It is impressive that in 2024, 83.1 percent of the Federal Republic of Germany’s land area was used for “green” purposes. Germany’s total land area is 357,700 square kilometers, or 35.8 million hectares. The 14.6 percent used for settlement and infrastructure is negligible in comparison. Or does it?
Soil sealing continues unabated
Between 2019 and 2022, 52 hectares of green space were needed annually in Germany for settlement and transport purposes. This meant that the German government’s target of converting a maximum of 30 hectares per year by 2020 was far from being achieved. As a consequence, the conversion rate is to be less than 30 hectares per year by 2025 (source: Federal Environment Agency). Calculated over a period of ten years, that would be just 300 hectares, a negligible amount compared to 35.8 million hectares – or is it?
Overheating of cities, even small green zones can help
With climate change accelerating, cities have been getting steadily warmer in summer for years. Four-lane main roads and large parking lots, together with building facades, are ideal heat reservoirs that make it almost impossible for temperatures to cool down even at night. In contrast, 40 percent green space reduces heat by 50 percent (source: Pflanzenforschung.de).
Urban densification also offers a certain degree of green space protection. This term has been haunting the media for some time now and means nothing more than optimizing existing buildings instead of designating new building land. The discount supermarket chain ALDI implemented an interesting idea in this regard a few years ago. If land is used for a supermarket, an apartment building can also be built on top of it – the square meters of building land required remain the same.
Gardens of horror: The difference between rock gardens and gravel gardens
Homeowners who let gravel thrive in their gardens instead of lawns and flowers, colloquially known as gardens of horror, were in a veritable battle against green spaces. While a rock garden certainly adds a touch of greenery and is water-permeable, gravel gardens are gray and easy to maintain. To ensure that no greenery could penetrate, the subsoil was sealed with plastic sheeting. And that was precisely the illegal problem for the owners long before the municipalities banned this type of garden design. “Because all state building regulations state that undeveloped areas of built-up properties must be designed to be water-permeable and must be greened or planted.” (Source: nabu.de).
Green spaces produce the air we breathe
The following examples illustrate why the topic of “green space,” i.e., fields, forests, and meadows, is so immensely important and why 30 hectares of conversion per year is not a negligible figure.
One hectare of deciduous forest produces 15 tons of oxygen per year. One hectare of coniferous forest produces twice as much, at 30 tons (source: Bavarian State Forests). 30 tons of oxygen—how much is that, and how much of it do I need right now? Fans of gravel gardens should bear this figure in mind: 250 square meters of lawn behind the house produces as much oxygen in a year as one hectare of coniferous forest, 30 tons. This is the amount of oxygen needed by a family of four, 7.5 tons per person per year (source: Rollrasen-Tirol).
In other words, the conversion of the targeted 30 hectares of meadows or forest into residential or traffic areas robs 4,800 people of oxygen for one year (meadow or coniferous forest) or 2,400 people (deciduous forest).
This puts a whole new perspective on new highway sections or urban densification as alternatives to expanded building land.
