Lightweight Construction – a Demand of Our Time
“Lightweight construction – a demand of our time” was the title of the article Fritz Leonhardt published in the magazine Bautechnik in 1940. Against the backdrop of the economic situation in Germany at the time – which, in view of the war that had just broken out, was strongly characterised by a lack of resources – Fritz Leonhardt considered topics such as the availability of raw materials and mass flows. He derived instructions for action for the building industry from this. These resulted in a demand for “lightweight construction”, which was consistently developed further in the decades after the war, especially in the Stuttgart School.
Careful Use of Limited Resources – a Global Challenge
The significance of the developments initiated by Fritz Leonhardt, Frei Otto and others is greater today than ever before: the increasingly noticeable consequences of global population development, as well as large-scale migration movements and the drying up of material flows, are striking challenges that lie before us all. The careful use of limited resources is a global challenge. It will shape the future of construction.
More than ever, there is a need for “lightweight construction for all” that reaches much further than before, both thematically and geographically. Characteristic of the lightweight construction of the future must be not only the search for the lightest possible construction, but also the minimisation of fossil-generated grey energy and the development of recycling-friendly construction methods.
Future Challenges for Construction Industry
Initial rough estimates of what the construction industry will have to do worldwide in the coming years, although their quality is entirely adequate, are based on the following considerations: Of the 7.7 billion people living in the world today, about two billion are children and young people, i.e. people younger than sixteen. In the coming years, these children will grow up and demand their own living space as well as their own workplace and the corresponding infrastructure.
60 Billion Tonnes
If two billion children move out of their homes within the next 16 years, a new built environment will have to be created for 125 million people every year. This corresponds to 1.5 times the total building stock in Germany. Each German citizen accounts for about 480 tonnes of building materials. If this value is used as a yardstick – and what reason could there be not to do so? – this results in an additional (!) annual worldwide demand for building materials of about 60 billion tonnes. These building materials have to be produced, transported and used (and eventually disposed of).
If we translate this hard-to-imagine figure of 60 billion tonnes of building materials into a memorable example, this shows: With the amount of building materials mentioned, a 30 cm thick wall could be built (annually, mind you!) around the equator that would be more than 2,000 m high.
Building the Future: natura mensura
The figures mentioned are incredibly high. They show vividly how great the challenges ahead are. How can building contribute to meeting these challenges? The answer could be an overarching heading: natura mensura. Not man (homo mensura), not a god (deus mensura), but nature is the measure of all things. Under this guideline, the further objectives can be outlined as follows:
- It is about creating more built environment with less material.
- It is about integrating all building materials into a recycling process.
- It is about no longer emitting gaseous waste into the atmosphere.
Design for Disassembly
Saving energy is wisely not listed as a target here, because: Mankind does not have an energy problem. Rather, it is a matter of consistently abandoning the use of energy from fossil or nuclear sources.
The consideration of the required material flows has shown that the explosively increasing demand for the built environment can only be satisfied if a drastic reduction in the quantities of materials used is achieved. In addition to minimising the resources used, the aim must also be to make these resources accessible for later reuse. Design for disassembly, i.e. recycling-friendly design and construction, is the order of the day for two reasons: on the one hand, it reduces the volume of new building materials to be obtained. Secondly, it minimises or eliminates the amount of waste that cannot be returned to natural or technical material cycles.
The changes that are necessary to make building sustainable can be named in a few words – but we are still far from practical implementation on a broad scale. Changing this state of affairs is the great future task of all building professionals.