BAU 2027: Climate protection and climate adaptation in existing buildings
13.10.2026
Figure: Messe München
In the future, buildings will need to meet two requirements: significantly reduce greenhouse gas emissions while also functioning under different climate conditions. Hot spells and heavy rainfall place new demands on buildings and urban districts. One of the key themes at BAU 2027, which will take place in Munich from January 11 to 15, 2027, is how climate protection and climate adaptation can be combined in refurbishing existing buildings and planning new ones.
According to the Prognos study “Climate-adapted construction,” the necessary investments in the German building sector will total EUR 137 billion by 2035 in the event of mild climate change, and EUR 237 billion in the event of severe climate change. In the mild climate change scenario, 86 % of this will be for existing buildings, turning climate adaptation into primarily a matter of renovating and refurbishing.
Existing buildings are also a key lever when it comes to climate protection: Germany has almost 20 million residential buildings, many of which are several decades old. Only 7.7 % of today's existing buildings were constructed between 2010 and 2022. At the same time, more than three-quarters of residential buildings and apartments are heated with oil or gas. Energy-efficient refurbishment and switching to renewable heat must therefore be combined with adaptation to different climate conditions.
Heat becomes a design parameter
During planning, air temperature is only one factor to consider. Urban geometry, solar radiation, shading, wind, and surfaces shape the microclimate. As a result, very different stress conditions can arise even over short distances. Heavily sealed traffic areas and locations that lack shade are particularly affected.
“First of all, what the weather forecast says has nothing to do with development. What actually happens in the street depends very much on the city’s geometry, shading, wind, and materials,” explains Prof. Daniele Santucci, Professor for Building Systems at RWTH Aachen University.
As a result, summer heat protection for buildings is becoming increasingly important. Shading, storage mass, natural ventilation, and night cooling influence how much indoor spaces heat up and the resulting technical cooling requirements. In new buildings, these requirements can be taken into account from the outset in the orientation, cubature, and construction. In existing buildings, they need to be reconciled with the existing structures.
At the urban district level, trees, unsealing, and cold air corridors also play an important role. In densely built-up areas in particular, these measures compete with other uses of space. Streets, parking spaces, roofs, and facades can therefore also be used for shade, vegetation, or water retention.
Rainwater management and multifunctional spaces
Unlike river flooding, heavy rainfall can occur almost anywhere. Topography, soil sealing, development, and drainage influence where water flows and where it accumulates. Basements, underground car parks, lower-level entrances, and, increasingly, ground floors are particularly vulnerable. Flow paths and retention areas must therefore be considered beyond the scope of the individual building.
Copenhagen demonstrates how spaces can be used in multiple ways. As part of its “Skybrudsplan,” parks and public spaces can retain rainwater, while streets are used to direct water in a controlled manner. Outside of heavy rainfall events, these areas serve as green spaces, sports facilities, and recreational areas.
Roofs are also increasingly taking on multiple functions. Photovoltaics, building technology, greening, and rainwater retention all converge in a limited space. If the supporting structure, roof construction, sealing, and drainage are coordinated early on, these functions can complement each other. Retention roofs retain precipitation, while vegetation can use some of the water and evaporation influences the microclimate.
Climate adaptation begins in the early planning phase
The extent to which buildings and urban districts can adapt to heat and heavy rainfall is often already determined in the initial planning phases. Once buildings, access infrastructure, and space allocation have been largely defined, there is less scope for tree locations, retention areas, or safe drainage routes.
Urban climate analyses, heavy rainfall hazard maps, and digital models can help identify particularly vulnerable areas and plan suitable measures. It is crucial for these findings to be incorporated into the planning at an early stage.
This also increases the importance of collaboration between architecture, landscape architecture, urban planning, water management, and technical planning. Greening and retention must be coordinated with construction, sealing, building technology, and use.
Investment requirements for climate adaptation are increasing
Adapting existing buildings represents not only a planning and technical challenge, but also an economic factor. According to Prognos, the annual investment requirements through 2035 are around EUR 12.5 to 21.5 billion, depending on the climate scenario. Implementing the measures examined will require an additional 7,700 to 15,300 full-time employees, primarily to provide protection against heat and heavy rainfall.
At BAU 2027, manufacturers and planners will present constructive and technical solutions to these challenges. The range extends from building envelopes, sun protection, and building technology to roof and facade systems, rainwater management, and digital planning tools.
CONTACT
Messe München GmbH
Am Messesee 2
81829 Munich/Germany
