The Nubian Vault - Low-Carbon Affordable Housing Solution

The Nubian Vault Association (AVN) is working to solve the massive challenge of providing affordable quality housing in Sahelian Africa, adapted to climate change and socio-economic realities.  

Millions of Sahelian families lack access to decent housing. The population of the Sahelo-Soudanian area is estimated to grow from 250 million inhabitants in 2013 to 650 million in 2050 (based on the World Population Prospects, United Nations, 2013). Today, the majority of the Sahelian population is living in precarious unhealthy tin-roof shacks while being at the forefront of climate change.  

Even though housing represents a primary and permanent concern for many communities, and population growth is fueling the considerable demand, this major problem is widely underestimated, and addressed rarely or not at all by public bodies. To date, there is no widespread international institutional program with a serious remit to provide access to decent housing for all in Sahelian Africa.  

1/ Deforestation and inappropriate expensive imported materials

Deforestation and desertification in the Sahel have led to the disappearance of bush timber and straw used in traditional architecture. Despite their apparent appeal, ‘modern’ technical alternatives and the materials which they require (cement, steel, corrugated iron roofing, girders, etc.) as well as the monetary systems which their use entails (imports, use of cash) have failed to deliver appropriate and sustainable housing to the majority, plunging millions of families into a vicious circle of poverty and discomfort, further increasing their vulnerability.  

2/ Demography, poverty, lack of jobs and revenues

The population growth is estimated to increase by 150% in the Sahel region before 2050. The needs for homes, for local jobs and a viable local economy will follow the same trend. Poor living conditions inevitably accelerate the abandonment of subsistence farming and the flight of rural communities to overpopulated urban centres. According to the World Bank, about 48% of the youth in West Africa between 15-24 years do not have jobs. With a fast-growing demography fueled by the 38% of the population aged between 0 - 14 (Statista Research Department), actions are urgently needed to bring new perspectives and credible alternatives to migration or illegal activities.  

3/ Climate change, the escalation of a major problem

African communities are particularly vulnerable to current and predicted trends in climate change (increase of mean and extreme temperatures, changes in rainfall patterns and wind speeds, droughts, desertification), making even more urgent the need for sustainable, comfortable, affordable housing. Even though the Sahelian populations have played a negligeable role in contributing to climate change, the fragility of their ecosystems and their lack of savings gives them very limited resilience or the ability to adapt to the changing situation.

The Sahel region is one of the most vulnerable to the effects of climate change, not only because of its biophysical characteristics, but also because of environmental degradation, poverty, food insecurity, rapid population growth, political instability, and conflict. Climate change is likely to exacerbate these existing vulnerabilities.

According to the ND-GAIN index, which reflects a country's vulnerability to climate change and other important challenges in combination with its readiness to improve resilience, all Sahel countries rank among the 20% most vulnerable and least prepared for climate change. Mali and Burkina Faso are even among the 10% most at risk.

The ICPP report predicts a temperature rise of + 2 degrees in the Sahel in the next decade. The housing conditions of most of the population will further deteriorate, as they are living under tin roofs which provide zero insulation against extremes of temperature and noise, affecting their quality of life and their health.

The multiplication of more extreme weather events will lead to an increase in the phenomenon of widespread  damage to buildings with flimsy tin roofs - although no study focuses on this phenomenon, it is readily observable on the ground. Repair costs weigh heavily on already fragile households.

In the Sahel, two out of three inhabitants live from subsistence agriculture and animal husbandry. The Intergovernmental Panel on Climate Change (IPCC) predicts that agricultural yields will decline by 20% per decade by the end of the 21st century in some areas of the Sahel. But already, the crises are chronic. Between June and August 2019, during the difficult lean period between the dry season and the rainy season, around 9.7 million people were suffering severe food insecurity in West Africa, according to the FAO. Complementary off-season job opportunities are vital.  

The issues of health and life expectancy are implicitly linked to housing conditions. Housing conditions in Africa are at the heart of the new economic, environmental, and climatic challenges and, of course, at the heart of our human wellbeing! Tin or zinc roofing for all is not a solution and the emergence of a resilient and sustainable eco-construction sector is one of the cornerstones of a trouble-free future.

Since 2000, the goal of the Nubian Vault Association (AVN) has been to develop a market for sustainable housing in West Africa, providing vulnerable populations access to affordable housing that is comfortable and well-adapted to climate change, and at the same time creating green jobs and strengthening economies at all levels.  

At the center of this program lies an architectural concept that is both ancestral and innovative, based on local materials, economies and knowledge: the Nubian Vault technique. The large-scale dissemination of the Nubian Vault technique over the entire Sahelo-Soudanian strip would provide millions of people with access to sustainable and comfortable housing adapted to climate change.  

1/ The Nubian Vault technique – the core concept at the heart of our program

The Nubian Vault (NV) is an age-old architectural technique of vaulted roofs constructed with mud (adobe) bricks and without formwork, originating in Upper Egypt and historically unknown in other African regions. Its specificity is marked by:

• the use of widely available raw earth to make mortar and sun-dried bricks,
• the fact that a timber framework is not necessary for construction of the vault.

The inertia of the Nubian Vault structure (created by the substantial thickness of the raw earth walls) entails a significant alleviation of temperature changes inside the building.

AVN has simplified and standardized this technique so it can be readily taught to rural populations with little or no schooling.  The technique requires simple skills and locally available materials (rocks, earth and water) and employs a significant amount of local labor.    

 Compared to current alternatives, a Nubian Vault (NV) building is:

• More durable: a NV house has thick walls, is resistant to rain, and can be passed on from generation to generation;
• More comfortable: it provides thermal, acoustic, aesthetic and usage comfort, and offers an option of traditional terraced roofs and an upper storey;
• More ecological: no wood or straw, no production or transport of imported materials (corrugated tin roofing sheets, cement, steel rafters), and thermal stability limiting the need for air-conditioning
• More economical: up to 50% less expensive than other building techniques for the basic structure;
• More adapted to the local economy: only local labor and materials are used, clients are directly involved in the building, costs are re-injected into local circuits;
• Easy to reproduce: simplified and standardized, the technique can be readily learned, with no particular educational requirements and only basic tools. lts simplicity and standardization also guarantee stability and durability.

Read more about the key points on appropriate housing  

The Nubian Vault is a technique that is appropriate for private and community use in both rural and urban environments:

• The NV for private housing -> watch the video

Rural Nubian Vault house in Selavip Boukargou (Burkina Faso)

Rural Nubian Vault house in Ziniare (Burkina Faso)

Urban Nubian Vault house

• The NV for community use -> watch the video

School in Po (Burkina Faso)

Health center in Nguendar (Sénégal)

Onions storage building in Fao Yako (Burkina Faso)

2/ A market-based approach to ensure the development of a resilient eco-construction market

The Nubian Vault Association (AVN) has always applied a market-oriented approach, thus ensuring the relevance of its solution and creating the endogenous and sustainable engine behind the dissemination of the NV concept. Therefore AVN’s objective is not to build nor donate houses but to contribute to the emergence and growth of a self-sustained NV eco-construction housing market, enabling its local appropriation. Our mission will be accomplished the day we can withdraw from a locality because the market will be strong enough to pursue its development by itself, providing decent housing to the many, and jobs and revenues for the community.  

To create and evolve this market, our methodology is based on three complementary levers:

- Support the offer with the implementation, strengthening and diversification of technical and entrepreneurial training for jobs in the NV construction sector (apprentices, masons and artisans), in order to ensure an autonomous green professional sector;

- Support the demand with sensitization to the NV architectural concept, and support to kick­starting local NV markets, both public and private, rural and urban. Financial incentive tools, an essential lever for rapid market growth, are proposed to the rural core target clientele, while at the same time microfinance operators are encouraged to join together to sustainably develop new adapted housing loan products.

- Support the business ecosystem with the mobilization of all stakeholders in disseminating the NV market and ensuring its perpetuation (operational partners, relay partners including political actors, technical partners, financial partners), and advocacy activities on behalf of the market and the right to adapted housing led by local leaders trained by AVN to foster a supportive institutional context for the NV solution.  

3/ An operational and replicable methodology enabling a large territorial dissemination

In order to promote a large-scale deployment, a key point of our strategy is the transfer of our methodology to Operational Partners (OP), locally embedded community partners (farmers’ or artisans’ organizations, womens’ groups, etc.) incorporating responses to the housing challenge into their missions, thus guaranteeing strong and growing impacts.

Accordingly, AVN operates at three levels:

• The mobilization, training, and accompaniment of Operational Partners who adopt AVN’s methodology, thus duplicating the development of the Nubian Vault market in their zones of action
• The organization of support functions essential to the implementation of this strategy: training, technical support, follow-up and evaluation, feedback, facilitation of a network of partners, advocacy, etc.
• The continuing promotion and diffusion of the Nubian Vault concept as an operator in specific territories, so as to consolidate the deployment procedures and explore new technical and methodological approaches.

AVN mobilizes partners at two specific territorial levels: Implementation Units (IU), and Implementation Territories (IT) as explained below, ensuring a coordination at multiple levels, international, national and regional.

Read more about the Diffusion of the Nubian Vault in the Sahel: Strategy, methodology and partner roles

This transfer allows for the proliferation of NV market clusters and the associated benefits; the goal is to eventually ensure the autonomy of the implementation zones led by these Operational Partners and hence the viral dissemination of NVs.

The dissemination of our UI/TI methodology constitutes the core of AVN's strategic evolution and the main lever to scaling up the spread of the NV market.

In other words, if it is better to teach people how to build a house rather than give them houses, it is even better to transfer to national and local actors the necessary skills for the creation of a dynamic and evolving endogenous market.

Since the launch of the program in 2000, the market for Nubian Vault buildings has demonstrated its capacity for growth:

• 2000: 10 NV houses a year
• 2010: 100 NV houses a year
• 2020: 1,000 NV houses a year
• 2030’s objective: to build 10,000 NV houses a year

See more figures and results in the dedicated section below.

The entire program implemented by AVN primarily targets the most fragile populations within five West African countries, themselves among the poorest countries in the world. AVN is deploying its methodology for disseminating the Nubian (NV) market in the rural areas of its countries of intervention. Our priority target beneficiaries meet the following definition: people in rural areas, living mainly from subsistence agriculture, working mainly in an informal economy. Moreover, no educational level is required to access the training program to become a mason or an apprentice, which makes this dual (on-site and off-site) training in the villages particularly inclusive.  

NB: With the growth of terrorist-related Internally Displaced Persons observed in Burkina Faso and Mali, AVN is currently setting up specific projects with new partners (UNHCR, DRC, WHH), targeting this specific segment of the population.

Offering a decent housing solution to Sahelian rural families (clients): the NV solution offers a greatly improved comfort thanks to its natural thermal and acoustic performance. Client participation in construction efforts (supply of materials and unskilled labor) helps reduce construction costs. In these cases, NV construction is 20 to 40% less expensive compared to conventional solutions of corrugated metal roofs and cement walls. See the major benefits of the NV technique in the section above.  

Providing professional training and jobs to rural youth: the project mainly targets young people between 15 and 35 years old, representing nearly 35% of the rural population. It provides the professional integration and entrepreneurial training of nearly 1% of them, taking into account their specific needs linked to a very low rate of schooling. Thus, the transmission of know-how through improved informal learning is perfectly suited to this largely illiterate population, making the training program particularly inclusive. As an off-season job, NV apprentices and masons can earn money during the long period of agricultural inactivity (between 6 and 7 months!) providing additional cash income. As NV construction does not require costly tools, the industry is therefore not dependent on heavy initial financing which could penalize the start of an activity.  

Providing capacity building to community-based organizations - CBOs (operational partners): these players benefit from training, support and capacity building from AVN during the territorial deployment of the dissemination methodology of the NV market.   

In summary, providing widespread decent, affordable, and low-carbon housing allows for:

• Better living conditions for Sahelian families with a significant increase of their quality of life; NVs provide passive natural insulation that helps to overcome heat peaks inside homes (5 to 7 degrees gained compared to a house with a tin roof). Faced with the rise in temperatures caused by climate change, this gain in comfort is essential for the comfort and health of these populations.
• Reinforcement of local economies, providing professional training, off-season jobs and revenues. NV construction requires the mobilization of a strong local workforce. Thus, the money traditionally invested in the import of expensive and high carbon footprint materials is redirected instead to pay for this labor and helps fuel a local economy.
• Decrease in pressure on timber resources: already vulnerable ecosystems will be further weakened by the effects of climate change. NV construction does not require the use of timber and straw.
• The re-appropriation of an “archiculture” and traditional know-how.
• A significant reduction in carbon emissions associated with this low-carbon construction technique and the Nubian Vault’s passive thermal performance, reducing energy consumption for air-conditioning and ventilation.
• Population stabilization: with better living conditions (adapted housing, professional training and jobs, local economic development) rural populations will be less likely to leave to find work in the towns and cities.  

The AVN Program, with its frugal technology and social entrepreneurship approach, not only offers a durable answer to the housing problem, but also contributes to the resilience of Sahelo-Soudanian populations, economic autonomy, youth employment, professional training, and climate adaptation / mitigation.

The Nubian Vault Association (AVN) was established in 2000 by a French mason, Thomas Granier, and a Burkinabe farmer, Séri Youlou. They both met in Burkina Faso, during the PIAMET (a local exhibition of traditional arts) where they first tried to build a Nubian Vault. Therefore the story of our program started in the field and was co-designed by a Burkinabe farmer, who did not know how to read nor write, and was himself facing the various challenges of the region.  

Since then, the program has kept this bottom-up culture, and its proximity with the communities we are serving. Most of AVN’s teams in Burkina Faso, Mali, Benin, Ghana and Senegal (49 staff in 16 regional and national offices) are locals from rural communities.  The program managers and trainer masons are from these same communities the project intends to serve. On the other side, the team in France - in charge of operations, fundraising and relations with international donors, communication, reporting, impact evaluation, internal auditing, finances, etc. - is mainly composed of master’s degree graduates. There is a strong cohesion within our local teams between AVN’s collaborators, operational partners and trainer masons, but also with our team based in France who regularly spend time in the field.

This complementarity of skills, expertise and experience enables our teams to operate and work closely both with a Sahelian population among the poorest in the world, and with the management teams of international organizations among the most influential in the development sector, as well as with Ministries of European and African States.  

AVN has more than 20 years experience in the field. Our strength is our network of 52 local offices and operational partners in the field (4 national offices, 12 regional offices, 10 PO-TI and 26 PO-UI - See the schemes above, in the section "What is your solution" explaining the roles of our PO-TI and PO-UI) allowing us to intervene as closely as possible to the targeted rural populations. As mentioned above, over the years, AVN has developed an operational and replicable territorial diffusion methodology that requires very little expertise so it can be transferred to locally embedded community partners (farmers’ or artisans’ organisations, womens’ groups, etc.). Through their legitimacy and their networks, these partners effectively deploy the program in their own territories for the long term. Even in those zones, such as northern Mali,  which are currently experiencing issues of growing insecurity our teams can still keep operating. Since the begining of the program, 5200 NV buildings have been completed, disseminated in 1500 localities in 6 countries.

The design of the program is continuously being improved, based on the feedback from our teams in the field and from our operational partners (local community-based organizations), the masons and apprentices we train, and of course the beneficiaries using or living in Nubian Vault buildings.

After more than 20 years the program has proved its worth and is now poised to significantly scale up its operation. The good news is we think we cracked the code to enable our program to scale-up. Indeed, we have defined the principles of a business model that should lead our program to reach self-funding within five years while ensuring a 10% growth a year for the years ahead. In a few words: we will sell carbon credits - generated thanks to the carbon reduction of our low carbon constructions - whose revenues will allow AVN to offer financial incentives to Sahelian families to help them funding their Nubian Vault houses (as the financing is now the major barrier for them to engage in such an eco-construction project). The more of these low carbon houses are built, the more carbon credits are generated, the more revenues are available to fund more houses, etc.  We explain the details of the business model below in Your Business Model and Funding section.

However, to make this change of scale possible and to transform this idea into impactful results, we would need support in the following areas:

• To share, test and improve our strategy for scaling up with the Solvers community. We could need support and expertise on the voluntary carbon market (to explore opportunities to set up a specific financial organization dedicated to funding the program through trading of carbon credits, to create a carbon label adapted to construction projects and/or enhancing the co-benefits of adaptation, to run a joint advocacy for better integration of climate adaptation projects on the voluntary carbon market, etc.), microfinance, how to access Adaptation funds/Green Funds, etc.
• Becoming a MIT Solver will offer AVN a significant gain in legitimacy and visibility. We will mobilize the Solve community to help us promote our solution and fostering our communication efforts. In addition, we count on the Solvers to support us in expanding our network to connect with new potential partners (financial but also technical partners), political actors to help us gain in influence to advocate for a decent housing in Sahel but also for high added value carbon credits offering mitigation benefits as well as adaptation ones (cultural, economic, environmental, etc.).  We would also need support from the community to identify international or strategic events we should participate in.

We feel MIT could be the community and “stamp” we would need to successfully achieve this new step of our journey.

As mentioned above, housing is a major problem addressed rarely or not at all by public bodies. To date, there is no other organization than AVN promoting widespread decent, affordable and sustainable housing for the predominantly rural populations of the Sahelo-Soudanian strip.   

Various actors are involved in earth construction all over the world using various techniques. The frugal Nubian Vault technique and its adobe bricks are particularly economical compared to other techniques. For example,  compressed earth blocks (CEB) involve the capital cost of compressed earth block making machinery and mixing machines when adobe bricks only require a rectangular wooden mold (see picture below).

Secondly, most of the actors working on earth constructions have a project-based approach (some architects build extraordinary earth houses, but which are not designed to be widely accessible). AVN is the only actor in the region with a program-based approach aiming at disseminating an accessible eco-construction technique for the many and as quickly as possible: this is what makes our solution so innovative.  

A technical innovation

AVN’s first innovation was to simplify the Nubian Vault technique so it could be taught and appropriated by illiterate masons. The nubian vault is a 3000 age-old architectural technique originating in Upper Egypt and historically unknown in other African regions. This technique was identified by the NGO Development Workshop in the 1980’s as a potential solution to the serious housing problems of the populations of sub-Saharan Africa. From 1998 onwards, AVN started to investigate the technique again, with a view to simplifying and standardizingit so that it could be more easily adopted by local populations. After a series of technical trials in Burkina Faso, a streamlined method was evolved – the Nubian Vault (NV) technical concept – adapted to the climatic conditions and traditional know-how of the Sahel, easy to implement and ready to be adopted on a large scale.

The NV technique is thus ancestral and innovatory, both from its origins and its potential to respond to current and future challenges (population growth, climate change, desertification etc). Its many advantages make it nowadays the most promising construction technique for responding to the challenge of affordable and sustainable housing in Sahelian Africa.  

A market-based approach

As detailed above (in the section What is your solution), AVN has always applied a market-oriented approach, thus ensuring the relevance of its solution - if Sahelian families are ready to pay for NV houses it validates the solution, unlike a donated house - and creating the endogenous and sustainable engine behind the dissemination of the NV concept.  

A scalable business model

Summarized above (in the section Why are you applying to Solve) and detailed below (in the section What is your business model), AVN has recently defined a new business model to finance cash incentives for Sahelian families willing to build a NV house, through the sale on the voluntary carbon market of carbon credits generated by NV constructions. The more houses are built, the more carbon credits are generated to be sold, the more revenues can fund the construction of new houses, and so on. It should lead our program reaching self-funding in five years, while ensuring a 10% growth a year for the years ahead. Therefore, AVN’s funding strategy will gradually move from institutional development funds – our main funding for the last 20 years - to autonomous self-funding based on carbon credits trading.  

A community-based approach

Also described above (in the section How are you and your team well-positioned to deliver this solution?), our bottom-up approach is the cornerstone of our program enabling us to be as close as possible to the community we are serving. The Sahelian rural populations we are working with are both the producers of the NV houses (the mason and his apprentices) and the consumers (the family living in the NV or the communities using the NV buildings – agricultural storage, schools, health centers, etc.). Designed to be easily transferred to local actors (community-based operators), our territorial dissemination methodology enables the program to be replicated in all the countries of the Soudano-Sahelian strip, and maybe one day in other regions of the world facing the same issues and climate conditions.  

A test and learn approach

Since its beginning, AVN has adopted an iterative and continuous improvement approach, testing new solutions on the various components of the project. Fed with the feedback from the field and the discussions with other social entrepreneurs and actors from the development community, AVN is continuously creating and testing new tools to strengthen the program and multiply its impact. In 2016, following the example of the use of financial market incentives for environmentally positive products (e.g. in the construction and transport sectors) in Europe and North America, AVN started testing the use of financial incentives to overcome the financial barrier, by covering 70% of the necessary cash (representing 15 to 20% of the total cost of the house as most of the cost is provided in kind by the client - raw earth bricks and unskilled labor). Our dissemination methodology was completely redesigned in 2018.  New training materials for the masons and for our operational partners are regularly added to our catalog. We are constantly designing new funding mechanisms: microfinance product for access to new housing, financial tools based on carbon offset funds, banking product for access to green housing, etc.   

All of this combined with our 20 years’ experience should enable our program to gradually change the construction market to provide widespread decent and sustainable houses at the same time as green jobs and revenues contributing to the development of the region.

Our vision is to have a mature sustainable eco-construction sector in the Soudano-Sahelian strip, autonomous and able to operate without external funding nor AVN support and coordination.   

Our impact goals are:

• Decent, sustainable, and comfortable housing for the many, in particular the poorest, enabling better living conditions

• Employability, jobs and revenues for the local rural population

• Reinforcement of the local economies

• Climate adaptation and mitigation  

Our proven exponential growth allows us to be optimistic:

• In 2000 AVN was building 10 NV houses a year, 
• in 2010 we were building 100 a year, 
• in 2020 we are building 1,000 a year, 
• and we are confident we will reach 10,000 a year by 2030. 

See more indicators in the next section  

To achieve these impact goals, below some of our priority actions:  

For the next five years:

• As the distribution of financial incentives to the Sahelian families has been identified as the major lever for growth, AVN will run a five-year project to build a carbon offset-based financing mechanism to sustainably fund these incentives. Our projections allow us to estimate self-funding from year 6 (see our Business Model section).
• AVN will keep extending its geographical area of intervention, opening new regions in the countries where we are currently operating but also in new countries like Togo, Niger and Tchad. We need to identify more operational partners to deploy the methodology in the field but also more donors to fund this expansion.
• AVN will design complementary modules for its training programs, especially to reinforce entrepreneurship capacity building for masons to be able to develop the market themselves and build sustainable social businesses. We also need to train some complementary profiles to support the masons in the client relationship for the formal market. AVN will also reinforce the training of its trainer masons.
• AVN will reinforce its advocacy at both regional and national levels. First towards northern actors for a better integration of housing issues in their development programs (they should stop funding inappropriate cement houses whose construction norms would not even be allowed in their own countries). Secondly, towards West African authorities to integrate the right to decent housing into their public policies. Local leaders, especially women, will be trained and accompanied to lead this advocacy.  

Next year, AVN will especially focus its efforts to:

• Run all the ongoing projects already funded.

• Keep raising funds to ensure our development and foster new partnerships.
• Start implementing a new carbon offset-based financing mechanism.
• Start developing the eco-construction market in Togo. 
• Reinforce our “Market tool” a digital database to ensure the follow-up and management of our activities (training, construction, carbon credits registration, etc.) enabling better data collection for monitoring and evaluation, impact measurement and reporting. A new software program will be developed pro-bono by the social entreprise Tutator.
• Reinforce the collaboration between our masons trainers and the local professional training centers in Senegal and Burkina Faso.
• Identify, convene, and start training a group of future local advocacy leaders.

AVN tracks a series of indicators that allow it to measure the evolution of the NV market and its associated impacts. AVN collects and compiles its data in its “Market Tool”, a personalized database. A system of monthly collection and feedback of field information from regional offices to national offices and then to headquarters is operational. This data is then processed and analyzed at headquarters, making it possible to provide elements of capitalization and management of the program.  

Over the first 20 years of activities, the results achieved are as follows:

• 53,000 beneficiaries
• 36 operational partners - Community Based Operators mobilized (farmers' group, women's group, etc.)
• 5,200 NV low carbon buildings constructed
• 1,150 trained masons and apprentices active (paid) in the NV construction market
• 4.9 million euros generated locally
• 140,000 t-eq of CO2 avoided
• 6 countries of action and 1,500 municipalities impacted
• 20 % average annual growth of the market over the last 10 years 

The results of the growth of the NV market in Mali and Burkina Faso have been remarkable, despite an increasingly tense local context (COVID-19 pandemic and security risks affecting larger territories): in the last two years, 30% of the total NV built stock has been realized, namely 1,800 completed construction sites. This shows that the need for this adapted solution has been fully recognized by the Sahelian populations.

Today, AVN notes that it is possible to greatly accelerate the growth of this market (and therefore its impacts) by distributing financial incentives to help families cover the cash necessary for the construction of NVs. If AVN manages to establish a sustainable financing mechanism for these incentives (see the Business Model section), a further change of scale could take place, allowing for an annual market growth of around 30% - 40% in these regions.

Based on the current maturity of the market, without financial constraints, AVN estimates that it could achieve the following impacts by 2030: 

• 300,000 beneficiaries
• 35,000 NV bioclimatic houses constructed
• 3,78 million paid working days for NV masons during the fallow season
• 700,000 t-eq of CO2 avoided

The Nubian Vault technical concept

Originating in Nubia (now Upper Egypt) and historically unknown in other regions of Africa, the Nubian vault technique enables the construction of buildings with vaulted roofs without timber framework or shuttering; it uses locally sourced raw materials and simple tools and requires only a basic level of technical competence. The most ancient mud brick Nubian vaults, in Luxor, are still standing over 3,300 years after their construction.

As mentioned above, this technique was identified by the NGO Development Workshop in the 1980’s and then simplified and standardized by AVN so that it could be more easily adopted by local populations.

The environmental impact of the NV concept is one of the least damaging of all the architectural techniques currently used in Africa. NV construction does not require any use of timber resources and reduces considerably the need for exogenous building materials with a high CO2 footprint, industrially produced and /or requiring long distance transport (steel girders, zinc metal roofing sheets, cement, sand, gravel etc.), attenuating the effects of climate change. 

Several comparative thermal measurement studies carried out since 2007 in Burkina Faso and Senegal confirm the subjective reports of increased thermal comfort made by NV clients. The good passive thermal performance of NV buildings is associated with a significant reduction in electricity consumption for ventilation and/or air conditioning.

The first comparative measurements of the thermal comfort of the various types of buildings and of the materials used for their construction, and the quantification of the resulting benefits in terms of CO2 equivalent reductions generated by the NV concept produced the following figures:

• a flattening of average annual temperature extremes of 5 - 7 °C;
• cold discomfort (temperature < 20°C) very rare or inexistent;
• extreme heat discomfort (temperature > 37 °C) significantly reduced as compared to a building with a zinc or concrete roof;
• the construction of a NV and its use over a 30 years period under acceptable conditions of comfort leads to a saving of 0,8 t eq CO2 per m2, as compared to alternative construction methods, of which 20 % is due to the construction process, and 80 % for usage;
• the replacement of traditional architecture using timber beams by a NV leads to the saving of 0,164 trees / m2, namely 4,1 trees for a NV of 25 m2.  

It is reasonable to estimate that, by 2020, the NV program has led to a reduction of 150,000 - 160,000 t eq CO2.   

In addition, it is worth mentioning that AVN is constantly working on additional technical answers to make these NV constructions suitable to various applications: floor building, large surfaces, solutions against erosion or to reduce maintenance etc.

AVN wrote and adopted a Code of Conduct on Prevention of and Response to Sexual Exploitation and Abuse in International Assistance since July 1, 2019.  

AVN also signed and follows the following charters and codes of conduct:

• "A shared ethic" Charter of Coordination SUD and its members (adopted in November 2019)
• Code of good conduct of the German NGO Welt Hunger Hilfe (adopted in November 2019)
• Code of conduct of the Swiss Federal Department of Foreign Affairs in the framework of the PAFPA project (signed in January 21)
• Code of conduct of the DRC - Danish Refugee Council (signed in May 2021)
• Code of conduct and ethics of AVSF - Agronomists and Veterinarians without Borders (signed in September 2021)
• Code of conduct the UNHCR (currently being signed)  

These codes include commitments such as “Fight against all forms of harassment, intimidation and exploitation”, “eliminate discrimination” or “promote gender equality”.  

Our team includes people with no or little schooling as well as graduates with Master’s degrees, ranging from 25 years-old to 80 years-old. In the field, we work with people from all local ethnic groups and religions. Our Committee of Directors is composed of three women and one man.  

The success of our program depends on the variety and complementarity of our team’s profiles, culture, stories and background, experience and expertise.  

Concerning the training courses to become a mason or an apprentice: firstly no educational level is required, secondly they are delivered in-situ, in the villages, which makes them particularly inclusive.  

Finally, AVN promotes the selection of women's groups in the key role of operational partner (to deploy AVN’s methodology) and advocacy leader (to integrate the right to decent housing in public policies). Indeed, women are best able to talk about the benefits of adapted housing on their family’s health and well-being. Moreover women are often in charge of expenditures associated with the family home, they usually bear the cost of the inappropriate imported building materials or the burden of repairs. In some regions of West Africa, they are also tradionally undertaking the rendering and decoration of the walls of their houses, and do the same for their  Nubian Vault homes. They particularly appreciate the comfort, durability and solidity of NVs, as they are the first to suffer from inappropriate housing.

Our development program aims at providing the rural communities of the Sahel access to adapted, affordable decent housing. To this end, we operate in Burkina Faso, Mali, Benin, Ghana, Senegal, and Mauritania to enable the emergence of an eco-construction market.  

The first customers of this market are the rural Sahelian families. To reach them, we identify and mobilize community-based organizations to become our operational partners. They will convene people from their municipality to sensitize them to the benefits of a Nubian Vault construction. To build a NV house, the future owner will bring 70% of the cost of the house in-kind, he will make the earth bricks himself and will mobilize a labor force to help with the construction. Then approximately 350€ will be needed in cash to pay for the salaries of the mason and his apprentices and the few materials like doors, windows, or waterproof sheeting. To support the families willing to build a NV house, AVN can provide a cash incentive (part of the funds we raise are allocated to it).  

Our second target group are organizations willing to build low carbon community-use buildings (schools, health centres, agricultural storage units, etc.). They are often NGOs or local public authorities. They are not an end but a means. Indeed, AVN’s mission is to provide a decent housing to the many. But if the rural market is more of an informal market, the community-use building market is a formal market that will foster and strengthen the market, providing revenues for the masons and opportunities for reinforcement training, as these buildings are often more complex (with an upper storey, stairs, sewage, electricity, water, etc.), leading to the professionalization of the sector. We reach this target group though our network in the development sector, by word of mouth, and by answering calls for projects.  

The masons and their apprentices we train are not our clients but our beneficiaries, they don’t pay for the training (it is even a paid training) and AVN does not take a commission when providing them with clients. They also are one of the major channels to reach clients. Therefore the program not only provides housing, but also jobs and revenues to the communities.  

AVN has chosen a market-based approach for the program to be sustainable and autonomous in the long term, but AVN does not position itself as an actor of this market but as a facilitator. We are not aiming at taking construction contracts to build houses, health centers, schools, etc. We work on the emergence of an eco-construction market and will support the demand for NV constructions to provide jobs for the masons we have trained. Occasionally, when AVN’s network of operational partners is not yet present in a region, AVN can accept and take a contract for a Nubian Vault community-use building to have a demonstration NV that could serve to sensitize the local population to adopt this architectural technique, and therefore kick-start the market in a new municipality.  

So far AVN has raised funds from public and private donors, mostly from development actors (See all our partners here). In addition, we regularly receive donations from private individuals ("Individual social investors"). AVN mostly receives donations and grants, but can also be chosen as sub-contractor (“Other” in the scheme below). For example, a NGO operating in the Sahel can apply for a grant asking, among other things, for funding to build low carbon community-use buildings, choosing AVN as subcontractor.  

 These funds finance:

• Our activities in the field enabling the emergence of an eco-construction market: mobilization and training of operational partners, sensitization to the Nubian Vault architectural concept and benefits, training for masons, distribution of financial incentives, mobilization of various stakeholders including public authorities, advocacy activities, etc. We also include the part of the grants we receive for the construction of NV rural houses and community-use buildings that goes to pay the masons (who are not AVN’s employees).
• Salaries and payroll taxes for the teams in France and in Africa (58 employees, including 9 in France and 49 in West Africa)
• Professional/Consultant Fees: it covers the fees from our accounting firm, external auditor, assessment and monitoring consultants, fundraising consultants, workshop facilitators, etc.
• Investment: it mostly covers the purchase of minor equipment such as motorbikes (for our teams in the field to move around), computers and phones.
• Indirect costs: it mostly covers the rent of our offices, and  some fundraising trips to attend international events from the development sector.

The scheme above is based on our 2019-2020 budget as our 2020-2021 accounting closing is till under progress.

Moreover, we plan to diversify our funding thanks to the sale of our carbon credits (issued thanks to the carbon reduction of our NV constructions). Concerning the business model of our carbon credit mechanism, our clients will be companies willing to compensate their gas emissions. We’ll target CSR (Corporate Social Responsibility) management to sell them not only carbon credits, but a whole communications operation to commit their collaborators and clients to carbon neutrality. The beneficiaries will be the Sahelian families willing to build a NV house, as the revenues from the sale of the carbon credits will fund financial incentives to help them pay for the necessary cash for the masons’ salaries. Our channels to reach the companies will be the online platforms trading carbon credits, and also a wide range of ambassadors (such as sustainable development and carbon offsetting consulting agencies, impact investment actors, social entrepreneurs’ networks, etc.). This is how we plan to become financially sustainable, as detailed in the next dedicated section.

To become financially sustainable, our plan is to finance cash incentives for eco-construction though trading of carbon credits.

Offering financial incentives to Sahelian families to encourage them to adopt Nubian Vault eco-construction projects

Today the main barrier to the development of the market in the countries where AVN is well implemented (Mali and Burkina Faso) is the financial barrier rural families - the key target group of the program – are confronted with. Around 70 % of the overall cost of a standard NV house of 25 m2 consists of contributions in kind (earth, water, rocks, transport, unskilled labour); the remaining 30 % is in cash (around 350 €), to cover the salaries of the NV mason and his apprentices and the purchase of fittings (doors, windows, gutters etc.). This amount, relative to the average family incomes in the region where paid work is rare, makes such an investment difficult or impossible to raise.

Just as in the wealthy countries of the North, where financial support is now available for adaptation of buildings (insulation, solar panels, heating etc.), it seems totally justifiable that similar mechanisms be deployed in those countries most exposed to the ravages of climate change.

AVN has clearly demonstrated that a financial incentive of around 250 € allocated to a family will overcome the barrier to taking a decision to build and will lead to a major scaling up of the NV market.  The multiplication of constructions then becomes a function of the number of financial incentives distributed and the production capacity of NV artisans and masons.  

Generating carbon credits from low carbon NV constructions

Given the absence of an existing quantification protocol, AVN has developed its own protocol for calculating CO2 emissions avoided through bioclimatic construction projects in the Sahel. This protocol was devised by MyClimate (www.myclimate.org), a specialist and globally recognised organisation in the field of voluntary CO2 compensation and offsetting measures.

This protocol provides a standardised approach to estimating the expected ex ante reduction of GHG emissions from construction of standard NV buildings in the Sahel. The protocol conforms to existing carbon methodologies and directives (CDM, GS, VCS) and to the principles of the ISO 14064-2 (2019) norm. The ex ante calculation is based on the expected life-time of a NV building, applying a suppressed demand approach.

It should be noted that this protocol assumes a forecast of reduction of emissions over a period of three decades (estimated minimum lifetime of a NV building) and is based on current data. It does not take into account the future evolution of factors influencing emissions reduction, for example increases in global warming.

Accordingly, AVN has calculated the emissions savings through NV construction according to different scenarios, establishing an average baseline scenario applied to all NV rural domestic and community buildings in Mali, Burkina Faso, Benin, Ghana and Senegal.

To conclude: a NV building of 25 m2 saves the equivalent of 20 t of CO2, as compared to a 25 m2 building with concrete block walls and a concrete slab roof (i.e.offering the same levels of durability, heat and sound insulation and weather protection as an NV building).  

High added value carbon credits

Our carbon credits are an exemplar case study matching adaptation and mitigation of climate change. Indeed, the Nubian Vault technique provides sustainable and comfortable housing adapted to climate change. At the same time, this adaptation would be accompanied by a significant diminution of greenhouse gas emissions linked to the construction industry, along with numerous other benefits:

• cultural (use of local and appropriate technologies)
• economic (creation of green jobs)
• technological (control over the demand for energy)
• environmental (preservation of ligneous ressources)  

Finance the cash incentives for eco-construction through trading of carbon credits: a virtuous circle

The carbon credits generated by the eco-constructions for Sahelian families can be valued on the voluntary carbon market and be of interest to various stakeholders who are voluntarily engaged in a process of reducing their carbon footprint. These players are increasingly faced with the obligation to demonstrate their contribution to the fight against global warming, and adopting a "green" positioning is becoming an essential marketing argument for them. AVN can provide specific information to stakeholders involved in purchasing or trading NV carbon credits via an interactive cartographic data-base on the AVN website with geo-localised photos and details of each NV building benefiting from financial incentives.

The voluntary carbon market offers the potential to create a “win / win” dynamic between Sahelian families and those involved in carbon offsetting. Today, experts do not seem able to predict the evolution of this market but in the face of the climate emergency, whatever its future shape and the evolution of its unspoken rules, it is obliged to evolve. It will be up to the actors who drive it to influence it to make it both credible and transformative, by broadening its field of action towards a "climate contribution" which would notably integrate the adaptation needs of the most vulnerable to climate change.  

To finance the scaling up of the NV market through carbon trading, various different simulations have shown that it would be necessary to reach a critical threshold volume of carbon credits equivalent to 1,600 NV houses built each year - a threshold that could be reached in five years.

From the 6th year, this scenario would lead to the ongoing self- financing of an increasing number of cash incentives. To reach his state of financial and operational equilibrium by Year 6, a five-years implementation phase is necessary.  This will enable investment in monitoring tools, initial marketing campaigns and a growing pump-priming volume of the mechanism (trading of NV-CCs and distribution of incentives).

This phase will also allow for progress in obtaining carbon certification which will strengthen the attractiveness of the NV-CCs on the voluntary market as well as enabling the setting up of a financial entity dedicated to the project.

The more houses are built, the more carbon credits are generated to be sold, the more revenues can fund the construction of new houses, and so on  

This new funding mechanism will sustainably self-finance these cash incentives through trading of carbon credits and therefore ensure the growth of the market where AVN is already well implemented. On the other hand, we will keep raising funds from development donors and private foundations to finance the dissemination of our methodology and development of the eco-construction market in new regions.

First our budget growth (below): In 2021, we greatly increased our budget from approximately 1.4 million to 2.5 million.

Second, the large range of 50+ donors who have supported AVN along the years: among them major donors from the development sector like the European Union, the French Development Agency, the Walloon Air and Climate Agency, Alwaleed Philantropies, the Geres, the Belgian Development Agency, Expertise France, the Ministry of Environment of Quebec, the Ministry of Environment of Senegal, the PATRIP Foundation, etc. -> See all our partners here  

Third, several operators have already acquired Nubian Vault Carbon Credits: to compensate their activities (World Habitat), to offer them on the carbon credits market (Planetair/SWEEP), or to include them in their compensation programs (Government of Québec – Coopération Climat Internationale / PCCI).

Finally, several partners and sponsors have already shown their support to fund the investment project to set up our new credit carbon trading-based business model (detailed above): including  the Fonds Français pour l’Environnement Mondial (FFEM), the French Ministry of Environment, and the United Nations Development Programme (UNDP). 

Even if our financial indicators allow us to be optimistic for the  future, we are conscious that we only are at the beginning of our  journey considering millions of Sahelian are waiting for affordable,  appropriate, decent low carbon housing. In the coming years, we will intensify our fundraising efforts with the objective to multiply our annual budget by a factor of three or four.