• Photo by Franck V. on Unsplash

In times of the coronavirus we all stay more at home much more, mobility becomes immobility. Immobility can also be sustainable. The City of Hamburg is trying to prove that, in a different way, then you might imagine at first. Let me present two interesting projects to you.
Part I: green.fACade, the air-cleaning building facade

The air quality is too poor

We all know the story about the poor air quality in our cities, particulate matter and nitrogen oxides pollute us more and more. Among the main culprits for the poor air quality are diesel vehicles, which have since been banned from the centres of some German cities. The German Federal Minister of Transport and Digital Infrastructure, Andreas Scheuer, brought the issue back into the headlines at the end of April when he identified a mismatch between the lower traffic volume and various nitrogen oxide measurements and questioned the diesel driving ban. The background to the statement was that despite the significantly less road traffic in the corona crisis, nitrogen oxide values at some measuring stations were above the limit value, although the opposite should actually be the case. There are numerous explanations for this:

Nitrogen Oxides and particulate matter are mainly produced by road traffic and by the combustion of fossil fuels, but not only by this. There are also natural sources such as soil particles, pollen or fires, and dry weather can also contribute. So even the smallest soil particles are whirled into the air when there is a strong wind. At the beginning of April, additionally, east winds brought very dusty continental air to Germany. And in spring, agriculture also receives a lot of fertilizer, which also affects air quality.

Hamburg as a Pioneer

It should, therefore, be noted that there may be other reasons for the poor air quality besides road traffic. Consequently, there must be other ways of improving air quality either, then just banning diesel vehicles from the city. After Hamburg was the first German city to have a ban on diesel driving in April 2018, the Hanseatic City is now also working on alternative solutions and showing that there can be immobile measures to improve the air quality.


In the summer of 2018, researchers at the RWTH Aachen University presented an innovative and adaptive textile facade. The so-called green.fACade reduces nitrogen oxides in urban areas and can be attached to a building like a second skin. A titanium dioxide coating of the green.fACade acts as a photocatalyst and oxidizes the nitrogen oxides (NO and NO²) to form washable nitrate (NO³-). Since the facade is also greened, it contributes to the conversion of carbon dioxide into oxygen through photosynthesis.

green.fACade is part of an innovative research project Adaptive Textile Facades and belongs to a research series with the aim of developing new types of facade construction that are climate-neutral and increase the comfort of residents. The Adaptive Textile Facade acts completely independently and reduces energy consumption through the positive climate effects on the building facade.

The world’s first NOx-binding building facade

In February this year, such an adaptive textile facade was world-wide first installed on a building, and Hamburg is once again the Pioneer. ECE-Projectmanagement, a company active in the real estate industry, now has the world’s first building facade that binds nitrogen oxide. For a total of 90,000 euros, a 22-year-old office building on the ECE campus was newly clad. The building is located directly next to the busy and nitrogen oxide-polluted Ring 3 in Hamburg and is expected to provide valuable data on the effectiveness of the novel technology.

Complex measuring procedures with digital measurements technology on the facade enable live monitoring, for which a further 24,000 euros were invested. The result of the project shall provide information on the contribution of the facade to improving air quality. The effects on urban space as well as on the interior of the building will be measured.

Nanosize titanium dioxide

The titanium dioxide used in the new adaptive facade comes from the inok Ltd., which has succeeded in reducing the individual particle size to seven nanometres. In general, the smaller the individual particles, the greater the effect. Titanium dioxide has already been sprayed onto roads and curbs in some Japanese cities for several years, which has led to a reduction in nitrogen pollution. But the titanium dioxide reacts with organic substances, which in the long run reduces the effect and sometimes attacks the surfaces.

The now successful reduction of the titanium dioxide particles to nano-size makes it possible to incorporate them into a liquid for completely contactless coating of surfaces. This means that the titanium dioxide can no longer react with other substances and the effect is significantly extended. This opens up new application possibilities, for example on building facade.

I am curious to see how the project will develop further and how many more new-skinned buildings we will see in our cities…