In the Mariahilfer Straße in the middle of Vienna, MAHÜ 10-18 Vienna is building a new department store including a lifestyle hotel with an approx. 1,000 m² park on the roof. The roof park will be accessible to the public and will create additional valuable green spaces for everyone in a densely built-up and sealed district of Vienna that is severely affected by overheating. But what exactly do the buildings and their open spaces do in terms of climate resilience, sustainability and ecology?

In order to be able to answer this question precisely, the district development will be accompanied by GREENPASS in the planning and construction process, optimized and officially certified with the globally unique certification standard for climate resilience until the planned opening in autumn 2024.

GREENPASS is the world’s 1st Software-as-a-Service (SaaS) planning, optimization and certification tool for climate-resilient urban planning and architecture. The environmental impacts of real estate and open spaces are comprehensively assessed, analyzed and optimized in terms of six subject areas – climate, water, air, biodiversity, energy and costs – using 28 key indicators and 20 bonus indicators.

With the help of the international certification standard, construction projects can be accompanied from the first draft to detailed planning and implementation. The simulation-based analysis and evaluation created as part of the certification is a scientifically developed standardized test procedure for the climate resilience of buildings and open spaces. The overarching goal of GREENPASS is to sustainably improve the quality of residence, use and life in the project area and to ensure it in the long term in view of the consequences of climate change. The focus of the certification is project optimization in order to achieve the best possible climate resilience and quality of life.

Currently, the MAHÜ 10-18 Vienna preliminary draft with an overall degree of fulfillment of 75% is on the GREENPASS GOLD course. In a first step, digital simulation models for planning, the stand situation and the so-called reference scenarios worst case (no plants) and best case (very many plants) were created and analyzed with the GREENPASS software. On the one hand, this enables the planning to be compared with the existing situation. On the other hand, the minimum and maximum climate resilience is defined by the reference scenarios and the planning can be related to this. In short, it shows how well the planning works in comparison and in which areas there is potential for optimization. Overall, MAHÜ 10-18 Vienna shows a clear improvement compared to the previous situation. The key performance scores (KPS), exhaust air flow (TLS), thermal comfort (TCS), thermal storage capacity (TSS), runoff coefficient (ROS) and CO2 storage (CSS) are particularly relevant indicators or key values ​​for the climate resilience of real estate and open spaces .

The Thermal load score indicates whether the surrounding neighborhood is heated or cooled by the project. MAHÜ 10-18 Vienna cools the air on a hot day over 24 hours on average compared to the existing building. At the hottest time of the day at around 3 p.m., the many new plants cool the neighborhood by up to -0.4°C air temperature at ground level. MAHÜ 10-18 Vienna thus makes an active and positive contribution to the urban climate.

For people, Thermal comfort is the central and most important parameter for quality of stay. However, this is not about the air temperature, but a mixture of sun, wind and humidity, which we humans interpret as the so-called felt temperature, and individually depending on age and gender. The perceived temperature can be calculated from simulation data and is specified as a thermal comfort score for a project area. During the summer, the building ensemble MAHÜ 10-18 Vienna has large areas with a high level of well-being for us humans. The perceived temperature is perceived as noticeably cooler in summer due to the plants and shading on the roof terrace and ensures a high level of thermal comfort and quality of stay for future users and neighbors on all building levels and terraces.

The thermal storage score deals with the use of materials on the building and in the open space and indicates how much energy is stored in the materials. Plants convert the incoming radiation energy with evaporative cooling and thus reduce the heat load. The run-off score is a parameter for the retention or storage of rainwater and indicates how much water flows directly into the sewer system or is retained and can thus be made available to the plants for evaporation. The green infrastructures function like sponges and can store 33% more rainwater than before. Or to put it another way, a total of more than 2,500 m³ of water – as much as approx. 14,000 full bathtubs. Due to the intensive planting at MAHÜ 10-18 Vienna, 3 times more CO₂ can be stored on a typical hot day than before, therefore it has an important and valuable contribution to climate protection.

Compared to the existing situation, the sealing will be reduced by approx. 25% through the redesign of the MAHÜ 10-18 Vienna. In total, around 3,000 m² of green space will be created – more than twice as much as before! Including the combination of photovoltaics and green roofs.

Des Weiteren werden rund 50 neue Bäume gepflanzt – so viele wie normalerweise auf fast 1/4 ha Naturwald stehen – darunter auch Großbäume, die somit direkt ihre volle Ästhetik und klimatische Wirkung entfalten. Zusammen summieren sich die Pflanzen auf eine Blattfläche von ca. 2 ha – so viel wie ca. 2,5 Fussballfelder! In addition, around 50 new trees will be planted – as many as are normally found in almost 1/4 hectare of natural forest – including large trees, which thus directly unfold their full aesthetic and climatic effect. Together the plants add up to a leaf area of approx. 2 hectares – as much as approx. 2.5 soccer fields!

The project is characterized above all by the promotion of biodiversity with Animal Aided Design (ADD). In addition to local and native species, different vegetation and habitat structures, such as a species-rich herb layer, dead wood, nesting boxes as well as bee and bird pastures, are specifically used on the building.

Around 80% of the entire demolition material in the existing building is recycled. Through the use of recycled materials in gardening and landscaping or smart irrigation systems for needs-based irrigation – that is, only as much water as necessary – or smart lighting concepts to reduce light smog, the district development also takes the issue of resource conservation into account. The building ensemble also includes a district heating and cooling connection with a heat recovery system as well as intelligent shading systems for the facades. In addition to private open space, the publicly accessible roof terrace also provides and promotes socially important and barrier-free common and recreation areas.