In Germany, the urban housing shortage is increasing, but so is the climate catastrophe. To solve both, we need a paradigm shift in urban planning - without cement and new buildings.

In December 2020, Triodos Bank joined a broad alliance in Germany to make a joint call urging the German government to increase climate protection in the building sector. Because no matter how sustainable new buildings may be, in most cases it’s better not to build new ones and to rethink the use of existing buildings instead. But that hardly ever happens.  

Manuel Ehlers, head of sustainable property at Triodos Bank Germany, has his own ideas about this issue. 

When it comes to the question of a sustainable and ultimately climate-neutral city, there is one central aspect that has been almost aggressively hushed up in the past: building in the same way as in recent decades is very harmful to the environment. Fortunately, however, this information is now getting through to wider sections of the population. Emissions from the construction sector account for 38% of global energy-related CO2-emissions. It can be assumed that 50% is caused directly and indirectly by the construction sector when infrastructure measures such as bridges and roads are included. 

In Germany, too, buildings are one of the largest emitters of CO2-emissions: the production of building materials alone accounts for about 8% of Germany's greenhouse gas emissions, which is equivalent to the average annual air travel of all Germans. Cement, for example, is a real climate killer; its production is responsible for 8% of global greenhouse gas emissions and it is also poorly recyclable. Furthermore, the construction industry in Germany generates more than 230 million tonnes of construction and demolition waste annually, which is more than 50% of the total amount of waste generated. 

Put simply, conventional building with concrete and steel is not compatible with the concept of a climate-neutral city. Cities all over the world are growing at an incredible rate - but where are all these people going to live? This question has considerable social implications. In Germany, too, housing construction has long since become a matter of federal policy. The current coalition agreement states that 400,000 new homes are to be built annually. What is surprising about this is that, statistically speaking, an excess number of 172,000 homes were built in 2018 alone. This is because, whilst the population increased by 227,000 - requiring 113,500 new housing units - as many as 285,900 new homes were built during this period. This seems a blatant contradiction for all those people searching in vain for affordable housing. 

Anyone who claims that this does not apply to metropolises should face up to the following statistics: in 2018, the city of Berlin grew by 31,300 inhabitants, for which statistically 15,600 new homes were needed - but no less than 16,706 new homes were built. By 2021, the German capital had grown by around 13,400 inhabitants and yet permits for almost 18,800 new homes were issued. 

But the real estate sector continues to proclaim the mantra: ‘Build, build, build'. The demand for more new construction follows the macroeconomic pattern that price (i.e. rent) will regulate itself if the supply is sufficient - but this equation is already no longer valid, due to inappropriate use in environmental protection areas, Airbnb and speculative vacancy. 

The constant demand for new buildings is therefore naive in response to lobbying - and ignores the question of the planet's survival. Land is not a commodity that can be increased at will - certainly not in Berlin districts like Friedrichshain-Kreuzberg. Building takes time - a home that is needed and in demand today will only be ready for occupation in two or three years' time. Building in its present form usually ignores the question of what is to be built, for whom and by whom - and above all, in what way. Meaningful answers to these questions come neither from politicians nor from the construction industry itself. If you look more closely, you will find the first signs of new approaches in citizens' initiatives or associations such as the ‘Immovielien’ network platform for public welfare actors on the issue of building’. 

The real estate sector fails to understand sustainability as a future-oriented, holistic action that takes life-cycle costs into account but sees it rather as 'business as usual', perhaps supplemented by new, so-called 'smart' technologies. However, our CO2-credit has long been used up. 

To meet the 1.5-degree target with 50% probability, Germany could still achieve 4.2 gigaton CO2 emissions between 2020 and 2050. This corresponds to 1% of the total share and reflects the population share. Currently, however, Germany is still at 2%. Assuming that the share for high-rise activities is 10% of the remaining budget, approx. 350 million tCO2-equivalents could be consumed. This means that the 1.5° budget would only suffice until 2034 if we continue to build as we do now (25.4 million tCO2/year). 

If we take sustainability seriously, the climate targets cannot be met with new smart technologies, but almost exclusively with drastic reductions. In Germany, the average living area is 46.5 square metres per capita - and the trend is upwards. This raises the question of sufficiency and whether this is the right development. Undeniably, the most sustainable way to build - and everyone should agree on this – is not to build. Incidentally, it is also logical that the rent in an existing building is lower than the rent payable on the same site in a new building, since the latter has to bear the costs of both demolition and new construction. Applying this logic, there should be a general ban on demolition. 

In addition to current energy consumption, we must also consider life cycle costs 

We need to take a holistic view of real estate and consider not only the current energy consumption of a property, but also its life-cycle costs and CO2-backpack that conventional construction entails - from construction to demolition, the so-called ‘grey emissions’. The CO2-emissions from the production of building materials are almost always ignored, a practice facilitated by the fact that there is still no meaningful pricing of CO2. At the same time, about 11% of global emissions are now caused by the production of building materials. 

In 2020, for Germany this amounts to the equivalent of 54 million tonnes of CO2-equivalents, 44 of which were due to new buildings and 10 to renovations. It is interesting to note that with these emissions, almost as much of the surface area is newly built as is remediated (55 million m² compared to 49 million m² per year). Decontamination therefore has a clear emission-related benefit. 

Assuming a realistic price for CO2 in the form of a CO2-tax of €180 per tonne, as advocated by Scientists for Future and others, would almost double the final price of concrete for example. 

So, the question is economic, ecological and cultural: what if there were a ban on demolition? The fact is that we must work with resource-saving, local, renewable materials - first and foremost and as far as possible from a construction and fire safety perspective with wood, loam and hemp. One scenario that manifests itself because of a demolition ban combined with a sensible post-growth society is, for example, a landscape of diverse empty shopping centres. Simply demolishing them would certainly be a great relief for many critics of mass consumption - but at the same time, they are a valuable memorial to a consumer society that we have narrowly escaped. 

Empty shopping centres as aquaponic locations 

These empty shopping centres could be put to wonderful use, for example by being converted into vertical greenhouses and aquaponic systems (vegetable cultivation in soil-free water systems, which is already practised on a large scale in Tel Aviv, for example). Without long transport routes, they could then supply the city with food. Communal gardens can be planted on the roofs, which could also provide meeting places and additional green spaces in the city. Thus, the city would gradually become a green oasis that is even capable of making a positive contribution to climate protection. 

A good example of how a start is already being made to re-use centrally located and under-utilised spaces is the car park in Ring-Center 2 in Berlin. Here, on the upper parking deck, which is hardly ever used by motorists, they have built a 152-room hotel with modular wooden construction. In this way, a derelict site in the city centre has been repurposed and densified. Furthermore, it uses a building method that is climate-neutral or even better, thanks to the materials used in its production: wood from sustainable forestry stores more CO2 than is produced through processing and transport. 

Another example is a project in which in an empty industrial building in a southern district of Berlin earmarked for demolition has been redeveloped to house more than 60 artists' studios. Directly opposite, an existing building was demolished to build a logistics hall for a large mail-order company. Here, couriers, with precarious working conditions, drive back and forth in their diesel-powered vehicles to deliver goods ordered on the Internet to the city within a few hours. In common with the development of new shopping centres in Berlin, this is a very questionable development that goes completely against the utopia of a climate-friendly city, short distances, and local production. 

A demolition ban would not only enable us to sustainably reuse abandoned shopping centres and put them at the service of urban society, but would also prevent the production fantasies of investors from being further fuelled. The fact that land prices in urban agglomerations are constantly reaching new heights is also due to the continuous fulfilment of yield promises and the densification of urban space with high-rise buildings, micro-apartments, or capsule hotels. 

Finally, rural areas would also benefit: the potential of empty or underused buildings is huge. Once the infrastructure is intact and the fibre-optic connection is in place, completely new opportunities arise - all to protect the climate and prevent unnecessary new construction in conurbations.