Many thousands of studies have been published on global warming since the mid-1970s, and the vast majority (around 97%) support the scientific consensus on climate change. Since the beginning of the weather records, the ten hottest years all fell into the period after 1997, and there is no other plausible explanation for such an accumulation of high-temperature phases than the greenhouse gases emitted by humans. Even the more climate-sceptical US Department of Defense classifies climate change as a growing threat to national security and fears that natural disasters, streams of refugees and the fight for scarce resources such as food and water will lead to global conflicts. For the United Nations, climate change is the greatest systemic threat to humanity. 71 percent of all Germans fear climate change more than wars, terrorist attacks or poverty in old age.
But instead of stepping on the brakes, mankind is shifting up a gear: after three years of stagnation, global emissions rose again for the first time in 2017 – to an all-time high of 32.5 thousand million tons. And that's not all. The USA (16% of global CO2 emissions), the second largest climate sinner after China (28%), has revoked the Paris Climate Pact. And Germany (2.36%) has also become the EU's biggest climate sinner. The 148 coal-fired power plants that are still connected to the grid and export their surplus, dirty electricity abroad account for the largest share of local CO2 emissions, although their output has long since been compensated by renewable energies. The government finds it difficult to assert itself against the lobby of the established energy industry. They want to earn as much money as possible with their old business model. Like the automobile industry, which clings to the dirty combustion engine with unclean tricks instead of advancing the clean electric drive.
The construction industry is a major contributor to climate change. It accounts for almost 40% of global final energy consumption and 20% of CO2 emissions. It consumes 50% of the world's resources and produces 50% of its waste. This results in an enormous responsibility. Climate protection in the German construction industry focuses mainly on the legally prescribed energy saving and efficiency of buildings. But after the initial successes, I now see a clear reluctance to reform in the industry: "Why don't you take a break with climate protection?” Unbelievable in the face of the real threat. And the legislator continues to attach great importance to the topic of thermal insulation. Higher environmental regulations for buildings make a significant contribution towards climate protection, but also make construction more expensive. Against the background that socially responsible living in conurbations has become a scarce commodity, some are asking whether the price paid for environmental protection is not too high. The current Energy Saving Ordinance (EnEV), for example, increases the construction price per square metre by around 100 euros, but the additional energy saving potential thus gained only amounts to a meagre 0.02 %. A rethinking is necessary. Regenerative heating systems (environmental heat, biomass and solar energy) can help here.
But affordable housing versus environmental protection is a misleading conflict. If environmental regulations are relaxed, the climate tilts. If there is no affordable housing, society tilts. Considerable efforts must continue to be made in both directions. And there is still plenty of room for innovations and significantly better solutions. For example, 75 % of all heating systems in Germany are more than 20 years old and no longer correspond with the state of the art. Modern heating technology alone could reduce building energy requirements by 13 %. However, this potential is not exhausted because around 11 million outdated low-temperature heatings are exempt from the replacement obligation as prescribed in the EnEV.
A frightening waste of high-quality resources may still be observed on construction sites. And then many things are glued together in such a way that no one will be able to separate them later. Most of what is being recycled in the construction industry is no more than energy-intensive waste disposal. Cables and glass are melted down, stones and screed shredded, roof trusses and formwork are burned. A tragedy.
Grey energy is an almost unnoticed quantity in the climate balance. This is the amount of energy required for production, transport and disposal. It is the ecological luggage that every building carries with it. For example, the production energy requirements of some low-energy and passive houses are considerably higher than their total heating energy requirements. This is mainly due to components that are manufactured in numerous energy-intensive conversion steps. The more a building material is processed, heat-treated or chemically modified during its production, the worse its ecological footprint becomes.
The EU research project "Buildings as Material Banks" (BAMB) gives rise to hope. By 2021, 15 European companies, research institutes and universities want to develop a so-called material pass for new buildings and conversions. The aim is to avoid waste completely over the entire life cycle of a building and to reduce significantly the consumption of natural resources. It is intended to help ensure that the recyclability of building materials is already integrated into the construction process in the planning phase and that they are reprocessed at the end of the life cycle and reused in the same quality. The material pass thus creates the necessary transparency to establish a genuine recycling economy in the construction industry. But even without a material pass it is already necessary today to use building materials in such a way that they can be reused in the highest possible quality.
André Le Nôtre did not yet know of any climate change. But when part of the 11th James Bond film Moonraker was shot in Vaux-le-Vicomte in 1979, the scientific view that the earth was heading for disaster was just gaining ground. In the film, Roger Moore saves the world's population from a poison gas attack from outer space. In the real world, billions of people need to cooperate and change their behaviour. It's not too late yet.
