Cases that matter

Open Source House

Worldwide, more than a billion people live in slums. Most of the inhabitants of these slums are surprisingly, people with stable jobs and income. High mortgage rates and a lack of affordable houses are barriers to homeownership for the rising middle class in developing countries. These barriers force people to build their own houses and reside in slums.

On a trip to Tanzania, Dutch architect Vincent van der Meulen discovered the great demand for affordable housing among the growing middle class. Being excluded from the housing market, these people were forced to build houses themselves, often in an unsustainable way. From his experience as an architect, Vincent knew more sustainable and affordable ways to build houses.


After he returned to the Netherlands, Vincent approached Enviu to collaborate on this issue. Around the central question “how can we unleash the international knowledge about sustainable building for people in the emerging middle class”, Enviu and Vincent developed the Open Source House concept.

As an experienced partner in initiating mass collaboration and co-creation, Enviu was able to soon bring this project to a higher level. The development Sustainable Dance Club gained worldwide recognition through its innovative approach in co-creating impact solutions by engaging with big groups of people.

Seven months, four sponsors

During the seven months of preparation, the project team decided on a focus country and city (Cape Coast, Ghana), established local relationships, and conducted research about social characteristics and stakeholders in Ghana. Enviu achieved to get a grant from the Dutch VROM Ministry and signed sponsorship agreements with COM.wonen, Dura Vermeer and NCDO to finance the challenge.

Five months, over 3.000 architects, almost 250 building plans

In 2007 Enviu launched the Open Source House challenge. Architects from all over the world were given the assignment to design a single family house for the emerging middle class in Ghana on a plot within Cape Coast, Ghana. Within five months 3100 architects from 45 different countries submitted 247 designs for a sustainable house.


A small selection of designs were presented during the final event in Amsterdam which attracted some 500 spectators. Finally, the ‘Emerging Ghana’ entry won the open source competition. The winners of the challenge won a pressure cooker event together with Vincent van der Meulen, where the design was adjusted and improved.


Fail and learn

Enviu started building the house in Ghana as a pilot and soon found out that the costs for building the house in Ghana, were higher than initially calculated in the plans. Due to the fact that technology used in the plans, was not yet common in Ghana the plans turned out to be more expensive than planned.

Besides the costs to build the house, more issues arose. In Ghana the typical mortgage rates were 30% per year. This turns the total costs for financing a house for an end-user into an insurmountable barrier, at least if the mortgage works as it currently does.

As well we learned that the design didn’t correspond with the local cultural preferences. For instance, the house was too open and didn’t enough give the feeling of security. The setup of the house was neither in line with how Ghanaian people like to live. The kitchen was closed and had a roof; something they didn’t like because all the food smells would be trapped in the house.

If you don’t have buyers, you don’t have a business

After the Open Source House, Enviu faced the value of the Lean Startup Methodology: if you don’t have buyers, you don’t have a business. Though the Open Source House project caused an amazing movement, the end product never came on the market due to high costs and low demand.


Early 2012 Enviu and Dutch entrepreneur Rick Holt started INURBA to fulfil the promise that Open Source House offered. INURBA will deliver affordable and sustainable housing in the form of complete communities to the emerging middle class. The houses are provided with infrastructure that includes clean water, sanitation facilities, and power.

Currently there’s an agreement on building 240 new homes in Nigeria. Different from the original designs but, built with the same vision: building sustainable, affordable and comfortable housing for the upcoming middle class in emerging countries.

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