Conversion of Existing Buildings
Transformation Begins with Appreciation
When does it make sense to reuse an existing building – and when does it not? Rushing into planning can lead to overlooked opportunities or underestimated risks. Before deciding whether to preserve, transform, or replace a building with new construction, the first question should always be: What is the true value of the property?
Working with existing buildings is no longer the exception – it has become the norm. Yet this does not mean preserving every building at any cost. Rather, the challenge is to determine how existing buildings can be developed in a meaningful and future–proof way.
Successful transformation projects begin with a careful assessment of the existing building. But what defines the value of a property? And how can the opportunities and risks of transforming an existing building be assessed realistically?
Recognizing the Value Before Planning
Every project involving an existing building undergoes its own unique value transformation. The key to project success lies in identifying this value, translating it into every aspect of the project, and ensuring that it consistently guides decision–making throughout the entire project lifecycle. There is no universal benchmark for this. Every project has its own intrinsic value – and recognizing that value is the essential first step.
For me, every transformation project begins with appreciation. Not in a sentimental sense, but as a planning mindset: Only those who truly understand the value of a building can make informed decisions about its future.
Viktor Lorentz
Architect, Managing Director in Aachen
What Determines the Value of a Property?
The criteria that determine whether a property should be acquired, developed, or transformed vary from project to project. Factors may include location, site size, accessibility, structural integrity, energy performance, and the presence of hazardous materials. Less tangible qualities also play an important role, such as a building’s character, uniqueness, development potential, flexibility of use, and eligibility for funding.
Assessing a project's feasibility and economic viability also requires a detailed evaluation of the loadbearing structure, Building Services, building access, and floor load capacities, as well as regulatory conditions such as planning law and historic preservation requirements.
A former industrial building, for example, may offer exceptional development potential thanks to its generous spatial layout. An urban department store derives much of its value from its location and accessibility. A historic building can create added value through its distinctive character – a quality that new construction can rarely replicate.
There is no universal formula for transforming existing buildings. Every project must be assessed individually. Ultimately, the market also plays a decisive role. Whether a property can be developed successfully depends not least on demand – for student housing, office space, or retail, for example.
From Intuition to Reliable Value
The search for value often begins intuitively. We perceive a building as something special. We recognize its potential. We see qualities that cannot immediately be expressed in numbers. The challenge in project development is to translate this initial subjective impression into objective evaluation criteria. Only when these qualities can be described, substantiated, and formulated as concrete planning objectives do they become meaningful drivers of the project.
In my view, the greatest mistake in project development is skipping this step from intuition to reliable value. Critical issues must be identified as early as possible – before time, money, and planning effort are invested in concepts that ultimately prove unfeasible.
Appreciation does not mean preserving everything. Rather, it means weighing opportunities against risks and assessing a property's development potential realistically.
A Question of Compatibility
Not every building is suitable for every new use. As part of the valuation process, the existing building's structural, spatial, and technical characteristics must therefore be assessed objectively.
Downward–compatible development makes use of existing qualities for less demanding uses. A former industrial building, for example, often provides excellent conditions for offices, restaurants, or other public functions. Its existing loadbearing structure, generous ceiling heights, and long spans are qualities that new buildings can rarely offer today.
Upward–compatible development seeks to accommodate more demanding uses within an existing building and often reaches technical or spatial limits. In such cases, an initially promising concept may have to be abandoned – for example, when the transformation of a 1970s multi–story building is constrained by its rigid spatial organization.
Lateral–compatible development builds on the building's existing system logic and develops it further. Existing planning grids, for example, are retained and adapted in a way that remains consistent with the original building concept.
Successful transformation is achieved where the building structure and its intended use are compatible.
Historic Preservation – A Constraint?
Historic preservation requirements are often perceived as a limitation. In reality, however, they are always intended to protect specific qualities of a building. The key question, therefore, is whether these preservation objectives align with the goals of the transformation. When they do, they can create significant added value. The historic character of a building strengthens its identity, enhances its appeal, and can also provide economic benefits, for example through public funding. Where conflicts arise, it is essential to assess whether the advantages of the existing building outweigh the constraints or whether they stand in the way of meaningful development.
For this reason, I regard historic preservation neither with enthusiasm nor with concern, but as one component of an overall economic and planning assessment. Ultimately, the objective is always to recognize the true value of a building and use this understanding to make the right decisions about its transformation.
Replacing Uncertainty with Risk Assessment
Why do so many clients still hesitate to pursue transformation projects? In many cases, the answer lies in the fear of the unknown. Hazardous materials, incomplete documentation of the existing building, unforeseen structural issues, or unpredictable costs are still widely regarded as the typical risks associated with working with existing buildings.
These risks are real. However, they are far more manageable today than they were only a few years ago. Existing buildings can now be surveyed quickly and accurately using laser scanning. Hazardous materials can be identified at an early stage, loadbearing structures analyzed, and digital models of the existing building created from the collected data. The earlier these fundamentals are established, the more reliable subsequent project decisions become.
In my view, stripping the building back to its structural shell as early as possible is a sensible approach. Only once the structure and loadbearing system are fully exposed can many critical questions be answered with confidence. This significantly reduces the likelihood of unexpected issues arising during construction.
The same applies to existing documentation. Time and again, obtaining structural calculations and record drawings is postponed because they are initially considered unnecessary. My experience shows the opposite: they are always needed. If structural documentation or existing plans are missing, they must later be recreated at considerable additional cost and effort.
One of my fundamental principles for working with existing buildings is to replace uncertainty with risk assessment and risk management. This does not mean downplaying risks. It means identifying them at an early stage, assessing their potential impact, and using that knowledge as the basis for well–informed decisions.
Conclusion: Understanding Existing Buildings, Shaping the Future
Today, the majority of construction activity in Germany takes place within the existing building stock. In this context, transforming existing buildings is no longer a niche discipline – it has become the norm.
In my view, the foundation of every successful transformation project is recognizing the value of a property. Only then can informed decisions be made about its future. This value is not defined solely by the architectural significance of a building. It may lie in its structure, its location, its development potential, its identity, or its role within the surrounding urban context. Our task is to make this value visible and translate it consistently into structural, technical, economic, and functional planning criteria.
Transformation therefore does not begin with the design. It begins with understanding. Those who recognize the true value of a building can objectively weigh opportunities against risks, identify potential conflicts at an early stage, and establish a sound basis for decision–making. Sometimes this assessment leads to transformation; sometimes it points to new construction. Both can be the right solution.
What matters is that every project has its own unique value that must be identified on its own merits – creating the foundation for giving a building a second life that truly suits its character.
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