scenario as well as the passive strategy complying to standard without any cooling energy.

Ef ect of Neighborhood Courtyard Design on the Outdoor Thermal Comfort in a Tropical City

#### H N D Ngo 1, 2, E Motoasca 3 , A Versele 1 , H C Pham 2 , H Breesch 1

1 Research group Building Physics and Sustainable Design, KU Leuven Ghent Technology Campus, Ghent, Belgium. 2 Faculty of Architecture and Urban planning, Hanoi University of Civil Engineering, Hanoi, Vietnam. 3 VITO NV, Mol, Belgium.

Keywords: Outdoor Thermal Comfort, ENVI-Met Simulation, Courtyard Landscape, Tree Coverage, Shading

In the tropical city of Ha Tinh (Vietnam), the number of new developed neighborhoods in the courtyard layout is increasing while the city is experiencing annual severe heat stress. The paper quantitatively analyzes, by means of ENVI-Met simulation, the effect of neighborhood courtyard landscape on the outdoor thermal comfort (OTC) in the tropical city of Ha Tinh (Vietnam). A sample 9-ha residential block was at frst experimentally confgured with four scenarios of courtyard, including (1) bare grass and perimetry location of high plants, (2) grass ground, fully occupied high trees, (3) water body and surrounding location of high plants, and (4) mixed ground surfaces of water, hard pavement and grass, and partly occupied high trees. The adding of tree canopies to the entire courtyard, consequently sufcient shades, as in case 2, contributes to the better OTC among the chosen scenarios by triggering the reduction of mean radiant temperature (Tmrt) (2.9oC) and physiological equivalent temperature (PET) (3.5oC) at the hottest hours as compared to the original confguration (case 1) during

the summer days. Application of perimetry plants with either water (case 1) or bare grass (case 3) results in higher PET though full occupation of water body lowers the air temperature by roughly 1oC. The limited impact on OTC of local water body is counter-intuitive, yet important result to the practice of urban design. The worst OTC was observed in case 4 where almost half of the garden was sun-exposed and intended for hard-paved playground and water body. Increasing shades against solar radiation is the most important measure to deal with intensive heat problem. The study is an essential part of translating academic knowledge on urban climate into interventions on urban design for better climate resilience of neighborhoods in Vietnam and by extend in other tropical countries.

#### s.8 Critical Digitalization

116

Measuring the Cityscape: A Pipeline from Street-Level Capture to Urban Quantif cation

W O C Ward 1 , M Dai 1 , H Arbabi 1 , Y Sun 1 , D Densley Tingley 1 , M Mayf eld 1

1 Department of Civil and Structural Engineering, The University of Shef eld, Western Bank, Shef eld, UK.

Keywords: Building Stock, 3D modelling, Street-Level Capture, Computer Vision

Any solution to achieving climate targets must be performed at scale. Data driven methods allow expert modeling to be emulated over a large scope. In the UK, there are nearly 30 million residential properties, contributing to over 30 % of the national energy consumption. As part of the UK Government's requirement to meet net-zero emissions by 2050, retroftting residential buildings forms a signifcant part of the national strategy. This work addresses the problem of identifying, characterising

and quantifying urban features at scale. A pipeline incorporating photogrammetry, automatic labelling using machine learning, and 3-D geometry has been developed to automatically reconstruct and extract dimensional and spatial features of a building from street-level mobile sensing.

Piezoelectric Textile Facade for the Energy Supply of Active Sensor Technology With Regard to Data Management for Circular Economy in Building Construction

M Raudaschl 1 , T Levak 1 , R Riewe 1 , G Triantafyllidis 1 , E Drnda 1 , S Popek 1 , D Schlegl 1 , D Funke-Kaiser 2 , A Lund 3

1 Institute of Architecture Technology, Technische Universität Graz, Austria. 2 Laboratory for Structural Engineering, Technische Universität Graz, Austria. 3 Department of Polymers, Fibers and Composites, Fiber Development, RISE Research Institutes of Sweden, Mölndal, Sweden.

Keywords: Facade System, Concept Development and Tests, Circular Economy, Construction Technology, Piezo Technology

The high GWP potential of construction requires a holistic approach such as circular economy. Currently, common joining, construction and planning practices result in heterogeneous assemblies of diferent components that are difcult to deconstruct. Furthermore, there is currently little information and data on building components used and the climatic impacts on them. In this context and with the intention of recording long-term (circular) processes in construction, the Piezo-Klett basic research project (FFG no. 879459) funded by the Austrian Research Promotion Agency (FFG) deals with the energy supply of active sensor technology in construction by combining the hook and loop fastener with piezoelectric components. The aim is to open new perspectives on sustainable

energy production systems by transforming buildings into energy carriers and generators, analogous to a »battery«. To this purpose, the result presented in this conference paper is a description of the constructive structure (climatic impacts, construction, piezo technology) of a »Piezoelectric Textile Facade«, as well as test results on piezo tapes. This opens new possibilities in the context of the application of hook-andloop fasteners, the energy supply of active sensor technologies as well as in the feld of data acquisition and data management.

Deep Multimodal Learning for Residential Building Energy Prediction

#### Y Sheng 1 , W OC Ward 1 , H Arbabi 1 , M Álvarez 2 , M Mayfeld 1

1 Department of Civil and Structural Engineering, The University of Shefeld, UK. 2 Department of Computer Science, University of Manchester, Manchester, UK.

Keywords: Residential Building Energy, Deep Multimodal Learning, EPC, Google Street View

The residential sector has become the second-largest energy consumer since 1987 in the UK. Approximately 24 million existing dwellings in England made up over 32 % of the overall energy consumption in 2020. A robust understanding of existing buildings' energy performance is therefore critical in guiding proper home retroft measures to accelerate towards meeting the UK's climate targets. A substantial number of predictions at a city scale rely on available data, e.g., Energy Performance Certifcates (EPCs) and GIS products, to develop statistical and machine learning models to estimate energy consumption. However, issues with existing data are not negligible. This work adopted the idea of deep multimodal learning to study the potential for using Google Street View (GSV) images as an additional input for residential building energy prediction. 20,031 GSV images of 5,933 residential buildings in central Barnsley, UK, have been selected for a case study. All images were pre-processed using a state-ofthe-art object detection algorithm to minimize the noise caused by other elements

that may appear nearby. Building specifcations that cannot be easily determined by the appearance are extracted from existing EPC information as text-based inputs for prediction. A multimodal model was designed to jointly take images and texts as inputs. These inputs are frst propagated through a convolutional neural network and multi-layer perceptron, respectively, before being combined into a connected network for fnal energy prediction. The multi-input model was trained and tested on the case study area and predicted an annual energy consumption with a mean absolute diference of 0.01kWh/m2 per annum on average compared with what is recorded in the EPC. The diference between the predicted results and the EPC may also provide some hints on the bias the certifcates potentially contain.

Suggestions for Solution Space Exploration in the Early Stage of Architectural Design Based on a Literature Review

#### J Li 1,2, X Bi 1 , W Yang 1

1 School of Architecture, Tianjin University, Tianjin, China. 2 Centre for Real Estate, Chair for Sustainable Management of Housing and Real Estate, Karlsruher Institut für Technologie , Karlsruhe, Germany.

Keywords: Buildings, Early Design, Design Space, Decision Support, Interactive Exploration

Early design decisions have higher potential to infuence building performance compared with the decisions made at later design stages. Performance simulation and optimization algorithms have been integrated to assist early design in reducing carbon emissions, improving indoor thermal comfort, etc. However, early decision making within a limited time frame is still challenging due to the large number of design options, the lack of decision-making guidance, and the trade-ofs among various requirements. Selecting appropriate methods to explore design space is the key to fnd an ideal solution. This paper reviewed the challenges and identifed the key questions to access the ability of existing decision-making methods to cope with diferent challenges. It is concluded that the interactive exploration of design space could be more

efective and efcient by (1) combining the surrogate models and the automated optimization algorithms to improve the efciency of the building performance calculation and the optimal design space position; and by (2) extending the optimal design space to increase the solution diversity, and (3) fltering the near optimal design space with consideration of the stakeholders' preferences and values. Further integration of tools for building performance simulation, diversity description and decision - making guidance is needed to support the decision-making process.

Stochastic Solar Irradiance from Deep Generative Networks and their Application in BIPV Design

Y Zhang 1 , C Waibel 1 , A Schlüter 1

1 Chair of Architecture and Building Systems (A/S), ETH Zürich, Zürich, Switzerland.

Keywords: Urban Solar Potential, Data-Driven Model, BIPV, GAN, VAE

Building Integrated Photovoltaics (BIPV) is a promising technology to decarbonize urban energy systems via harnessing solar energy available on building envelopes. Nevertheless, handling the trade-of between efort, speed and spatial-temporal resolution for 3D BIPV solar potential evaluation in a complex urban context has always been a challenging task. Existing physics-based solar simulation engines require signifcant manual modeling efort and computing time to obtain high-resolution deterministic results. Yet, solar irradiation is highly intermittent and representing its inherent uncertainty may be required for designing robust energy systems. Targeting these drawbacks, this paper proposes a data-driven model based on Deep Generative Networks (DGN) to efciently generate high-fdelity stochastic ensembles of annual hourly urban solar irradiance time-series data with uncompromised spatial-temporal resolution at the urban scale. It requires only easily accessible data inputs, i.e., simple fsheye images as categorical masks, such as captured from Level of Details (LOD) 1 urban geometry models. Our validations exemplify the high fdelity of the generated solar time series when compared to the physics-based simulator. To demonstrate the model's relevance for urban energy design, we apply it to the resilient design of a district multi-energy system (MES) with several hundreds of BIPV surfaces. Furthermore, we showcase the models' potential for generative design by parametrically altering the urban environment and producing corresponding irradiation time-series in real-time.

## L Bragança s.8.41 1,2

and Innovation in Structural Engineering (ISISE). Automatic Verif cation of Urban Index Compliance: A Case Study for Brazilian Buildings

F Schmitd Villaschi1 , J P Carvalho1,2,

1 University of Minho, Brazil. 2 Institute for Sustainability

Keywords: BIM, Automatic Code Compliance, Computer Design, Urban Index

Urban planning has become an essential tool for regulating the cities' growth, maintaining the local urban identity and providing a good quality of life for its inhabitants. In Brazil, the master plan is the primary policy instrument for urban development and expansion. It defnes the common requirements that designers must follow when preparing building projects. Up to date, such projects are verifed in a project's latter stages and eventually approved by the city halls, with a manual calculation and assessment process. This procedure creates both the need to assess project compliance earlier to avoid rework and changes, as well as to automate project verifcation compliance, to reduce human errors. The emergence of new technologies and computational systems, such as Building Information Modeling, creates the opportunity for process automation by providing the required data to support decision-making. It also creates the opportunity to automate the calculation process for both designers and municipalities. Thus, this research aims to develop an assessment procedure which automates the compliance assessment of a

set of urban requirements from Vila Velha, Brazil. A BIM model was developed in Autodesk Revit to prove the procedure functionality and Dynamo was used to automate data collection and the calculation of three diferent indexes from Vila Velha's building code. By providing a fast and reliable analysis, the research framework provides designers with a realtime decision support tool, which indicates building compliance in the project's early stages. It also provides municipalities with a calculation tool, which can be used to assess the compliance of submitted BIM models, sparing time and avoiding assessment errors. Overall, the procedure has the potential to support building project design, increase process efciency and accelerate the verifcation of mandatory requirements. It also ofers the possibility for replication by adapting the routine to the mandatory requirements of each location.

#### s.9 Optimization

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Optimizing the Balance Between Flexibility and Structural Mass for Lower Short- and Long-Term Embodied Carbon Emissions in Mass Housing

S Gosling 1 , D Densley Tingley 1

1 Department of Civil and Structural Engineering, The University of Shef eld, Shef eld, UK.

Keywords: Embodied Carbon, Structural Mass, Flexibility

The building construction industry is one of the largest contributors to global greenhouse gas emissions. One solution to reduce the industry's carbon footprint is to design structures efciently, thus using less structural mass. However, over-designing is a fundamental aspect of fexibility; a building's capacity to make physical changes in the future – which is key for domestic buildings in particular. It is therefore important to strike a balance between structural efciency and high fexibility, to limit both short- and long-term embodied carbon emissions.

This balance was investigated using a mass housing case study, creating a series of design iterations to explore the trade-of between fexibility and structural mass. An optimum solution illustrated that this case study can be redesigned to have double the fexibility, lower structural mass, and less

carbon-intensive materials. Therefore, this research concluded that it is possible to signifcantly reduce the short-term embodied carbon emissions of this housing design, whilst simultaneously reducing long-term emissions too. Although these fndings might be specifc to this case study, the duplicate nature of mass housing means that the carbon savings of this one housing design can be multiplied many times across a whole development. Applying this research to other mass housing designs could signifcantly reduce the embodied carbon of future developments and improve the carbon footprint of the building construction industry.

An Integrated Form-Finding and Automated Fabrication Approach for Exploring Sustainable Shell Structures

S Baghdhadie 1 , O Kontovourkis 1 , M C Phocas 1

1 Department of Architecture, Faculty of Engineering, University of Cyprus, Nicosia, Cyprus.

Keywords: Shell Structures, Thrust Network Analysis, Computational Design, Flexible Formwork, Wasted Materials, Sustainable Construction

Latest advances in computational design and automated fabrication provide opportunities for form-fnding and precise development of shell structures in an integrated design to fabrication context. Implementation of these techniques cannot be completed without considering the negative efect of construction in the environment and the urgent need for environmental impact reduction through reusability and recyclability. This paper deepens into this direction by presenting a form-fnding/ automated fabrication approach of shell forms in combination with a recycle material implementation. The process starts by examining form-fnding possibilities of funicular forms by producing a series of case studies based on a number of controlled parameters, physical attributes and static performance criteria. Then, an alternative

use of construction materials is presented, in order to achieve sustainable properties, and adequate static performance of both, the overall structure and the individual structural components. In order to achieve this, cylindrical samples of diferent recycle material combinations are produced, tested under compression and their implementation is discussed. The suggested integrated form-fnding to automated fabrication approach ofers the opportunity for a holistic sustainable approach towards shell structures development, aiming at shape and performance viability through the selection of recycle materials.

The Cost-Optimal Optimization of Public Buildings in Cold and Warm Climates: Two Case-Studies in Germany and Italy

#### A Surname 5 , F Ascione 1 , N Bianco 1 , O Boettcher 2 , T Iovane 1 , M Mastellone 3 , G M Mauro 4, J Muehle 2

1 Department of Industrial Engineering - DII, Università degli Studi di Napoli Federico II, Naples, Italy. 2 BBSR - Federal Institute for Research on Building, Urban Afairs, and Spatial Development, Division WB 7, Energy-Optimized Building, Berlin, Germany. 3 Department of Architecture – DIARC, Università degli Studi di Napoli Federico II, Naples, Italy. 4 Department of Engineering - DING, Università degli Studi del Sannio, Benevento, Italy.

Keywords: Cost-Optimal Analysis, Building Simulation, Energy Refurbishment, Ofce Buildings, Multi-Objective Optimizations

Directive EU 844/2018, in the matter of energy performance of buildings and future goals of energy efciency for the EU Member Countries, extends the standard of nearly zero-energy building goals to the existing building stock, with the mandatory aim of almost complete decarbonization of the whole sector within 2050, and thus a strong reduction of greenhouse gas pollution of about 80-95 % compared to the levels of '90s. In this frame, the present study purposes the multi-objective optimizations of two ofce buildings, located in Berlin (Germany, European backcountry, »Cf« climate in the classifcation of Köppen and Geiger) and Naples (Italy, Mediterranean coast, »Csa« climate classifcation), with the aim of fnding the best trade-of between two couples of contrasting targets, representative of private and public interests, respectively: minimization of indoor thermal discomfort and operational costs,