Sustainability in building materials gets more and more important, since rar materials are becoming scarcer. On the one hand, this is due to a worldwide construction boom: The supply of building materials is currently not keeping pace with the permanently increasing demand. According to the law of supply and demand, building materials are therefore becoming massively more expensive. But there is another, far more worrying reason for the shortage of building materials: resources are running out. The global economy must therefore radically rethink its approach – and focus on sustainability. Sustainability is the only way to ensure that raw materials will continue to be available in sufficient quantities in the future.

Sand as a building material does not exist “like sand on the seashore”

Take sand, for example: As an aggregate for concrete, sand is in such high demand that the phrase “like sand on the seashore” as a synonym for abundance has long since become obsolete. Every year, 40 to 50 billion tons of sand are consumed. Sand mining has massive consequences for the environment along rivers and coasts. In the large sand deserts, where according to conventional opinion there should be enough sand, this building material resource cannot be extracted: The desert sand has no edges because the wind grinds the sand grains around. As a result, the individual grain of desert sand lacks the ability to bond with other grains. This, in turn, is the essential property that makes sand so valuable – and so indispensable – for concrete production.

Construction waste can be broken down into individual parts

Once sand has been “poured into concrete”, it would thus be “used up” for good: this is also a common opinion. But far from it: building material recycling is the keyword here for sustainability. Building rubble has long since ceased to be a waste material for landfills. It can be crushed and broken down into many individual components. Demolition companies can recover new sand from old concrete. The Heinrich Feeß company from Kirchheim/Teck – already awarded the German Environmental Prize in 2016 – is one of the pioneers when it comes to producing new, high-quality building materials from demolition material: by screening, sorting and washing.

Recycle and reuse concrete as locally as possible

Recycled materials – which help to reduce the consumption of primary raw materials by sustainable circular economy – cannot prevent the worldwide continued exploitative mining of resources, such as sand. But it is an important step in the right direction to increasingly rely on recycling for building materials as well. This avoids – ton by ton – negative environmental impacts at the extraction sites worldwide. And it also saves the CO2 emissions caused by the long transport routes. Sustainability at its best in this case would be to demolish concrete and recycle it as locally as possible – in order to reuse the recycled materials for new buildings as locally as possible. This would be an important “building block” for achieving climate targets and preserving the earth for future generations.

High-quality secondary raw materials

It is not only resourceful entrepreneurs and scientists who are needed to further expand the recycling of construction waste. Politicians are also called upon to set the course for prescribing this type of sustainability in legislation. It is also a matter of re-evaluating the quality of recycled concrete. Up to now, recycled concrete has still been regarded as inferior by many architects and builders. However, this fear can be brought under control through quality assurance regulations: If demolition and recycling companies are steered by appropriate legal requirements to produce and sell only demonstrably high-quality recycled products, these secondary raw materials will often be in no way inferior to primary raw materials.

A lobby against the recycling of building materials

The manufacturers of primary raw materials, however, still seem to be causing difficulties: They fear the increasing competition from recycling. They are therefore trying to increase or at least maintain their own profits at the expense of a sustainable recycling economy that makes sparing use of the world’s finite resources. With their attitude, they also exert influence on politicians to prevent laws that would strengthen sustainability.

The most important facts in brief

  • The global shortage of resources is a major problem. In the long term, only sustainable thinking can help. Construction waste, for example, can be separated and recycled.
  • Recyclable building materials are coming into focus: Those who reuse demolition materials slow down the increase in the extraction of new raw materials. Policymakers must therefore define quality requirements for recycled concrete. In addition, the local reuse of recycled material can save large amounts of CO2 because long transport routes are eliminated.
  • CO2 emissions are also a major problem in the production of cement. Here, the industry must optimize its processes in order to release less CO2 in the future for the same quantity of cement.
  • Ecological building materials made from renewable raw materials promote sustainability. Sustainability is also a task of architects when thinking about the future demolition of a building in the planning process – in order to be able to recover the most valuable secondary raw materials possible from the future rubble.

The cement industry produces extremely high levels of CO2

CO2 emissions are not only a disadvantage when transporting sand over long distances – often halfway around the world – but also in the production of cement, another important component of concrete. Although cement plants have become much more environmentally friendly in recent years, the cement industry worldwide is still four times as high in CO2 emissions as air travel – also worldwide. This does not mean that the “ecological footprint” of the individual “frequent flyer” does not play a major role in view of these dimensions. Rather, the point is that cement manufacturers worldwide must also work to optimize their processes in order to further reduce their CO2 emissions. These emissions will remain high because the production of cement basically releases carbon dioxide that would otherwise remain bound in lime.

More ecological building materials

Accordingly, ecological building materials such as wood, cork, clay, bricks or even insulating materials such as hemp, jute, wood wool, wood fiber and coconut fiber are preferable to concrete containing cement. Wood and cork in particular have the advantage that they are renewable, i.e. sustainable in every respect. However, care must be taken to ensure that the wood, as already shown in the example of recycled construction waste, also grows as close as possible to the area in which it is consumed. The disadvantage of long transport routes – in terms of CO2 emissions – remains the same whether sand or wood is transported. However, the decisive factor for sustainable building materials is always whether they can be reused.

When building, the later demolition must already be carefully planned

If possible, reuse must already be taken into account during construction: Apart from the pyramids in Egypt or medieval cathedrals in Europe, rarely anything is built “for eternity”. In many construction projects today, builders and architects assume a “life expectancy” of their buildings of between 50 and 100 years. Many houses fall victim to the wrecking ball after just 20 to 30 years. So anyone who ensures from the outset that the materials and their connections can be easily disassembled, separated and recycled in the event of subsequent demolition is acting in a similarly sustainable manner to someone who replaces concrete walls with wooden walls. This, too, is becoming part of the “smart city”.

To meet climate targets, CO2 reduction must become a focus across industries. Since the construction industry is responsible for a significant share of CO2 emissions compared to other industries – the sector now accounts for 38 percent (9.95 Gt CO2) of global CO2 emissions according to the 2020 GLOBAL STATUS REPORT FOR BUILDINGS AND CONSTRUCTION – we at magility are keeping a wary eye on developments in this sector. Feel free to contact us if you have any questions about the latest developments and trends in this area. We help companies in the construction industry to adapt their business models so that they can operate in a way that is both economical and climate-friendly.