Timber achieves rapid growth in Vienna

Over the past months, commuters have been able to witness building work progressing at Obere Donaustraße 23-27 while driving past in their cars. Here in Vienna’s 2nd district, “Europe’s first urban quarter built with timber” – which is how UBM Development describes their project LeopoldQuartier – is currently being constructed at an extraordinary speed. Once finished, approx. 23,000 square metres of office and living space will be newly available. Remarkably, the nine-storey shell of the office building was in place only ten months after the groundbreaking ceremony. Shooting upwards in the shop window of one of Vienna’s main road arteries, as it were, in future the building will shield the apartments behind from the sound of the traffic.

The short construction time has even surprised the project developers. “As this timber hybrid building is actually a pilot project, we allowed slightly more time for the initial construction phase. And since prefabrication of the timber construction elements was completed more quickly than anticipated, we are now ahead of our construction schedule,” says UBM project manager Martin Mann.

Developed in dialogue with local residents

Three of the five project sections are already at full height, and there is still no sign of any oppressiveness that is frequently encountered in new urban quarters. This sense of airiness is created by the degree of construction density at roughly 50 percent, which leaves enough space between the structures and also for a central park with play area. As Martin Mann explains, the decision to make the whole quarter entirely free of cars was essential for this design. Parking spaces have been moved underground, with only the emergency services and waste disposal trucks being allowed inside the quarter itself.

This “green zone” in the central courtyard was one of the key concerns during the public participation process, which has become a vital part of such projects today. Mann is convinced that “to ensure maximum satisfaction once the project is completed, it is crucial to integrate all the various players in a city’s fabric.”

Therefore, in March 2020 the City of Vienna organized a two-day “info exhibition and dialogue event” on the LeopoldQuartier. Feedback from the citizens who attended was ultimately incorporated into the specifications for the urban development competition.

Urban redensification with timber

However, it is not just the future residents and users who will benefit from this new development, which will provide 25,400 square metres of office space, 500 new flats and an apartment hotel at the heart of the city. Urban redensification is also among the effective ways to counteract the painfully high land consumption in Austria. Where empty office buildings, parking spaces and a multi-storey car park once occupied valuable urban space, people will soon work, live and play.

In the case of the LeopoldQuartier, redensification is being achieved with a timber hybrid design which benefits the carbon footprint of this urban development project in two respects. Firstly, production of timber construction elements causes much less carbon dioxide. And secondly, timber construction is regarded as an effective carbon sink because one cubic metre of wood locks up about 1 tonne of carbon.

This means that the entire quarter – with its approx. 11,000 cubic metres of timber used for building – will store around 11,000 tonnes of this harmful greenhouse gas over the long term. As these numbers are difficult to conceive, the project manager provides a comparison in layman’s terms: “The amount of carbon stored in the timber used for the LeopoldQuartier corresponds roughly to the annual CO₂ emissions from a village with 1,250 inhabitants.”

The path to sustainability initially required considerable powers of persuasion. “But now it is great to see everybody forging ahead together,” observes the project manager. Unlike conventional construction methods, building with timber requires much more extensive and improved forward planning. “Prefabrication of the timber construction elements with pinpoint accuracy uses a digital twin as its basis, with every power socket and every cable outlet specified from the start. This results in not just greater efficiency during the building process, but also high construction quality.”

Self-sufficient with geothermal energy and solar power

While the City of Vienna is currently working on tapping into thermal water at a depth of three kilometres to provide emission-free district heating for the young urban quarter Aspern, the energy supply at the LeopoldQuartier is even more local.

Vienna’s new neighbourhood has its own geothermal power plant with photovoltaic system that supplies green energy. “This makes the entire quarter energy self-sufficient and independent of fossil fuels,” says Mann.

The office building and the first 75 apartments are scheduled for completion at the end of 2025. But the Obere Donaustraße will serve not just as a showpiece for sustainable construction. The City of Vienna is also planning to change the traffic system here, and increase the potential for green mobility. The road outside – which is the only three-lane section of this traffic artery – will soon be reduced to two lanes, with the new area offering more space for cyclists, pedestrians and trees.

Text: Gertraud Gerst
Translation: Rosemary Bridger-Lippe
Photos: Philipp Horak, UBM Development