Building regulations out of step with climate data

Forecasts from the German Weather Service predict that by 2045 the amount of summer days over 25 degrees Celsius is set to increase from 40 days to as many as 69 days per year   – with hot days above 30 degrees Celsius increasing from 5 days to up to 26. This is a fundamental shift in weather patterns, raising concerns about the overheating of buildings with potential impact on comfort, energy use and health for occupants.

However, the study reveals that outdated standards such as DIN 4108‑2 still rely on historical climate data from 1988 to 2007 – a period that no longer reflects current or future realities. As a result, buildings may technically meet today’s regulations while still overheating in real‑world use.  What makes this critical is that there are no binding requirements or building regulations for protection against extreme summer heat in existing buildings. The lack of regulation reform may well pose a significant risk when it comes to the futureproofing both existing and new build homes.

Cooling as the new energy burden

One of the study’s most striking findings is the dramatic imbalance between winter heating and summer cooling. Under expectable future climate conditions, cooling a room to 22°C in summer can require more than five times the energy needed to heat it in winter. This becomes especially problematic when buildings that lack structural heat protection turn to mechanical cooling to compensate. Poorly shaded, highly glazed rooms quickly accumulate solar gains. Occupants relying on mechanical cooling as an emergency response instead of investing in proper solar shading will very likely cause a major problem for the energy supply system. Based on the study, the RTG urges political decision makers to no longer regard this as a tomorrow’s problem.  

Described is an “energy policy time bomb” by the researchers, the problem with mechanical cooling is poised to become a serious energy burden.  The widespread adoption of active cooling will amplify electricity demand, precisely at a time when climate change is putting strain on the grid.

Whilst the energy burden of cooling is a significant finding, the analysis also highlights the enormous potential of structural measures to mitigate overheating. In many scenarios, well‑designed and automated shading systems can maintain comfortable indoor temperatures without relying on air conditioning at all.

Even simple comparisons in the simulations referenced in the study, show that effective external solar shading can more than halve cooling energy demand, sharply reducing indoor heat loads before they ever enter the building. In fact, the study’s modelling shows that in many scenarios – particularly, south‑facing, 70% glazed rooms common in modern architecture – well-designed, automated shading can maintain indoor temperatures around 26°C with almost no active cooling – even during future August heat peaks. This performance advantage becomes even more pronounced when shading is activated earlier in the day, preventing heat accumulation before it becomes unmanageable.

These findings underscore that intelligent building design – shading, glazing and automation – can work effectively together to counter the threat of overheating in buildings.

Why 26°C matters?

The modelling used for the study repeatedly references 26 °C as a pragmatic comfort threshold under heat stress. This temperature is not just a technical benchmark. Hitting and holding that threshold reduces heat‑related health risks, preserves cognitive performance, and stabilises productivity in offices, schools and clinical environments.

External shading lowers mean radiant temperature as well as air temperature, so occupants experience real comfort gains even when thermostats are set a degree or two higher – a vital margin during heatwaves. These effects are most reliable when automation coordinates shading with daylighting targets and natural ventilation.

Importantly, keeping indoor conditions near 26 °C without defaulting to air conditioning supports vulnerable groups (children, older adults, patients) and avoids saddling households with operating costs for cooling equipment that may be used only a few weeks each year – a classic efficiency trap the study warns against.

Solutions no longer a luxury

For a long time, solutions like automated solar shading, responsive façades and nighttime ventilation systems were considered desirable, rather than essential in building design. However, as Germany’s weather patterns are accelerating towards hotter summers, architects, engineers and policymakers are shifting in their views on solutions once considered exclusive. These solutions are increasingly considered as health interventions, productivity enablers, energy-saving technologies and cost-effective retrofit options.  The IBH study underlines that adaptation is needed in both new builds and the retrofit of existing buildings – given that these structures will still be in existence in 2045.

A practical roadmap for change

The study outlines three core actions to establish a path to heat-resilient buildings in the future. 

1.         Modernise building standards

Regulations must incorporate future climate scenarios, not past ones, and embed requirements for dynamic shading, natural ventilation, and smart controls.

2.         Retrofit at scale

Retrofitting existing buildings with shading solutions, updated façades, and ventilation strategies is essential, particularly given the age, diversity, and sheer volume of Germany’s building stock.

3.         Strengthen policy alignment

Both industry bodies and government agencies are calling for urgent action. Standards must evolve in tandem with these insights, creating a unified approach across design, regulation, and construction.

The conclusion is that Germany’s built environment stands at a critical juncture. The IBH study underscores a simple truth: dynamic solar shading and solutions like it, are no longer optional. It is one of the fastest, most efficient, and most scalable solutions for protecting buildings and the people occupying them from rising heat.

By updating standards, prioritising retrofit strategies, and embracing intelligent design, Germany can build a resilient future where indoor environments remain healthy, comfortable, and energy‑efficient. The decisions made today will determine whether the buildings of 2045 are prepared for the climate that awaits them.