The brief for OTTO was to create a sustainable house, that would later serve as tourist accommodation, that would be climatically comfortable and have an element of rammed earth. It was to utilise the view to the North of the Boro and Thamalakane river. Maun is situated along the Thamalakane fault that forms the South end of the Okavango Delta and is a frontier town servicing the tourist industry to the Okavango Delta. The Landscape is exceptionally flat so a site with a view is unusual.
Simply Sustainable was responsible for the design of the building, but also took on the additional tasks of project managing the construction, as well as doing the interiors, This gave control on all aspects of the project team and we were able to ensure that sustainability became the guiding principle of the design.
The house has been simply planned with a single bedroomsand an open plan living area. Thick rammed earth walls create cave like spaces and care was taken to create shaded outdoor areas and ensure cross and stack ventilation. The thick walls are well shaded to ensure that they work as heat sinks and remove the energy from the room keeping the spaces cool. A natural pool around three sides of the house with a low window further assists by creating evaporative cooling, while the water around the house creates a calming environment.
On site material was used extensively and the site was landscaped to increase its flood resilience (as climate change makes predicting the future very difficult), with the house raised high up on the bank . The use of local material, reduced the transport CO2 footprint, and local labour was extensively trained to do the construction.
The house was designed to be off grid with rooves optimised for solar pv & solar heated water. They were also insulated with three layers of insulation to ensure no heat gain, as temperatures are often over 40 degrees Celsius
Made from the site soil it will return to the earth when it reaches the end of it’s life having a small ecological footprint . It is low carbon during construction, during it’s lifespan and at it’s end. Made from site material, the colours harmonise with those of the soil, and the house is the landscape. The stabilised rammed earth is a mixture of site soil(72%) crusher dust (25%) and hydrated building lime (3%) and is durable (and tests show this) and it’s construction minimised impact. Chemically treated sustainably grown softwood timber was used to make it termite resistant
Passive thermal elements reduce it’s energy demand. Thick shaded rammed earth walls use their thermal mass to keep the indoor temperature constant, drawing out excess heat energy. Windows are placed to catch the incoming breeze, (mainly N to NE) and cross and stack ventilation brings cooler air in and exhausts hot air. Low energy ceiling fans assist this airflow on still hot days. The triple insulated roof prevents solar heat gain. A swimming pool is close to the house, cooling the air. The design is in harmony with the environment, in material and in function.
It is extremely challenging in the southern African context to address the large inequalities in the building sphere but a serious attempt on this project was attempted. All construction workers were treated with dignity and employed under employment contracts. Most of those employed had not worked on a construction site before. Local labour was used throughout and an emphasis was on training and skills transfer. The site carpenters employed to build the formwork and fix the roof, were up skilled into cabinet makers and made the furniture. All those who did the ramming had not worked in construction before, and learnt setting up, building to level and trained to read plans.
No trees were cut on the site and it was cleverly positioned to take place in harmony with the environment. The front bank was extended to create privacy and a level piece of outside area.
Factory manufactured materials were reduced, the doors (including the ironmongery) and windows were made on site, creating local employment and reducing transport. Hardwoods were FSC certified, or sourced locally with the source being verified by the project team. Cabinetry, and furniture was also site manufactured and little construction waste was generated.
The building process used predominantly natural on site material and where possible materials were obtained with the least carbon miles. The buildings are not considered as objects in a foreign environment but as part of a single environment. Design is not an idea handed over for others to produce but a vision on which we create the environments from what is there, to what we need, with the people that are here, and have the ability to learn to produce quality and durable objects.
The house reinterprets the local vernacular both in material choices and its aesthetics. Traditional Maun homesteads were a number of houses built by placing stakes into the ground end on, with a thatched roof. The gaps between the poles allowed for cross ventilation and took advantage of the cool desert skies. This aesthetic is reflected in the letake (reed) screen to the north verandah as well as in the shack reflecting both aesthetic and function and the functionality in the high windows that allow hot air to escape at night. It achieves a sense of place with the juxtaposition of its cool shaded spaces and its openness to the surrounding environment. It connects to a tradition of lives lived with connection to water, to migrant lives and to lives lived outdoors.
Simply Sustainable has been engaged in sustainable Architecture in over 15 years, and has grappled deeply with the issues in how we can develop in a way that uses only renewable and low carbon resources. It publicised rammed earth technology and one can see a large increase in projects that now reflect it. It has designed a series of buildings that optimise passive techniques. This project has resulted in others building with low footprints. By promoting sustainability throughout and exposing greenwashing this has had positive impacts on clients . I believe that a consistent message is having an impact and Otto cottage designed by simply sustainable became one of the 15 most desirable location of Airbnb globally. We impacted over 100 people in this project, and I believe that a high visibility project such as this will impact 1000’s over time. We engaged with suppliers to find out on the impacts of what they supply.
A sustainable Architecture and Construction practise specialising in ecological design , natural building and rammed earth