Sustainability

A world where we live in cities with buildings made of earth already exists. And they are actually located in the global south. The various earthen cities of Yemen have been featured in numerous documentaries and articles. The old town of Sana’a and the city of Shibam are both part of the UNESCO World Heritage. With earthen skyscrapers, many of which are hundreds of years old. These cities are still inhabited, functioning places with buildings, that are very well adapted to the local climate.

Here are some drawings of these buildings. Another famous example is the Tulou residential buildings in the Chinese region of Fujian. These multi-storey, usually circular buildings, some of which date back to the 12th century still stand today and are still in use. The outer round wall is made of a 1.5 metre thick rammed earth shell, while wood or brick was used for the inner part. Some of them can accommodate up to 50 families.

Essentially, it is a perfect example of a residential building with very high earthquake safety, which is mainly achieved through the very thick walls and the round shape that it has. A type of housing, that could still function very well today. Of course, there are many challenges, to promote this or similar alternative building methods further, legal requirements, technical hurdles, increase in climate change-related floods and fires. Moreover, these structures are not cheap and require expertise that is not available everywhere. But what is probably even more challenging is: living in such cities would require a rethink in our lifestyle and in our relationship with the built environment.

Are we even ready to adapt to this? Climate change is undoubtedly one of the greatest challenges of our time. Less well known, however, is how much the construction sector contributes to global emissions. Often, public attention is focused on air travel, whose CO2 emissions are steadily rising. More and more people are therefore consciously choosing against flying, especially for domestic travel, and instead use the train, as this is the most environmentally friendly mode of transport. This topic actually has nothing directly to do with the construction sector.

We only use it to convey a sense of scale 55 00:02:58.620 –> 00:03:01.520 The total share of air travel in global emissions was in 2023 at around 2.5 percent. The construction sector, that is the way, how we build and use our buildings, was responsible for 37% of all emissions. That is an enormous amount. Just as we can reduce emissions in air travel through our behaviour we can influence, there are also options for action in the construction sector.

The first step is to become aware of how much our living- and working spaces contribute to emissions. Similar to flying, the figures here will also continue to rise. According to the International Energy Agency, the global building stock, both in the number of buildings and in area, will double by 2060. This is directly related to population growth. From around 8 billion today to about 10 billion people. Most of this growth is taking place in cities.

Better infrastructure and economic opportunities attract continue to draw people into urban areas, which are still particularly CO2-intensive. According to the United Nations, in 2018, about 55% of the global population lived in urban areas, a share that is expected to rise to 68% by 2050. The non-profit organisation Architecture 2030 describes the challenge as follows. the largest growth in the history of humanity to manage, is expected to be 240 billion m2 of new building space between 2020 and 2060 added to the global total.

That corresponds to the area of an entire city. like New York City, every month for 40 years. While in the countries of the global North a large part of the infrastructure has already been built, future growth will mainly occur in countries like China, India and the states of the global South, for example in Sub-Saharan Africa. We also know that there is currently no real scalable alternative to cement and concrete, and therefore no implementable solution for this major challenge. Nevertheless, construction projects, within development cooperation, can be seen as offering the opportunity to try out and demonstrate various low-tech solutions, that some of these different approaches are possible and can be regarded as equivalent or better than the usual way of doing things.

And what about support from local experts? Why do architects from Germany actually support such projects? For example in Ghana, aren’t there enough Ghanaian experts, who can do such things? Well, the short answer is, there aren’t. Especially when it comes to projects by NGOs, which have extremely low budgets and no means, to pay for various architectural services. There are far fewer universities and far fewer practising architects. So statistically speaking, many fewer people, who are interested in volunteer work. Let’s take a look at some statistics.

For the purposes of this video presentation, the following studies and surveys were used for most statistics. The figures have been rounded, some estimated, some may have changed by now, as most of these surveys were conducted more than five years ago. I think that’s of little significance. The statistics are quite self-explanatory, even if they vary slightly. This is the comparison between the so-called global North and the global South. In Germany, there are 63 times more architects and architects registered than in Nigeria.

In a country like Uganda with nearly 50 million inhabitants, there are according to available statistics 250 registered architects. Kenya has 2,000, with a similar population size to Italy, Italy has 160,000. Even if one assumes and knows, that there is a lower number of local experts, these figures are astonishingly low. Of course, the number of architecture schools and universities is proportional to the previous figures. These numbers would only be comparable if one knew, how many architecture students are actually admitted each year.

But to clarify the matter, these statistics are more than sufficient. There are many countries with a population of around 20 million, where there are only one to two architecture schools. And not only that. An even more important aspect is the question, how quickly certain countries are urbanising, where it is obvious, that this lack of experts will become even more pronounced in the coming years. The urbanisation rates in most countries of the Global South and those of the Global North are incomparable.

Uganda, with 250 registered architects and a population of 50 million people, has an urbanisation rate of 5.3%. It does not look like the increase in new graduates from higher education will keep pace with the urbanisation rate in the foreseeable future. The often-cited statistic states that about 70% of the buildings that will exist in Africa by 2040 have not yet been built. The real question is therefore not who will support the NGOs, but who will design everything else. The African Futures Institute, an organisation based in Accra, Ghana, conducts various events and workshops, organised a series of lectures from 2021 to 2023. They provide a small insight into this topic, the state of architectural education in Africa, the challenges and the ideas for the future.

When it comes to sustainability, the conversation often begins and unfortunately ends with the discussion about materials. Let’s analyse the situation a bit and look at the factors that could influence our decision-making process in using alternative materials. There are good reasons, why we use concrete and reinforced concrete for everything. It is an excellent material, that has been known for a long time. Already in Roman times, concrete was used for various structures.

And since the advancement of technology for the production of cement in the 18th century, concrete gradually became the most important building material. It is a mixture of cement, aggregates such as sand and gravel, and water. It can also be handled by unskilled workers easy to produce, is relatively easy to transport and can be used in combination with steel for almost any structural task. Moreover, it is very durable and is, although not completely waterproof, highly resistant to water.

Unfortunately, its production has an enormous CO2 footprint and offers no possibilities for circular economy. Once built, it remains almost forever. It is difficult to demolish and remove. According to various studies, the total emissions from cement production, including heating materials, are estimated to account for about 8% of global CO2 production. It is therefore understandable that alternatives are being sought everywhere. But it is also true that it is extremely difficult to compete with concrete.

First of all, it should be analysed which parts of the building can actually be replaced by the currently available alternative materials. When alternatives like bamboo and clay are mentioned, it always refers to the above-ground part of the building. These materials can only be used where they are well protected from water. This means that everything built underground, the foundations and the various load-bearing walls, are almost always made with cement. In this way, they are more resistant to water and capillary moisture.

The only other option, which is not based on cement, is the use of stones in areas where this is possible. The ground slabs are another part of the construction, where it is very difficult to replace concrete. On the ground floor, if the slab is not a load-bearing element, it is much easier to try other alternatives, for example, the use of clay floors. This is only doable in buildings that aren’t heavily used, and their design must account for –and have a budget for– regular varnishing and potentially renewal every ten years or so.

On the upper floors, the only alternative to concrete slabs is usually wood or bamboo. This is quite feasible, but if done properly, it is much more complicated to build than a conventional concrete floor slab. The average spans, the man can achieve with these alternative methods, are much lower, making it even more complicated for public buildings, to avoid concrete. This aspect is very important, to put the discussion in the right context. Often we focus solely on the visible tip of the iceberg.

An example from one of our completed projects, the ratio of above- to below-ground cement consumption was about 1 to 6. If we had theoretically replaced the beams and columns with alternative materials, it would have meant a reduction in total cement consumption of around 20%. That is undoubtedly a significant share, but not what many expect, when talking about sustainable building.

Knowing theory and built examples is one thing, implementing them practically in a new project, is something entirely different. Especially when working with methods, that are uncommon on site. Without local partners with experience in such building methods, the use of alternative materials hardly works. Local professionals must be involved throughout the construction process. Expertise can be imported, which can work for some design-build or prestige projects with high budgets, but is unrealistic in most cases. There are very few professionals for earth construction or bamboo, who could coordinate a construction project abroad.

And they also need support on site. At We-Building, we were able to use alternative building methods only thanks to dedicated, often hard-to-find local partners. Only through this was it possible to work with earth blocks or timber frame construction. Both are still relatively simple building methods. However, once it comes to rammed earth or bamboo, it becomes significantly more complex. Many projects start with great ambitions, especially in the choice of alternative materials, but then fail due to high costs, technical hurdles or lack of local support and end up with conventional building methods. So before deciding on a material, one should first find local experts and companies examine existing examples and align decisions with their knowledge, costs and availability.

Often it is the architects who want to use sustainable materials. But it is important to also convince the local people of the benefits. The often heard statement that only poor people build with earth, shows that many prejudices exist. What is meant are simple houses, which do not last long and are considered unattractive. It can look like this. But it should be said that it can also look like this. Or once plastered, it can also look like this.

If one wants to change that, the community must be involved, talk to each other and show real examples, what advantages such building methods have. Topics like carbon footprint or climate change are often too abstract. Better living conditions are more understandable, because the walls can store heat, insulate sound and breathe, or the positive effect on the local economy. In most countries, building regulations are rarely adapted to alternative building methods.

This means that in most cases, no building permit can be granted for projects made of rammed earth, plastic bottles, superadobe, bamboo or other unconventional building methods. can be issued. Many of the published examples, where alternative materials were used, come from smaller villages and areas, where perhaps no building permits are required. Or the drawings in the permits show different materials than those actually used in construction. There are probably many workarounds. It is a grey area.

That is also the reason, why sustainable projects are seen much more often in rural areas and much less frequently in larger cities. And for this very reason, this is the area, where most progress needs to be made, to implement alternative building methods on a larger scale. As long as the building regulations of individual countries is anchored, that such a construction method is legally possible, there will be no real large-scale changes, regardless of the many inspiring examples worldwide.

The maintenance of buildings is a central issue of sustainability. All buildings, whether made of concrete, clay or bamboo, must be regularly maintained. However, the budget for this is often tight, especially for public buildings. If there is no planning for ongoing maintenance, damages accumulate, until the repair eventually costs more than the regular maintenance itself. With clay and bamboo, the maintenance effort is usually somewhat higher, but that should not be a reason not to use them.

Regular maintenance simply has to be part of every financial plan including for donors and foundations. As for construction costs, in practice, construction methods with alternative materials are usually just as costly as conventional structures that heavily rely on cement. Hopefully, this situation will change soon, but currently it holds true, alternative does not mean cheaper.

Individual projects can have a significant impact, on communities as well as on professionals. It has been more than 20 years since Francis Kéré received various architectural awards for the school project in Gando, which was predominantly built with clay blocks. And even today, numerous young architects see this project as a model. At the same time, another very famous and often published example emerged, the METI School in Bangladesh. Built from clay and bamboo, a project that has made the bamboo construction method enormously popular among local professionals. Such examples show, that the impact goes far beyond the individual building. However, poorly implemented projects with alternative methods can have the opposite effect. Therefore, high-quality standards are crucial.

However, the sustainability debate should not only be about materials. There are many other factors, which are equally important or even more so. One area where there are still many opportunities for improvement regarding sustainability is W.A.S.H. In separate videos on this platform, one can see, through concrete examples, how sustainable solutions have been implemented. A central aspect is the improvement in the area of ecological sanitation systems. In general, it is about transforming the weaknesses of dry toilets into strengths.

Especially through the composting of faeces and the collection of urine for reuse in agriculture. This can not only represent a source of income, but is also a very sustainable approach, as resources are reused and principles of circular economy are implemented. Collecting urine is something that is often overlooked, even though it is by far the easiest to implement. Even in situations with running water, one can easily have separate urinals for boys and girls set up, where urine is collected and reused.

Another important point, which has a lot to do with sustainability, is the design and hygiene standards of toilet facilities, meaning how they look and how clean they are. These factors have a direct impact on how well they are maintained and how much attention is paid to maintenance. For only regular maintenance guarantees the longevity of such facilities, regardless of the materials used. If we are already expending resources and emitting CO2, then we should design the building in such a way that it has real added value.

Why not go beyond mere functionality? What can almost always be improved, are the micro-climatic conditions. And these do not necessarily depend on the materials. Cross-ventilation through large open windows, roof openings, to allow warm air to escape, or the avoidance of suspended ceilings, to increase the volume of the space. When we design public buildings, such as schools, libraries, kindergartens or similar, it should be a central goal to create better spaces. This is not a luxury and it is neither particularly complicated nor expensive.

With a little extra effort, one can create spaces, that inspire, that show, that a space can be more than just four walls and a roof. We all know from our own experience, it makes a big difference how the space looks, in which we spend our time.

Another significant aspect is the question of how buildings are used, with the aim of increasing their occupancy, so that they are hardly ever left empty. In some projects, this is already being implemented, for example, when a space serves as a church on weekends and as a school during the week. Not an ideal or particularly practical, but still a very sustainable example. This, of course, does not work everywhere, but often there are possibilities.

Classrooms could be used or rented out for community activities in the afternoons or evenings, large canteens could be open for events. This way, the utility of a building can almost be doubled. In the end, one should always ask oneself, do we even need to build new? Perhaps there are more pressing needs in the community, because the most sustainable approach is still to not build at all. If additional space is truly necessary, renovating existing buildings can be a very sensible solution, as can be seen in this example of renovating a library in Kenya.

The most well-known alternative building material is clay, as it can be found all over the world. One way to use it is to make clay bricks. The mixture depends on local conditions, but it is always a combination of sand and clay, usually in a ratio of 3 to 1. These are then filled into moulds and typically compressed in some way. If cement is added, usually about 4 to 7%, they are referred to as stabilised. This naturally makes them a less sustainable solution.

Here are some examples of air-dried clay bricks, as well as the more complex, compressed, stabilised clay blocks, which can be load-bearing and even reinforced with steel. As this is a fairly common building material, there are many other videos on this platform with numerous examples of what walls made from such blocks look like in practice. Another option would be the rammed earth technique, which has been used throughout history, as we saw in the examples at the beginning of this presentation.

A mixture of natural aggregates such as gravel, sand, silt, and clay is rammed into a formwork, to create solid walls. Here you can see a reconstruction, of how this technique was used hundreds of years ago in China. has been applied, with bamboo as reinforcement. The fundamental principle has since not changed significantly. Let’s go through the process now in a more modern variant, as it has been implemented in this specific project in Ghana. 526 00:25:21.060 –> 00:25:24.240 As is often the case, the foundations are the crucial part.

These walls can withstand rain, but are not resistant to prolonged water exposure or capillary moisture, so the earth part should always be slightly above the ground. In this case, a narrow foundation strip is excavated, some cement blocks are placed on it and finished with a small concrete ring beam. As with building with bamboo, there are also alternatives here, for example, foundations made of natural stone. But in all cases, it holds true that, for rammed earth walls, the lower part, that is, the foundation, is almost always constructed in a conventional manner.

This can also be clearly seen, when looking at the built walls. Shortly after, the mixing of the earth began. Depending on the location and conditions, different types of soil and mixing ratios are used. There must always be a certain clay content, and water is always added. As can be clearly seen in this section of the video, especially when zooming in on the cement bag, this case involves stabilised rammed earth, to which about 5% cement has been added.

This addition, similar to stabilised earth blocks, facilitates the construction process, so that even less experienced workers can carry out the execution. Moreover, this makes the walls more water-resistant. At the same time, however, the addition of cement significantly restricts the sustainable character of this building method and calls into question the entire idea of building with earth as a more sustainable alternative to conventional cement-based construction methods. Aside from the mixture itself, the construction method of the walls, whether stabilised or not, remains essentially the same.

The next step is the formwork. It is carried out in a similar way to that of a concrete wall. In this case, it is made on-site, by connecting plywood with the steel frames. However, there are many other options. You can use wood, metal, plywood or combinations thereof. Since the surface of the walls remains visible, the type of formwork also determines the final result. Here, they will have a smooth surface, because marine plywood was used.

The moist earth mixture is filled into the formwork frame and then compacted layer by layer. This can be done either manually or with pneumatic devices. In any case, it is a labour-intensive process. The compaction is done layer by layer, about every 10 cm, and the formwork is gradually added higher. Once the wall is completed, the formwork is removed. Finally, minor repair work is carried out and any holes are sealed.

Another example, which has kindly been made available to us for this video, comes from SINA, the Social Innovation Academy, a self-organised learning and community model in Uganda. SINA supports disadvantaged youth, including refugees, orphans, or former child soldiers, in starting their own social enterprises. Here is one of their many projects, which is interesting to us, as it relates to sustainable building. One of the solutions leads to Kampala. Plastic waste is scattered almost everywhere. In Uganda’s capital, over 350,000 tonnes of solid waste are generated each year.

But only half of that is disposed of. A large portion of the plastic ends up in this landfill. There is hardly any recycling. John-Mary Kawuma pays young waste collectors to fetch him bottles, which he can use for building houses. Every time I come here, I give them money for recycling and keeping the environment clean. This really gives me hope, that the future generation will inherit a healthy planet that we have protected from plastic waste.

The problem presented here led to the founding of Upcycle Africa, an award-winning social enterprise, that transforms plastic waste into affordable climate-resilient houses and sustainable products. One of the first buildings, constructed using this method, was built on the SINA premises. The rooms have a very distinctive appearance with a rough surface, characterised by the colourful bottle caps. Let’s briefly go through the construction process. The empty plastic bottles are filled with any type of soil that can be found in the area.

Ideally with the material, that is excavated during the foundation digging. It is important that the soil in the bottles is well compacted. It is a very labour-intensive process, but it has the advantage, that it can be carried out by anyone. Afterwards, the bottles are stacked on top of each other, to form walls. Cement mortar is used between the bottles, to bind them together. The main load-bearing structure consists of reinforced concrete columns. In this example, they appear quite massive, as they also use plastic bottles as formwork.

Concrete beams are then poured on top of these walls. A high level of precision is required, to keep the bottles in a straight line. For this, taut strings are used, which serve as a guide. What is clearly visible in this video is the high consumption of cement, for the mortar, the plaster, and the columns themselves. The special shape of the bottles was not intended as a building block and ultimately required a very high consumption of cement to connect the elements and all like in many other projects, this was also a compromise solution.

It brings important aspects with it, the use of waste as a potential resource, the strengthening of the local economy and the foundation for a social enterprise. The economic and social aspects of sustainability were therefore implemented very successfully. From an ecological perspective, however, the result still resembles conventional construction methods. The spaces created by these walls are very pleasant and provide significantly better microclimatic conditions than conventional cement block walls. Under the given conditions, this project was absolutely sensible.

But for many reasons, such as building regulations, fire safety and future advances in recycling, building with plastic bottles in this form is not a solution that can be scaled or can solve our environmental problems. The real message is different. This project impressively shows, that sustainable approaches always develop from the respective local conditions and that it is precisely in these project-specific differences that the greatest opportunity for more sustainability lies.