The city of Mombasa was built more than 800 years ago on the homonymous island located on the East Kenyan Coast. The island, thanks to its favourable position in the Indian Ocean, soon became the main port in East Africa. Its geographical location gave rise to a unique cultural identity, a mixture of Arabic, Persian, Portuguese and Indian influences. This cultural identity is particularly expressed by Swahili architecture, showing in its characterisation the artistic ferment typical of a port town, but also the constraints coming from environmental and climatic conditions. However, Mombasa city, in the last decades, has been filled with contemporary buildings distant from the traditional and sustainable coral stone architecture found in the historical centre in the South-Eastern part of the island.
The project by Urko Sanchez Architects goes in the opposite direction by reinterpreting the ancient tradition in a contemporary way. The rich Swahili architecture has given the designers not only a vast formal repertoire, but also a project methodology based on both a strong relationship with the surrounding landscape and bioclimatic passive climate control strategies. In fact, elements such as screened balconies, window shutters and courtyard spaces were used in the ancient town to facilitate thermal regulation and cross ventilation.
Starting from the know-how of the Swahili vernacular architecture approach for designing passive buildings in the local warm-humid climate, Urko Sanchez makes passive ventilation one of the central themes of the project: the NE – SW direction of the longitudinal axe of the building facilitates the circulation of prevalent winds, which blow from November to March from north-east and from April to October from south-west.
The Tudor Apartments, located on the creek waterfront in the North part of Mombasa, are surrounded by dense vegetation. With the precise aim of maintaining a constant dialogue with nature, the architects have decided to leave the mangroves and other trees intact on site even to preserve their contribution in protecting the coast line: the mangroves root systems trap sediments flowing down rivers, preventing sea waves and storm erosion.
For the same purpose, the building adapts itself to the territory morphology following the sloping of the land through three distinct patio houses, overlaid on each other and opened in the creek direction. The patio houses are accessible via lateral stairs which connect the principal entrance of the building and the creek, passing by the gym at the bottom and arriving to an infinity pool.
On the hilltop, directly collocated to the patio houses, there is the main building, placed at a measured distance from neighbours and roads, to guarantee a sufficient level of privacy to its inhabitants. Constituted by ten apartments with terrace and a penthouse, the apartment block is enveloped on three sides by a Moucharabieh structural shell which has the double aim of filtering solar radiation – besides letting in the natural bright light – and to consent natural passive ventilation. The Moucharabieh systems, widely spread all over East Africa, utilise intricate geometries to reduce the wind exposed surfaces increasing air passage. Their effect is even more amplified in proximity of basins of water which allow the diffusion of fresh air inside the houses.
Besides the white plaster finishing of the Moucharabieh shell, whose colour permits the reflection of excessive heat, the project uses mtomo finish, a Lamu typical cladding technique which employs the local coral stone, available along the coast. Furthermore, the coral stone has low embodied energy, which means that it retains less heat and cools down faster than other similar materials, like concrete blocks.
In most cases the shell construction directly limits the internal spaces, while it is only the first element of sunlight and heat screening in the façade facing the street. Here the external shell is complemented by an internal handcrafted wood lattice shutter which outlines a buffer space. While the South front of the building is surrounded by the shell, the Northern façade is completely free to allow harmonious interaction with the sea. The balconies are conceived as a filter between nature and entropized space guaranteeing air movement and heat dissipation, through the cross ventilation obtained with the shell openings. Large overhanging balconies also provide an efficient sun screen system, playing a significant role in mitigating high intensity solar radiation.
In the patio houses the ventilation scheme is even more complex: the wood lattices placed on the terrace floor and in front of the false ceiling allow air circulation from the seaside to the interiors. Particularly the ceiling openings facilitate air movement under the covering slabs, avoiding the transmission of heat from the sun to the top terraces. The patios themselves ensure an additional ventilation system, due to the high walls encircling them which are able to “collect” wind and to create convection currents. Moreover, vegetation is integrated on the patios and the terraces, offering freshness and greenery and creating a pleasant atmosphere on hot days. All the wood works mentioned and the coral stone cladding elements, have been constructed by local craftsmen.
In addition to the above environmental strategies, due to the absence of a proper connection to the sewage system, the architects also integrated a bio digester for treating used waters and installed rainwater collectors in order to provide water for the gardens.
To conclude, the award-winning design (AAK-Awards of Excellence in Architecture: Best Residential Project, 2013-Honorable Mention) by Urko Sanchez Architects found in the ancient Swahili houses a reference for designing contemporary architecture. The vernacular typology that can be considered a result of the interplay of cultural and physical factors, with a strong environmental response to the local context and climate, is read and reinterpreted to rediscover an “old way” to deal with new climate responsive design solutions.
Architecture relationship with landscape, the wide use of social meeting places, such as terraces and patios, the attention given to spatial quality research and environmental aspects, the utilisation of local material and craftsmanship, are all elements which demonstrate how a sustainable design culture is possible starting from the acknowledgment of tradition, with the goal of reconstructing links between nature and human beings.