Les règles de construction autrichiennes sont en retard par rapport à la nouvelle réalité thermique

Lead: Austria’s building regulations lag behind the new heat reality Austrian building codes have failed to keep pace with the growing threat of extreme heat, according to experts who warn that outdated temperature standards are leaving homes vulnerable during record-breaking summer temperatures. The issue has sparked calls for urgent revisions to current norms, which were last updated in 2023 but still rely on climate data from the period 1981–2000, data that does not reflect today’s increasingly frequent and intense heatwaves. The problem became apparent after recent measurements showed outdoor temperatures exceeding 40 degrees Celsius in cities such as Vienna, far beyond the limits used in current calculations. These outdated figures, embedded in the OIB guideline 6 (“Energy saving and thermal protection”), set maximum indoor temperatures for residential buildings at 29 to 30 degrees Celsius. However, experts argue these thresholds are no longer adequate. According to Alexander Sieh, a specialist in climate-adapted construction at the University of Applied Sciences Campus Wien, the threshold at which 90 percent of people feel comfortable has dropped to 26 degrees. Beyond this point, each additional degree becomes a burden. Living in a home with temperatures around 30 degrees for weeks is described as “unacceptable.” Current building codes allow developers to justify the lack of external shading systems in new constructions by proving that even without them, indoor temperatures would not exceed legal limits. This loophole means that passive cooling measures, such as external sunscreens, are often omitted from designs, despite their proven effectiveness compared to active cooling methods like air conditioning. Sieh argues that while air conditioners can provide immediate relief, they come with drawbacks: increased urban heat island effects, noise pollution, and a tendency among users to neglect essential passive strategies once they are available. He notes that many homeowners with air conditioning fail to maintain necessary shading, even when external protections are installed. To address this, Sieh suggests that legal frameworks should make shading systems easier to implement, particularly in existing buildings. While the government has announced plans to simplify the installation of split air conditioning units for tenants and property owners, he emphasizes that shading should remain the priority. For major renovation projects, active cooling techniques such as building component activation could be introduced. Additionally, he advocates for the wider use of window shutters in cities like Vienna, noting that they are standard in southern regions and contribute significantly to thermal comfort. Experts stress that every building must be evaluated individually using current climate data, especially existing structures. Sieh recalls that just two decades ago, summer heat was rarely considered in design. Now, with weather extremes accelerating and heat periods starting earlier and lasting longer, the delay in adapting building practices is being viewed as reckless. As temperatures continue to rise, the need for comprehensive updates to Austria’s building codes, and the implementation of both passive and active cooling solutions, is becoming more urgent than ever. The debate over how to balance comfort, sustainability, and regulatory compliance is likely to intensify in the coming months.