Media Release

Rescuing Raw Materials Instead of Wasting Resources. Municipal Housing Association in Munich Embraces the Circular Economy

© Drees & Sommer
Too valuable to waste: windows, doors and other components can often be reused in new building projects even after demolition. The housing association GWG commissions the environmental consulting institute EPEA to carry out a comprehensive material flow analysis for its residential portfolio in Munich’s Ramersdorf district.

Munich, May 2, 2023. Recycling thrown-out items made of glass, paper and plastic has been routine in German households for several decades. But things in the construction industry are very different. When a building is demolished, most of the individual components end up in landfill or as low-quality filling material in road construction – which is an enormous waste. The municipal housing association GWG in Munich wants to do things differently.GWG has brought the environmental consulting institute EPEA, a subsidiary of Stuttgart-based construction consulting firm Drees & Sommer SE, on board in its development area in the Munich suburb of Ramersdorf. The recycling specialists are cataloging all components and building materials, checking their suitability for reuse, and thus responding to both the shortage of building materials and the rising energy and construction prices.

Rositsa Doneva, Head of GWG’s Climate Protection team, explained: ‘The fabric of the buildings is not suitable for refurbishment. In addition, we want to create more residential accommodation and to build a total of 900 apartments in the next few years. The old buildings must therefore make way for modern buildings with optimized energy standards. However, GWG wishes to carry out a comprehensive material flow analysis which will enable it to preserve as much as possible of the original raw materials. Greatly simplified, this involves tracing the path which a substance takes from its extraction as a material and its production as a component through to its reuse or disposal.’

From a Disposal Economy towards a Circular Economy

The material flow analysis was developed by Andrea Heil and Matthias Heinrich, who are working to advance the circular construction economy and urban mining at EPEA. This is a relatively recent concept in waste management, but it could soon become a defining element in a new era. ‘We need a paradigm shift from single-use materials and waste management to a circular economy,’ said Matthias Heinrich. In the course of this analysis for GWG, the team has cataloged door frames, window glass, metal, wood and even old dustbin enclosures, and outlined their potential for reuse. The expert added: ’The construction industry in Germany consumes about 90 percent of the extracted mineral raw materials, and at the same time it produces more than half of the waste. Valuable materials are deposited in waste tips or landfill after demolition or alteration work, and almost identical materials are then purchased at great expense for new construction projects.’ GWG now wants to change this.

From Window Bars to Mountain Bike Ramps

Fundamental findings from the material flow analysis: ‘Almost all building materials can be reused, or at least recycled as high-quality materials, unless they contain pollutants. The analysis also indicates possible ways to reuse the existing components. The windows are a good example. We have 147 of them. If they meet the current energy efficiency requirements, we could easily use them again after refurbishment. If not, they can still be given a second life – for example as interior partition walls or in greenhouses,’ said Rositsa Doneva. Even more imaginative uses are possible. One example of this is the former basement window bars in the municipal library of Augsburg in Germany. They are now being used as starting ramps for a mountain bike trail near Lake Constance. This not only applies to windows. Doors, roof tiles and staircase railings are also often much too valuable to be dumped in a rubble skip, they are better placed in construction material exchange systems where they can quickly and easily find new owners.

Good for the Environment and the Accounts

Recycling construction material not only benefits for the environment by reducing the emission of CO2 and the use of resources. The reuse of materials also saves costs because building rubble is becoming more and more expensive. Disposal of a large container with five cubic meters of mixed building rubble costs up to 400 euros, whilst resale of the material actually brings in money. On average, used roof tiles can be sold for 50 cents each. Reconditioned crushed concrete sells for € 8.50 per cubic meter. A kilogram of scrap steel is worth about 20 to 30 cents. The total amount of raw materials which are contained in buildings, underground structures and roads in the whole of Germany comes to as much as 29 billion metric tons – a valuable repository of materials for the future, with the added benefit that it makes Germany less dependent on imports from third party states. ‘Moreover, these materials are much easier to use. We do not first have to process ore that is extracted from a mine, we already have the finished product,‘ highlighted Matthias Heinrich. However, the urban mining repositories do not release their raw material resources so easily.

Materials Passports for Buildings

Especially in older buildings, it is often a troublesome task to gather all of the relevant data. ‘As a rule, it is necessary to inspect everything closely on site. There are cases in which a hole must be drilled in the wall to take samples and find out what is really behind the wall,’ said Matthias Heinrich. In future, it is aimed to simplify this process by issuing a digital resources passport, which is a sort of ‘climate driving license’ for buildings. It should document exactly what products and materials are used in the building, their ecological footprint and their value. The circular economy specialists at EPEA have prepared such documentations for new buildings for several years now:  the Cradle in Duesseldorf, Germany, the high-rise residential building Moringa in the German city of Hamburg and Drees & Sommer’s new headquarters building, referred to as OWP 12 are already certified as suitable for recycling, if they are eventually demolished or altered in future. For GWG there will also be a practical guideline which will include not only urban mining, but also recycling concepts for new buildings. Rositsa Doneva explained: ‘Our aim is that the building resources passport will not be just a formality for presentation to public authorities and banks, but that it will serve to enhance life cycle management and an economical use of resources.’

Earth Overshoot Day: at the Beginning of May the Resource Balance in Germany Is Already in Minus

Such a Materials Passport is not yet mandatory, but the planned regulations will eventually force the industry to embrace the circular economy. Matthias Heinrich commented: ‘The sooner the better. The demand for raw materials and the emissions of CO2 in Germany are in the top quarter of all countries in the world. So, by May 4, 2023 we have already consumed as much in resources as the earth can regenerate in the whole year. This is a loan from the future which must then be repaid by the following generations, and this imbalance will only increase as a result of our hesitation in making environment-friendly decisions.’ Saving resources, reducing CO2 emissions, achieving climate neutrality – in his opinion these are the most important tasks of the industry for the future. This means that projects such as this GWG initiative are all the more important to set a precedent.

Pictures of the buildings for download can be found at: Pictures of existing buildings