Second thoughts on sustainability?
Our world changes rapidly. There are many views on the question which targets should be pursued now and in the future. There is confusion in international politics about prioritization. Nevertheless the conviction that “sustainability” should become a governing criterion when choices have to be made grows steadily. We want to live in clean cities, with clean air, and don’t want to bothered by too much noise. We want to reduce pollution and wish to be careful with energy. If we build structures we want to be sure that we don’t have to demolish them due to malfunctioning and that they can be adapted to new user’s demands.
The main question is how to realize all those ideas. Should we define limit criteria with regard to global warming, greenhouse gases, CO2-emission, eco-toxicity, eutrophication? Should we define limit values in building codes to avoid irresponsible use of resources? Or should we encourage and subsidize new concepts for a next generation of low energy buildings?
Repressive rules in general do not invite to creativity, although the definition of limits is unavoidable. But how should those repressive rules be formulated in order not to be misleading? As an example the image below shows a pedestrian bridge in ultra-high performance concrete built in Calgary, Canada. The ultra-high strength concrete contains about twice as much cement as a conventional concrete and is about 3 times as expensive per cubic meter. So, at first sight, this material looks at the same time non-sustainable and too costly. However, after some further reflection, this conclusion turns out to be fully wrong. Because of the high strength of the UHPC, only 1/3 of the volume of a conventional concrete is required. Furthermore no intermediate support is necessary, which increases the safety of the structure. And finally the precast long span UHPC beam can be placed in position in one night, so that weeks of traffic congestions, with corresponding large CO2-emissions, are avoided. In addition the structure is elegant and hardly requires maintenance. So, this shows that a judgement on the sustainability of the structure should not be limited to the properties of the structural material per unit volume, but should consider the project as a whole, considering as well its role in the city infrastructure.
Another challenge to develop creative sustainable ideas is related to the question of how to deal with energy resources. Experts have stated that we waste roughly 98% of our energy. In just one hour, the earth receives more energy from the sun than the entire world could ever consume in a year. This triggers smartly combining functions, as was demonstrated by TUD architecture students in 2011, see image below. They designed an “Energy wall”, which enables the combination of a number of functions (including mobility) in an urban area. The length of the wall is 1 km. It is equipped with solar cells and wind turbines. It includes a LED lighting system and functions meanwhile also as a noise barrier.
This demonstrates that we do not only need sustainability limits to control harmful threads like global warming potential, the emission of CO2 and greenhouse gazes. Most of all we need people who are creative and able to “think out of the box”. Especially young people are predisposed to generate new and creative ideas. They have the advantage of not yet been too much programmed by fantasy-reducing education and experience and are not afraid to move frontiers. Moreover they are motivated to think about their own future and that of the generations coming behind them.
So, we have plenty of reasons to wish the the participants of the S-CO2DE competition a lot of inspiration and look forward to their ideas!
