Market Overview: Heat in Urban Areas and its Consequences

Sustainability starts with the right choice of location

Dear Readers

Recent summers have been marked by prolonged heat waves, drought and extreme weather conditions such as violent thunderstorms, heavy rain and flooding . The experts at the German Meteorological Service and other climate researchers agree: such extreme weather conditions will become more frequent , as the consequences of climate change will also become increasingly visible in Germany.

In particular, heat in urban areas and its consequences are – in addition to global warming – a result of dense construction and the decision to reserve and seal public spaces for traffic and parked vehicles. According to the Federal Environment Agency (2021), around 45 per cent of residential and transport areas in Germany are built on, concreted, asphalted or otherwise paved. This means that water can no longer drain away and the risk of the formation of local thunderstorm clusters, which are difficult to forecast, increases due to the high level of evaporation. In addition to the environmental consequences , the heat also has a negative impact on the health and quality of life of city dwellers.

Urban green and water spaces, on the other hand, result in cooler cities. Temperatures in inner-city areas are thus reduced by several degrees, which ultimately also leads to a higher quality of habitation, work and life. Green spaces allow more water to drain away and result in higher soil fertility.

Real estate players should therefore focus holistically on sustainability and make their investment decisions accordingly. This begins with the right choice of location and an assessment in the urban ecological context. In addition to the analysis of classic location factors, this requires further data and information on the so-called green and blue infrastructure, such as residential density, sealing ratio and green and water ratios in relation to the total urban land area, but also in relation to the micro-environment of a property.

But which cities have a high population and building density?

But which cities have a high population density and therefore also a high building density? Which cities, on the other hand, are particularly green and offer better protection against heat and floods and a better quality of life?

So far, there has been no official recording of soil sealing at the municipal or city level. A simplified formula established by the Länderausschuss für Bodenschutz (LABO) (Federal Committee for Soil Protection) can be used as an indicator: „The more densely populated the area, the scarcer the space and the more intensive the development and sealing of the areas used.”

The degree of settlement could first be determined with the help of population density (inhabitants per km² of area). Accordingly, among all A, B and C cities, our capital Berlin is the least densely populated, while the C city Erfurt – small and compact – has significantly more inhabitants concentrated in its total area, as the following overview shows. Based on this, we could suppose that smaller cities with compact layouts have a significantly higher proportion of built-up and sealed area, as can be seen in the example of Erfurt, than large cities with more space, such as Berlin, Hamburg or Munich.


However, the LABO’s simplified formula does not seem to be applicable in all cases on closer examination. The breakdown of the municipality-based land use survey by type of actual use shows that even very densely populated cities have a large proportion of green spaces and that the amount of land used for construction does not necessarily correlate with the settlement or population density.


Thus, residential, industrial and commercial areas can be concentrated in only a small area of the total area, while forests, parks, agricultural areas and other vegetation are nevertheless sufficiently available. Good examples of this are Stuttgart, Offenbach, Karlsruhe or Mülheim an der Ruhr. Overall, C-cities are significantly greener than A- and B-cities.

Ranking of the A, B and C cities according to
the proportion of vegetation and water area

Are major cities losers in the long term?

From an ecological point of view, however, it is precisely our major cities such as Berlin, Hamburg or Munich – which are not currently very „green“ and are also expensive in terms of purchase prices and potential returns – that could be among the losers in the long term due to their dense development. Especially as they have to opt for further densification and extensive construction due to the pressure of demand – especially on the housing markets – and thus increase land consumption and sealing. This also means that the greener a city is, the more likely it is to become attractive in the long term as a place to live, but also as a place to work, which could ultimately have an impact on land and property prices – especially on the housing market.

I would personally like to make an urgent appeal, not only in times of extreme heat: our cities must become greener!

With this in mind, the IZ-Research-team and I wish you a great summer!

With best regards from
Ingeborg Maria Lang


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