Leading software for high-resolution 3D modeling of urban microclimate to analyze the impact of buildings, vegetation, etc. on the urban climate with the aim of planning climate-friendly cities and improving the quality of life in metropolitan areas - designed for professional use by architects, landscape architects, urban planners etc., as well as for research at universities.

Innovation City Bottrop

Air pollution from nitrogen oxide (NO) and nitrogen dioxide (NO₂) has become one of the largest air quality problems in urban areas, with many cities worldwide exceeding recommended concentration limits. Except for removing traffic with combustion engines, there are very few options to reduce NO and NO₂ pollutants in urban areas. This project investigated the effects of photocatalytic surfaces on the local pollutant level.

One of the passive strategies to lower NO, NO₂ and subsequent near-surface ozone in urban areas is the use of photocatalytic active surfaces. These surfaces, containing titanium dioxide in the materials or paint, are able to absorb NO and NO₂ from the air and transform it into a solid nitrate which can be washed away with the rain.

The effect of this pollutant removal on local air quality was investigated using the ENVI-met passive and active chemistry model that includes the NO-NO₂ – ozone reaction cycle.

The Innovation City Bottrop Project was a large think tank and demonstration project in the Ruhr area with STEAG Power Minerals and TU Berlin. The ENVI-met team investigated the potential of using photocatalytic surfaces (ground surface and facades) to reduce the NO and NO₂ levels.

Several simulations were performed for the inner-city district of Bottrop using different meteorological scenarios and varying levels of active surfaces initially using the PHOTOMENT material from STEAG Power Minerals. In later project phases, different materials using KRONOS titanium dioxide were investigated.

The results of the ENVI-met simulations showed a local reduction of 5 % to 14 % NO and 4 % to 6 % NO₂ could be achieved using this passive technology, depending on the level of active surfaces and of the traffic NO𝗑 load.


STEAG Power Minerals, Dinslaken, Germany

KRONOS International, Leverkusen, Germany

Implementation period

First phase 2013, several following phases

Used features

ENVI-met pollutant dispersion model

Active chemistry model