Ethiopia and especially Addis Ababa are places of great change. Rapid urbanisation makes Addis Ababa one of the fastest growing cities on the planet, tenfolding its population since 1950. But at the same time building materials are scarce, almost everything from concrete to steel has to be imported. Ethiopia’s forests have been cut down by around 70% in the last century and people are desperately trying to save the remains.
All these factors make construction by standard western means – e.g. reinforced concrete structures with chemical insulation - unsuitable, expensive and ecologically problematic. But still, almost all of the current building projects in Addis Ababa are build in that way.
The potential architectural answer to these problems is deeply rooted in Ethiopian culture and far from innovative: earth. Rammed earth construction is essential to Ethiopia's rural architecture, but therefore known as a material for the poor. It is seen as a material of lesser worth and its bad reputation might be the reason for its decline in Addis Abebas urban architecture.
But local experts like Helawi Sewnet and Zegeye Cherenet are campaigning for a new, sustainable and affordable building practice in Ethiopia, centered around earth as its main material. Numerous projects and publications by people like Martin Rauch and ZRS Architekten proove, that rammed earth can be used extensively for the demands and applications of a modern building. Its outstanding climatic qualities and its capability to bear loads allow for monolithic construction which is not only elegant but also quick to build and cost effective.
Our design for the Czech Embassy in Addis Ababa tries to resurrect the traditional Ethiopian material earth, by celebrating it in a building of highest representation and by combining it with the clear and careful shapes of Czech modernism.
The typology of an embassy is particularly unique. Inherently different and sometimes conflicting functions have to be combined into one structure. This structure does not only serve representative functions but also has to provide a comfort for visitors, employees and especially inhabitants, all while retaining a high standard of security and complexity. The biggest conflict, which is unusual even for an embassy, is the fact that the czech employees will live and work on the site. They will expect a difference in typology between the place they work and represent the czech republic and the place they live with their families. This contrast will have to exist architecturally, but the structure as a whole has to remain as one, both visually and functionally.
The central aspect of our design is the use of the wall. As an element which has remained particularly important to czech modernism, it is not just used to surround a room, but rather to create spaces, direct views and embrace direction. It takes on three shapes in our design which are all used throughout the complex and each serve some of these functions: spatial separation, visual separation, climatic separation and load bearing.
The most important element is the rammed earth wall. It is the only load bearing vertical structure of the design and is used for the spatial separation of the individual structures. Firstly it separates the whole complex from its surroundings by forming a 2.7 m high wall around the plot. Secondly, it forms the main structure of all the buildings of the complex, carrying the roof and dividing different interior sections. The concept of free standing walls, which was essential to czech modernism, is applied in our design and allows for free flowing floor plans with open spaces. Third, and maybe most importantly, the earth wall also divides the exterior spaces. As rammed earth is itself a good insulator, an interior earth wall can be extended into the exterior spaces to provide separation between different security zones or uses, like the representative garden and the gardens of the residents. Free standing exterior walls can also shape spaces to provide privacy in an otherwise unprivate environment.
The second element is the glass facade. The climate of Addis Ababa is one of the most forgiving climates in the world, allowing for construction practices which would not be possible somewhere else. One of these practices is to freely connect the interior with the exterior, by providing large glass facades which can be widely opened to extend spaces like the representative hall or a personal living room with the outside. This interconnection makes an otherwise crowded plot seem more open and roomly.
The third element is a corten steel panel which provides privacy and visual separation while still letting in light. It becomes particularly important in combination with the glass facade, as it can partly seperate rooms like a bedroom or a secure office from visual contact with the outside, while retaining the feeling of an open space. The panel is decorated by a laser cut pattern. This pattern is inspired by the diamond glass polish of traditional bohemian glass manufacturing and is transferred to a material which correlates in its natural appearance to the earth walls.
These three wall elements are then covered by a concrete slab, which lies freely on the walls, forming both interior and exterior spaces underneath. Its overhang provides shelter from the sun and the large amounts of rain, which Ethiopia experiences in the summer.
The plot is divided into two main parts, the official part to the west and the residential part to the east. As most guest will arrive from the west, the main facade is oriented to the new street created in the western part of the plot. The outer wall is replaced by a fence and creates a large space in front of the official building, which allows pedestrians and visitors to fully see the representative facade of the embassy. On the opposite side of the street, outside of the security perimeter, the building for the local workforce continues the architectural language, framing the space in front of the embassy.
As you enter the representative part of the embassy via the entrance hall, you will be presented with a transparent architectural structure and a view of the representative garden. If the weather is right, the large glass facade will be completely folded open to seamlessly connect the lounges, dining room and representative hall with the garden. Similarly, visitors to the residence of the ambassador will approach the garden from the north, gaining extra privacy by the exterior walls but the same amount of openness which interconnects all representative spaces.
To the south, the offices shield the representative garden from the outside. Their entrance creates a symmetry to the representative entrance, embracing the axis of entrance as a whole. More security sensitive offices are directed towards the plot and are additionally shielded by the corten panels. The basement of the office building contains all the technical support, concentrating all security critical areas on one building.
On the southern border, the consulate is the only building approaching the street directly. It adds an additional security barrier towards the office, all while representing the embassy and its architecture to the regular visitors and applicants.
The eastern, residential part of the complex is separated from the representative part by a height drop of 1.9 m, which provides an additional visual separation to the outer rammed earth walls. Activities in the representative garden are adequately shielded from the residential areas and vice versa. The only two buildings connecting both parts are the office building and the residence.
The office building doesn't allow views from the apartments into the offices, but it opens spaces like workshops and rooms for the gardener towards the residential parts. Also the basement can be accessed from there.
The residence has its apartment areas in the residential part of the plot and the representative areas in the representative part of the plot. It allows the ambassador and his family to freely move between them without connecting the two areas for visitors. The residence has an additional garden to the north, which can be used for private purposes or unofficial visits for the ambassador.
The apartments for the czech employees are noticeable smaller structures, appearing as a small village in a tessellated garden. It was imperative to create private spaces for each family not just inside, but also outside. The separation of the building volumes into smaller units creates the feeling of living in a structure that is different from the place of work, a structure that is free for the residents to make their own. Every apartment has a second floor including a terrace, allowing for views over the cities and an escape of the surrounding security wall. On the ground floor, exterior spaces flow together and create shared spaces, like the ones containing the pool and the tennis court.
Rammed earth is not only economical, but also climatically ideal for the location. It is a fairly good insulator, a very good moisture regulator and most importantly a excellent thermal mass. By joining these factors we aimed and succeeded to created a building which can function completely passively. The large concrete roof overhangs collect solar heat during the day and give off heat during the night. This heat is transferred into the the interior via the intentional heat bridge and in combination with the large thermal mass of the walls and ceilings provides a very stable interior temperature.
We have performed climate simulations taking into account the local climate and the thermal loads by employees and equipment. Without active heating or cooling we have been able to keep the temperature between 19°C at its lowes and 24 °C at its highest throughout the year. These temperatures allow for a completely passive building, which sources all its additional energy demands from solar energy and therefor is completely independent of the network, increasing its security.