Reusing the existing building stock: Why it’s better to convert than demolish

The arguments against tearing down old buildings and erecting new ones are primarily environmental. The remnants of materials left over when a building is demolished are usually not recyclable and therefore can’t be reused. Huge mountains of waste are generated and must be disposed of. What’s more, new buildings require large quantities of resources throughout the value chain: Raw materials must be extracted, construction materials produced and transported, and the building erected.

All this results in the CO2 emissions from the construction industry and buildings sector being far too high. The German Federal Government has set itself the target of reducing greenhouse gas emissions from building and living by at least 66 per cent by 2030 . That won’t be possible with the current levels of resource consumption and CO2 emissions: The global construction and buildings sector currently accounts for a considerable 40 per cent of CO2 emissions. In Germany, it is responsible for around 28 per cent. The energy transition can therefore succeed only in tandem with a construction transition and a new culture of converting and adapting existing buildings.

It’s worth assessing the energy consumption of a new building over its entire life cycle. It quickly becomes clear how unsustainable its energy footprint is compared to old buildings. This is because a new building involves the consumption of a great deal of “grey energy” – the energy required during the construction, production, transport, storage and disposal processes.

The exhibition Adaptive Architecture – Building Upon the Existing in Frankfurt highlights this issue. One of the projects selected by the curators is an exciting development in Brazil. A former shopping centre in São Paulo has been repurposed into a sociocultural meeting place open to everyone. Another project concerns a historic building in the Stralau area of Berlin , where an old glassworks has been transformed into 25 new homes. The history of the listed building has thereby been preserved, and new living space created at the same time.

In fact, this kind of conversion and energy renovation is often more cost-efficient, too, as a study by the Working Group for Contemporary Construction (Arbeitsgemeinschaft für zeitgemäßes Bauen e.V. ) found back in 2011. This study reveals that demolishing and building new houses in Germany is worthwhile in only about twelve per cent of cases. The campaign group Architects for Future (A4F) also sees the advantages of building upon the existing stock and is even calling for changes to the law. Its members want to see a new conversion regulation replace the old building regulations to give them greater flexibility in the planning and design process.

The buildings and construction sector has to change – and circular construction is set to play a pivotal role here. To solve climate problems, we need a paradigm shift and innovative solutions – or simply more building conversions. Material cycles must be closed in a sustainable way. That means reusing raw materials again and again or feeding them back into the cycle as biodegradable raw materials. The umbrella term for this is “circular construction”. It’s part of a sharing economy that applies the cradle-to-cradle principle . This is immensely important because only circular value chains can conserve resources.

And it’s not just the clients and architects who help to do so. During and after a renovation, everyone in the value chain can contribute to furthering the circular principle . And that goes for the interior design industry, too. Old objects, construction remains or leftover construction site materials can often be reused as interior objects. This includes materials such as roof tiles, old pipes or seals, tubes, scrap metal or waste wood. Many objects that end up in the rubbish tip could still be reused for a long time. What’s more, they give a home stylish, industrial-look accents.

Demolition and new construction are problematic for various reasons. The process consumes vast quantities of grey energy and often costs more than renovating an old property. Moreover, there are listed buildings that have social and historical value. Preservation is therefore important for our energy footprints, cost planning and urban history. The construction industry and the property sector are facing a transformation, and a paradigm shift has already begun. Circular construction is emerging as a major trend, and the cradle-to-cradle principle is being applied more frequently because of the growing demand for resource-friendly products. Used materials are reappearing in homes in the form of new interior objects. These developments are promising because they promote sustainable construction and interior decor – and they could improve energy footprints in the long run.

Are you a manufacturer who wants to stay up to date with the latest developments in the interiors industry and present your products? Then register now as an exhibitor at the imm cologne 2023 Spring Edition .