How buildings change and practices for adaptation without alteration in Danish construction.
Tobias Hentzer Dausgaard’s doctoral thesis explores how buildings can be designed or adapted to sustain use-value over time with less material demand. Analysing nearly 300 years of alterations to nine buildings in central Copenhagen, it documents the substantial material consumption and embodied carbon associated with refurbishment and transformation. It also shows how architectural composition and practices of use shape both building change and material demand over time. These findings inform design principles and methods for designing and adapting buildings to accommodate changing needs with fewer or no physical alteration.
Overall, the thesis addresses a gap across building adaptability and sustainability research, architectural practice, and building legislation: the lack of a structured, comparative, and longitudinal account of how buildings change, of the material flows and alteration-related embodied carbon associated with those changes, and of the use-value the buildings sustain. Specifically, alterations from LCA module B5 Refurbishment and transformations of use are studied. While contemporary approaches to refurbishment and adaptation often emphasise technical building performance, the thesis combines quantitative assessment of material flows and climate impacts with qualitative interpretation of use-value, and examines how architectural composition and practices of use condition both alteration-related material demands and sustained use-value.
The study combines methods from environmental engineering with historical and architectural research, Research by Design, and action research methods. Its empirical basis is a longitudinal comparative study of nine multistorey buildings in central Copenhagen – originally schools, housing, and offices – spanning nearly 300 years and representing three stages of industrialisation in building practice: before 1850, 1850 to 1959, and since 1960. Construction archives were synthesised through drawn alteration-history mappings subsequently used for material flow analysis, life cycle assessment, a preliminary life cycle costing study, and qualitative architectural analysis. The thesis uses Research by Design as an overarching methodology for its three main parts: 1) developing an empirical baseline with research about design, 2) identifying design principles for practice with research for design, and 3) transfer into practice with research for, and partly through, design.
The first main contribution is an empirical baseline for building alterations and their material consequences. The quantitative analysis included documented alterations (LCA module B5 and transformations of use), but excluded maintenance, repair, and 1:1 component replacement within other B-modules. Across the nine case study buildings, the average alteration-related embodied carbon was over 1.5 kg CO₂-eq/m²/year. The three buildings constructed since 1960 recorded an average of nearly 5 times the average of the six earlier buildings.
The common-period sensitivity analysis for 1976-2025 reduced this factor to nearly 3 but retained a substantial difference. In the since-1960 case study buildings, alteration-related embodied carbon was concentrated in building envelopes and installations, whereas in the earlier buildings it was concentrated more in the interior fittings.
Together, the findings show that the environmental importance of retaining and adapting existing buildings does not remove the need to consider the environmental impacts from material flows produced by refurbishments and transformations of use throughout buildings’ lives. A preliminary LCC analysis of four cases found that the since-1960 case had present-day annualised acquisition costs over 2.5 times the average of the three earlier cases.
The Danish regulatory new-build LCA currently omits module B5 Refurbishment and other forms of alteration. The since-1960 average is equivalent to about 50 of the planned 2027 new-build limits. If buildings constructed today were to undergo comparable alteration patterns, their life-cycle impacts could thus be approximately 50% higher or more than their calculated impact for the modules covered by those regulatory limits. Therefore, the thesis proposes developing progressively tighter limits on cumulative B5-related embodied carbon alongside recording actual B4 replacement dates and comparing replacement intervals with the tabulated component lifespans assumed in the building’s original LCA calculation, while supporting continued building use and adaptation over demolition.
The second main contribution is a theoretical revision of dominant building-change models and the development of design principles, change dynamics, and the concept of stubborn architectures. The thesis challenges Frank Duffy and Stewart Brand’s functional layer models as sufficient explanations of actual alteration histories because their proposed hierarchies did not consistently recur in the corpus, either in terms of alteration frequency or extent. Instead, elements within the same category tended to change differently and elements across categories tended to change together.
To address the explanatory gap, the qualitative analysis identifies relationships both within architectural compositions and between compositions and use practices that condition adaptation outcomes in terms of sustained use-value and alteration-related embodied carbon. The thesis also supported a cultural critique of treating technical performance criteria as an adequate proxy for use-value because greater material flows and higher technical performance did not necessarily produce greater or more sustained forms of use-value.
Fifteen design principles were identified and their explanatory levels synthesised into five change dynamics – Alliances, Margins, Care, Situated Comfort, and Communication. These dynamics shifted the explanation of building change from functional or component properties towards a relational and temporal account of how architectural composition and use practices condition whether and how buildings are altered, while alterations modify conditions for later adaptation. Stubborn architectures provide a normative synthesis across the change dynamics, concerned with what alteration is sufficient for adaptation to be possible rather than taking alteration as a given.
By supporting architectural judgement in sustaining use-value and adaptation possibilities while reducing alteration-related material demand, stubborn architectures assert the value of qualitative, temporal, and contextually specific judgement to complement more widespread technical performance criteria and measurements. Both are necessary for reducing use-stage material demand.
The third contribution concerns how building-change knowledge can be transferred into and create value in architectural practice. Six pilot projects, mainly at RØNNOW LETH & GORI, examined preliminary design principles and alteration-history methods in early and pre-design stages across new-build, transformation, modernisation, and strategic projects. The pilot projects developed situated transfer methods and provided evidence of how principles and alteration histories could operate as prompts for architectural judgement, reflection, prioritisation, client communication, and brief development.
These methods may be of particular relevance to working with long-term building owners concerned with environmental impacts, long-term costs, and sustained value for users throughout a building’s life, across new construction and transformation projects.
Overall, the thesis argues for lasting architecture as a form of use-stage material sufficiency; a sufficiency that can neither be reduced to austerity nor technical efficiency. A building may require fewer materials over time not because it offers less to its users, but because the relations between architectural compositions and use practices can make some forms of alteration unnecessary while sustaining use-value over time.
Buildings of use-stage sufficiency could give users and owners the freedom to adapt and adjust their buildings to changing needs even if environmental, political, legislative, supply, and global and individual economic conditions change.
Stubborn architectures connect this explanatory and projective knowledge to architectural practice and, with this, the thesis proposes to seek abundance of use-value over time through reduced material use, using only what is sufficient for adaptation. What is sufficient, however, cannot be determined through material quantities alone but requires critical judgement of whose needs adaptation serves and for which publics use-value is ultimately sustained.
“We aim to create strong and close connections between research and practice in our projects. Through broad interdisciplinary collaborations, the goal is to develop new knowledge and design processes in (re)formulating lasting architecture in practice – from environmental and resource perspectives, to social and cultural as well as to live cycle costs perspectives,” Karsten Gori, RØNNOW LETH & GORI, says.
“It’s an important project where, through our role as a major and significant developer, we hopefully can help shape the industry. In other words, we need to get better at ‘doing a lot with a little’. The project should make us wiser about how we build new buildings, adaptive reuses and additions sustainably through the development of actionable and concrete solutions,” Lisa Jørgensen, project manager at Byggeri København, adds.
Supervisors
Aarhus School of Architecture | Professors Mogens A. Morgen, Marie F. Hvejsel, and Lotte B. Jensen.
ETH Zurich, gta | Professor Laurent Stalder
RØNNOW LETH & GORI | Partners, Karsten Gori and Inge-Lise Kragh
Third Parties
Byggeri København (Municipality of Copenhagen’s developer unit) | Senior project manager, Lisa Jørgensen
Eduard Troelsgård Consulting Engineers | Partner and director, Tom Hansen
Advisory Group
Freja Ejendomme (Danish State Property Development Corporation) | Head of sustainability, Ninette Mahler Alto
Værdibyg (The Danish Association of Construction Clients) | Vice program director, Nina Koch-Ørvad
Byggeskadefonden (The Danish Construction Defects Fund) | Head of Sustainability and technical expert, Charlotte Gudum
GI (The Landowners’ Investment Foundation Denmark) | Head of Innovation, Søren Meyer
Aaen Engineering | Owner and founder, Micki Aaen
The project is supported by the Innovation Fund Denmark with 1.1 million DKK.
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