5th construction industry 'Baustammtisch' meeting

The earth is getting warmer and warmer, which is resulting in worse and more frequent extreme weather events. For buildings to continue to offer protection and safety, their shells must become more resilient. But how can we improve the resilience of construction materials for façades, roofs and cellars? The experts invited to the round table at the 5th construction industry 'Baustammtisch' meeting on 11 May 2023 discussed this and other questions.

Thomas Pöll, Editor-in-Chief of SOLID magazine, moderated the fascinating discussion entitled "How can building shells withstand climate change?".

The podium comprised: Markus Atzwanger, Team Leader System Development, Swisspearl Österreich GmbH, Marc Höhne, Managing Director, Delta Projektconsult GmbH, Werner Linhart, Court-Certified Expert, Doris Österreicher, University Lecturer, Institute of Spatial Planning, Environmental Planning and Land Rearrangement, University of Natural Resources and Life Sciences, Vienna and Partner at Treberspurg & Partner Architects, Sandro Oswald, Urban Climatologist, GeoSphere Austria (previously ZAMG), and Engelbert Schrempf, Managing Director, Holzbau Austria and Vice Chairman for Timber Construction in Styria.

Are building shells at their load limits?

Urban climatologist Sandro Oswald provided a very detailed description of current climatic trends and forecasts: "Extreme events that used to happen once a year are now occurring three times a year. By 2050 we anticipate this increasing to five events during the same period. Drought, heavy rain and hail are becoming more extreme because more and more energy is being discharged in one place."

Markus Atzwanger was able to confirm this from personal experience: "It is clear to see that damage from hail in Upper Austria has increased significantly." He believes that standards for construction are an important requirement for being able to quantify this trend and countering it with new load standards. But: "When it comes to hail, construction products are already at their load limits. There is no longer any buffer for higher safety limits."

Hailstones seven centimetres in diameter, dropping at a speed of 130 km/h, are now totally realistic – and no roof tile will come through that unscathed. The experts agreed that to date green roofs and pebble roofs have demonstrated the best values when faced with severe hail.

Engelbert Schrempf added: "Since 2022, there has been a new standard for snow loads for calculating supporting structures and the snow load map has been updated. Analysing data has found that the total volume of snow has decreased, but that snow now falls within a shorter period of time and puts roofs under concentrated strain."

Wind loads are also rising drastically. "Small-scale tornadoes, like the one recently in the Waldviertel region of Lower Austria, won't be uncommon," confirmed Sandro Oswald. The good news is that as far as protection from wind and flooding is concerned, everyone on the panel sees a lot of scope for improving the resilience of building shells both in terms of products and existing components as well as planning.

A new approach

Werner Linhart: "We need to think ahead in terms of planning and construction so that buildings can still be used in fifty years' time. Existing buildings are a complicated topic. But again here, we have scope for toughening up components and structures."

Doris Österreicher also believes that the construction industry needs to plan with sustainability and future-proofing in mind. "This also includes topics such as energy supplies for buildings and land use." In the future, building shells will contribute even more to energy supply needs. For heavy rain to be able to run off unhindered, it is essential that we reduce the amount of land covered in concrete.

Marc Höhne is seeing a trend amongst developers and owners where the focus is shifting back to considering real estate more as buildings and less as investments. However, the degree of suffering is currently "probably not yet great enough". When it comes to existing buildings in particular, a lot of owners and investors are still hesitant to invest in renovations fit for future climates.

What do building shells need to be able to do?

Everyone agreed that green roofs, as well as light-coloured roofs and façades, are effective when confronted with overheating. The irrigation and care of plants and flora in green structures must be taken into account right from the outset. "Just as several buildings can be connected to form small energy networks, the same can be done with water tanks. This requires an innovative and integrative development of districts," said Doris Österreicher.

Engelbert Schrempf: "In terms of the individual building, it would be a good idea to separate the shell from the supporting structure and fit a sub-roof. The various layers then need to be easily accessible for maintenance and upkeep." Schrempf also mentioned projecting roofs and a move away from flat roofs in response to increasing heavy-rain events and snow loads.

Werner Linhart was also convinced by a "wearing surface as a reserve level". In the event of severe damage, a second, redundant layer can protect the core until all repairs are complete. "The alternative would be concrete bunkers, if we don't want to risk total damage in the long term." The resilience of building shells should also be made dependent on usage. At the end of the day, there is a difference between whether vehicles are having to be protected in a hall or whether it's a matter of life and limb.

 

A whole host of building blocks for individual solutions

Overall, the panel agreed that we are going to need lots of ideas and individual solutions for building shells to withstand climate change. Glass surfaces which have an aesthetic appeal yet bring no added value and waste energy are definitely out, as are façades in dark anthracite that heat up a lot.

In contrast, hybrid construction methods, innovative construction materials and smart constructions as well as the clever development of districts and effective choices of location are important building blocks for buildings to be able to protect us from the wind and weather in the future.

More on the topic

• Press release: How climate change is affecting building shells: the construction sector is readying itself
• Read all about the 4th virtual construction industry 'Baustammtisch' meeting: Accessible planning and construction means greater convenience for everyone
• Read all about the 3rd virtual construction industry 'Baustammtisch' meeting: "Green" renovations: No "black and white" answers and demolition only as a last resort
• Read all about the 2nd virtual construction industry 'Baustammtisch' meeting: Sustainable construction requires know-how and true-cost pricing
• Read all about the 1st virtual construction industry 'Baustammtisch' meeting: En route to the BIM library: ensuring that "BIM" doesn't become a Tower of Babel

More information about the Austrian Construction Dialogue Board (Dialogforum Bau Österreich)

www.dialogforumbau.at