25.02.2026

Climate adaptation in construction contracts – How to legally secure sustainability

Building design

Architectural example that makes climate adaptation and legally secured sustainability visible in the building contract.

Climate adaptation is no longer a luxury, but a survival strategy – and its success is often decided where you least expect it: in the building contract. After all, those who fail to legally safeguard sustainable standards and climate protection ambitions remain dependent on capricious weather extremes and political arbitrariness. How can sustainability and climate adaptation be incorporated into the hard and fast rules of building practice? And how can legal instruments be used in such a way that they don’t just exist on paper?

Introduction: Why climate adaptation is indispensable in construction contracts today
The legal basis: From EU taxonomy to German building contract law
Practice: How sustainability and climate adaptation are specifically anchored in construction contracts
Instruments and methods: performance specifications, certifications, obligations to provide evidence
Risks, pitfalls and solutions when drafting contracts
Relevance for planners, local authorities, investors and construction companies
Examples from Germany, Austria and Switzerland
Outlook: Climate adaptation as a driver for innovation and quality assurance

Climate adaptation in construction contracts: from a political claim to an enforceable right

The images are omnipresent: flooded streets, cracked asphalt surfaces, dried-out parks, heat stress in densely built-up neighborhoods. Climate change has long since arrived on German, Austrian and Swiss construction sites. But while everyone is talking about heat-adapted street furniture, sponge city principles and green roof subsidies, one crucial question often remains unanswered: How do these measures become legally binding? After all, sustainable urban development is not a nice-to-have, but an obligation – and without clear legal safeguards, ambitious concepts are at risk of being shattered in construction practice.

The construction contract is the central control instrument in this context. This is where it is decided whether a building or open space is only climate-adapted on paper or is actually resilient to extreme weather and sustainable in the long term. Legislation has followed suit in recent years: From the EU taxonomy to the Building Energy Act and municipal statutes, climate protection is increasingly becoming a legal obligation. But how does this obligation actually find its way into contracts? And how can clients ensure that climate adaptation is more than just a fine-sounding declaration of intent?

Planners, local authorities and investors are faced with the challenge of not only formulating sustainability goals, but also enforcing them. This is precisely where the integration of climate adaptation into construction contracts comes in. A clearly formulated contract not only regulates the construction process and costs, but also ecological targets, verification procedures, adaptation measures and sanctions in the event of non-compliance. Those who ignore these aspects risk legal uncertainty, liability traps and – in the worst case – ineffective climate adaptation.

Practice shows: The more precisely and bindingly sustainability goals are regulated in the contract, the higher the implementation fidelity. Non-binding formulations such as “climate-friendly construction methods will be pursued” are worthless when push comes to shove. Instead, measurable, verifiable and comprehensible requirements are needed that are clearly understandable and enforceable for all contracting parties. This applies to public clients as well as private builders and investors.

In order to anchor climate adaptation and sustainability in a legally secure manner, a rethink of the contractual culture is necessary. Traditionally, construction contracts focus on deadlines, costs and construction quality – ecological targets have long been regarded as an optional extra. However, the challenges posed by the climate crisis call for a new prioritization: ecology must become an equally important contractual objective alongside economic efficiency and functionality. Only in this way will climate adaptation become a self-evident prerequisite for every construction project and not a bargaining chip.

Legal basis and current developments: How climate adaptation becomes a contractual condition

The legal landscape surrounding climate adaptation and sustainability has become much denser in recent years. While the European Union is creating a binding framework for sustainable investments with the Taxonomy Regulation and the Green Deal, the thumbscrews are also being tightened at national level. In Germany, for example, the Building Energy Act (GEG) obliges building owners to meet high energy standards, while the amended state building regulations increasingly require greening and rainwater management measures.

A lot is also happening in public procurement law: the awarding of public construction contracts can be linked to sustainable criteria, provided these are factual and legally secure. Local authorities can, for example, stipulate the construction of green roofs, the use of climate-friendly building materials or the implementation of heat reduction measures as binding contract components. The trick is to translate the general objective of “climate adaptation” into concrete, verifiable and enforceable contractual clauses.

Another key instrument is environmental and sustainability certificates such as DGNB, LEED or BREEAM. They offer standardized criteria catalogs that can be included as a reference in construction contracts. This provides planners and building contractors with clear specifications that can be checked during the execution of the contract. However, caution is advised: Certificates are no substitute for individual contract drafting and, in the event of a dispute, can only have as much effect as they were actually contractually agreed.

Case law continues to develop dynamically. Disputes relating to sustainability targets are increasingly ending up in court – for example, if agreed greening measures are not implemented or energy efficiency values are not met. The trend is clear: courts expect clear, concrete and measurable contractual provisions to enable the implementation of climate adaptation measures. Vague formulations lead to uncertainties and can be a boomerang for both sides.

The trend is similar in Austria and Switzerland: sustainability and climate adaptation are increasingly being anchored in building legislation and funding programs. Here, too, the following applies: if you are serious about the claim, you have to write it into the contract – and in such a way that it will stand up in case of doubt before the courts. The path to a climate-proof city therefore leads through paragraphs, not just visions.

From theory to practice: how to integrate climate adaptation into building contracts with legal certainty

The legal integration of climate adaptation into construction contracts is not rocket science, but it does require care, specialist knowledge and a willingness to break new ground. The first step is a precise specification of services. Here, requirements for sustainable materials, building technology, greening, rainwater management or heat protection are formulated in such a way that they are technically clear, measurable and verifiable. Terms such as “environmentally friendly” or “climate-friendly” should be avoided if they are not clearly defined. It is better to refer to specific standards, norms or certificates – such as DIN 18599 for energy efficiency or the DGNB system for sustainable building.

Another important element is the definition of verification obligations. The contractor should be obliged to prove compliance with the agreed climate adaptation measures by means of suitable documentation, test reports or certificates. Regular monitoring during construction – for example by independent auditors – can also be contractually stipulated. This ensures that sustainability is not just an aspiration, but actually becomes a reality.

Risks and uncertainties should not be underestimated. Climate adaptation measures are often technically complex, require interdisciplinary expertise and may require adjustments during implementation. Contracts must therefore be flexible enough to be able to react to new findings or changed framework conditions – for example through adaptation clauses or supplementary regulations. At the same time, it is crucial to clearly regulate responsibilities and liability issues in order to avoid disputes later on.

The integration of sustainability goals into the contract structure affects all project phases – from planning to execution and operation. Clients who demand that a building or open space must comply with certain climate adaptation measures should also keep an eye on subsequent use and maintenance. Here, so-called operating obligations or monitoring requirements can help to ensure long-term compliance with the targets.

Experience shows that contracts that clearly regulate climate adaptation and sustainability are a win-win situation for all parties involved. Clients receive legally compliant implementation, planners and construction companies benefit from clear specifications and minimized liability risks, while the environment benefits from real improvements. However, this presupposes that everyone involved – from the local authority to the investor to the construction manager – pulls together and sees sustainability not as a stumbling block, but as a quality feature.

Pitfalls, stumbling blocks and solutions: How to really implement climate adaptation

Integrating climate adaptation into construction contracts is not a sure-fire success. Typical pitfalls lurk in several places. Sustainability goals are often taken into account in the planning stage, but are not included in the contract documents – for example, because they are formulated as a non-binding declaration of intent or because there is a lack of detail. During implementation, discussions then arise as to whether certain measures were actually owed. Only one thing can help here: precision and clarity in the drafting of the contract.

A further risk is that climate adaptation measures are watered down in the course of the contract – for example due to subsequent changes, cost pressure or misunderstandings between the parties involved. To prevent this, a common understanding of the objectives and requirements should be established as early as the contract negotiation stage. Workshops, guidelines and checklists can help with this, as can the early involvement of all relevant stakeholders.

The provision of evidence is also a critical point. Without clear guidelines on how and when sustainability measures are to be documented, there is a risk of negligence and disputes. Binding inspection and acceptance processes that are explicitly regulated in the contract are recommended. This includes, for example, the submission of certificates, protocols or measurement data as well as the possibility of imposing sanctions in the event of non-compliance – up to and including rectification or contractual penalties.

An often underestimated problem is the interface between construction and public procurement law. Public clients must ensure that sustainability criteria are both compliant with procurement law and effective under construction contract law. There are numerous examples of cases in which well-intentioned climate targets have failed due to hurdles in public procurement law. The solution lies in the close integration of planning, tendering and contract design – as well as in the ongoing training of those responsible.

Last but not least: climate adaptation must not become a cost trap. Clients should realistically calculate sustainability targets and develop innovative, economical solutions together with the planners. Funding programs and tax incentives can help to cushion the additional costs and increase the attractiveness of sustainable construction projects. In the end, it’s not just the contract clause that counts, but also the joint commitment to a climate-proof future.

Examples, innovations and outlook: Climate adaptation as the quality standard of tomorrow

Successful practical examples show how climate adaptation and sustainability are becoming the new normal in construction contracts. In Hamburg, for example, green roofs, rainwater retention and heat-adapted open spaces are stipulated as binding contractual objectives in major neighborhood developments. The city of Vienna relies on comprehensive monitoring of sustainable construction work, which is already anchored in the tender and in the contract. In Zurich, investors must provide evidence of the effectiveness of climate adaptation measures during operation – otherwise they face contractual penalties.

These approaches show that Climate adaptation is not an add-on, but an integral part of modern construction contracts. It promotes innovation, quality assurance and cooperation between all parties involved. Digital tools such as Building Information Modeling (BIM) or GIS-supported monitoring open up new possibilities for precisely defining, checking and tracking sustainability goals – long after the building has been accepted.

New assessment methods, life cycle analyses and participatory planning processes are helping to ensure that climate adaptation is not seen as a bureaucratic obligation, but as a creative driver for better cities. The challenge is to translate these findings into the language of contracts and make them understandable and manageable for all those involved.

For planners, local authorities and investors, this means that climate adaptation is not a fashionable topic, but a key competitive and quality factor. Those who plan and build with legal certainty protect themselves against liability risks, increase the value stability of their projects and make a real contribution to the future viability of cities. Legal protection is not a form of coercion, but an instrument of self-assurance and the joint achievement of objectives.

Looking ahead, it is clear that climate adaptation will become an even stronger contractual basis in the coming years – driven by regulatory requirements, social pressure and the tangible consequences of climate change. Those who set the right course now will gain a decisive head start – and show that sustainable urban development is not just lip service, but a living reality.

Conclusion: Climate adaptation in building contracts is not a marginal issue, but perhaps the most important lever for sustainable urban development in German-speaking countries. The legally compliant integration of sustainability goals requires expertise, diligence and a clear will to change. Precise service descriptions, clear obligations to provide evidence and innovative monitoring methods create the basis for real resilience and quality. Those who make climate adaptation a contractual standard are setting benchmarks – and ensuring not only the success of their own projects, but also the future viability of our cities. The time for declarations of intent is over: sustainability is now contractually secured – and that’s a good thing.

06.09.2025

Industry news

De Wit: Vapors that defy time

Building design

The De Wit tapestry manufactory in Mechelen, Belgium, is world-famous. Here, antique tapestries from all over the world are cleaned and restored with the utmost care. © De Wit

Light, dust and insects are their enemies: antique tapestries are restored at the Royal Tapestry Manufactory De Wit in Mechelen thanks to a self-developed and patented cleaning system. […]

Light, dust and insects are their enemies: antique tapestries are restored at the Royal Tapestry Manufactory De Wit in Mechelen thanks to a self-developed and patented cleaning system.

Even in the early Middle Ages, they were mostly used to decorate ecclesiastical buildings. The motifs of the tapestries made in monasteries were religious, but changed in a courtly context when the tapestries were also made for the aristocratic class. During state visits and ceremonial celebrations, the ornate tapestries were hung in interior rooms and on exterior façades. They were also used as room dividers to improve acoustics and insulate castle walls from the cold and draughts. As commissioned works, they were based on the dimensions of the respective rooms; large-format tapestries could even decorate entire sequences of rooms. For a long time, they were reserved for the rich and powerful, as they could take several years to produce. After all, tapestries were easy to transport when rolled up and could be hung anywhere for display purposes.

A contract between the client and the tapestry dealer, which set out the conditions for the workshop, contained information about the function, material and size of the tapestry. The client chose the painter and determined the motifs with him. If silk, gold or silver threads were to be used, this increased the price. First, a small sketch was made on paper. This was then enlarged into a drawing. The workshops then translated the design into a textile image. In the late Middle Ages, the cities of Constance, Basel and Strasbourg were among the most important centers of warp knitting. From Brussels to Tournai, the southern Netherlands, which controlled the wool trade due to its proximity to England, then became the main production area. Incidentally, only tapestries from the Manufacture des Gobelins in Paris are considered “tapestries”.

Today, Mechelen to the north of Brussels preserves the tradition of Flemish tapestry art. The Royal Tapestry Manufactory De Wit is located in the brick building of Tongerlo Abbey dating from 1484. It has been run by the fifth generation of the De Wit family since 1889. The founder, Theophiel De Wit, learned the tricks of the trade as an apprentice at the French company Braquenié in Mechelen. He achieved his first successes by adapting to local taste, which demanded only reproductions or variations of the most famous tapestries of the past. Within a few years of handing over responsibility to his son Gaspard, the number of looms and employees had tripled. Contemporary artists were commissioned with the motifs and, with state support, the company survived the economic crisis of 1929. In the early 1980s, the concept was finally changed due to a lack of demand and the focus shifted to trading, collecting and, above all, the techniques of conserving and restoring historical pieces. At this time, the company also acquired the Tongerlo Abbey in the old town to set up the workshops there.

Thanks to its unique infrastructure, which concentrates all aspects of the treatment of antique tapestries within the same laboratory, the manufactory is now a world leader in the preservation of ageing wool and silk tapestries. It also plays a pioneering role in the development of new techniques. Damage is usually caused by the effects of insects, dust, water and light. Nails and screws also leave their mark. Added to this are improper previous repairs and incorrect storage, for example when the fabrics have been folded instead of rolled.

In the past, it was common practice to wash tapestries in temporary baths made of polyethylene and plastic pipes. Cleaning required large quantities of softened and deionized water as well as sufficient drainage. The tapestry was completely immersed in the bath. Mechanical action in the form of a sponge was also essential. To ensure that the entire surface of the tapestry received the same treatment, it was rolled on a roller in the bath. The repeated rolling and unrolling exposed the fabric to considerable stress. The mechanical action could damage delicate threads. The process was lengthy and drying could take between 12 and 24 hours, allowing potentially volatile dyes to spread.

Pierre Maes, the son of Yvan Maes De Wit, leads a team of 15 restorers and art historians as they move through rooms full of colorful balls of wool. Women in white coats bend over long restoration chairs on which centuries-old tapestries are stretched. They have a handful of spools of fine wool and silk in countless shades: ochre, bronze green, blue and crimson. They were selected to match the colors of the damaged weaving. “Our work consists of stabilizing the fabric with a linen cloth placed on the back, which is sewn with these silk threads. In the case of larger gaps, we try not to rework the tapestry identically, but to integrate these gaps into the composition through minimalist interventions,” says Pierre Maes. “When we restore tapestries, we don’t simply weave gold or silver underneath just to make it look better or appear more valuable. Each piece gives us the broad outline of its composition – and we follow it.”

The manufactory sometimes dyes the silk and cotton threads used itself in its laboratory with hundreds of synthetic pigments in order to preserve the colors of the tapestries and guarantee their quality. Before they can take these steps, however, the pieces must first be cleaned. The aerosol suction cleaning method used here was patented over 30 years ago. The suction method has since established itself throughout the museum world as the benchmark method for cleaning antique fabrics. Washing is a risky step: over the years, the cotton has often frayed and the silk has often been pulverized by the effects of time and light. The scientific approach, in which every step is carefully recorded and documented, has set standards.

The system uses a combination of aerosol spray and vacuum suction. It is equipped with integrated sensors to control the pH value, temperature, water flow and pressure. The system consists of a closed chamber with glass panels. The base is a large 5 x 9 meter suction table. There are 45 aerosol sprays attached to the ceiling, approximately 1.75 meters above the platform. During the cleaning process, the tapestry is held in place by continuous suction. When the aerosol is switched on, the chamber fills with water vapor, which is drawn evenly through the entire tapestry. A low concentration of a non-ionic detergent is introduced into the aerosol system for as long as it is deemed necessary for soil removal. This is replaced by softened and then deionized water during the rinsing process.

The subsequent drying process takes place at 30 degrees. Unstable colors flow into the collecting basin. This procedure, including drying, takes around eight hours and is controlled by a series of computers and chemical tests. Famous pieces such as the “Lady with the Unicorn” from the Musée de Cluny in Paris, “Los Honores and Los Paños de Oro” from the Patrimonio Nacional in Spain or the “Le Dais” tapestry by Charles VII from the Louvre have already undergone the process. Regular customers also include private collectors and important collections, such as Spain’s Patrimonio Nacional, the Kunsthistorisches Museum in Vienna, France’s Mobilier national and the Louvre, the Bavarian National Museum in Munich and the UK’s National Trust. “We are in the fortunate position of being able to carry out the most important and most beautiful restoration commissions that are awarded internationally,” says Pierre Maes. And in his hands and those of his highly focused team, they receive the care that these treasures, which are highly prized at art fairs such as TEFAF in Maastricht or BRAFA in Brussels, deserve.

19.12.2024

Artful interlocking

Building design

Living

“Building on” was the motto for the extension of a semi-detached house in Aachen. With a keen sense for the existing, the Amunt architectural office has created an extension that artfully combines the old with the new.

The small house, which is located in a workers’ housing estate on the northern outskirts of Aachen, was purchased by a family of three in 2010. As the floor space of 70 square meters proved to be too small, it was clear from the outset that an extension was needed. The solution was a two-storey extension that cleverly picks up on the cubature of the existing building and at the same time generates an open, independent structure.

The architectural theme of interlocking is a common thread running through the building. Both the shaping of the volume and the spatial organization follow this principle. While the extension on the first floor is clearly recognizable as a new part of the building thanks to the exposed concrete skeleton, on the upper floor it takes up the roof shape of the existing building and creates a polygonal roof sculpture that links old and new.

The floor plan works in the same way. The additional living and dining room is designed as an open “garden room”. The extensive glazing provides a view of the garden, while the brick façade of the existing building becomes an interior wall. The floor above accommodates four bedrooms, two of which are in the extension. Due to the spatial overlap at the intersection of the roof surfaces, the interior bathroom can be naturally lit via a light well. At the same time, its ceiling serves as a sleeping gallery for the adjoining children’s room. The staircase, which forms a transition zone, is of particular importance. An air space has been added to it, making the wooden beam ceiling of the extension visible on the upper floor, as well as the brick wall of the existing building.

The theme of interlocking is most evident in the façade. The unrendered pumice lightweight concrete brick of the extension merges with the clinker brick of the existing building at the verge. Both parts of the building merge into a single unit, but at the same time can be distinguished from each other by the resulting “seam”.

The architects wanted to take away the “hard newness” of the building and incorporate the character of the estate into their design. Thanks to precise interventions, they succeeded. They have created a homogeneous structure whose history remains legible.

Photos: Filip Dujardin