VERNACULAR ARCHITECTURE: Advocating Volcanic Stone Construction as a Viable Alternative to Fired Brick in Mountainous Areas of Southwestern Uganda.

Keywords: Vernacular, Stone Construction, Sustainable development

The following discussion presents volcanic stone as a viable walling material in areas where it is abundant.  Kisoro, Fort Portal and Bushenyi located in Southwestern Uganda are areas endowed with abundant volcanic stone.  However, area residents still opt for brick walling despite the poor soils in those areas.  The poor soils produce lower quality bricks compared to the fired clay brick from other areas especially around the Victoria basin.  Natural stone possesses physical properties suited for structural walling yet in Uganda it is habitually specified for its aesthetic finish (floor surfacing and wall cladding).  In comparison to Compressed Earth Block (CEB) and Compressed Soil Blocks (CSB), stone has not been explored enough as a potential front-runner among sustainable walling alternatives.  Further, little is being done to empower local communities to meet their own aspirations as industry, economics and urban development conspire to interrupt the transition to sustainable development particularly with regards to how environmentally unfriendly materials like fired brick are propagated.

The use of stone in construction is not completely alien to our context.  According to Nnamdi (1997), stone construction in Africa dates back to over 10,000 years ago.  In fact, Shadmon (1996) writes that Stone was used for construction way before man ever started using metallic tools.  Stone construction in Africa was popular in hilly parts of Africa creating what was known as the “hill style”, Nnamdi (1997).  More recently, residents in the hilly areas of Bunyaruguru and Kasese have constructed and actually live in stone buildings as shown in Figure 1.  In parts of Kabale stone construction is evident in their stone garden perimeter walls, and stone cooking fireplaces.

Figure 1: Stone Cottage in Fort Portal and abundant stone in Southwestern Uganda

Fired brick is not indigenous to Uganda’s material palette, in fact it was never used, at least not until a century ago, when the biggest Cathedrals were constructed at Namirembe and Rubaga (Moon, 1994) under stellar supervision even during material production.  Today, the local brick industry is highly unstandardized and because of this there is an inconsistent quality of bricks most of which are irregular.  Further, some bricks are made from poor quality soils (locally know as kifufu) and are significantly weaker than the paying public expects.  Irregularities in brick configuration have led to the wasteful use of mortar as the masons attempt to deliver straighter walls. Additionally, weaker bricks contribute to heaps of debris noticed on numerous construction sites – a topic deliberated upon previously on this blog (see Building and Materials:  waste less, gain more, check the ecological footprint, October, 2015).

Indeed, potentially viable materials and construction techniques in rural societies are not being explored for their economic and environmental merit.  Unfortunately, architects in practice are not helping the situation.  Most architects in the country persistently avoid rural commissions because few, if any, people there can afford their professional fees.  As a consequence, the low-skill level fundis and draftspersons that take on these rural projects generally work with a standard brick palette as taught in technical schools.

The cost of brick construction is even higher in the mountainous areas of Southwestern Uganda, even worse, where good clay soils hardly exist.  As a result, bricks are transported large distances to service these areas further increasing the economic and environmental cost of construction.  Brick transportation in the popular small to medium gasoline trucks over rough roads could consume as much as 5MJ/tonne for every kilometre (Fraser et al, 1995).  At this rate, each truck on a regular 100km trip uses the same fuel equivalent to burning 100kg of charcoal.  Transportation delivers an avoidable carbon load of up to 0.0741 KgCO2 per kilometre (Quashning, 2016).

Reducing the cost of construction is crucial for the success of vital infrastructure such as access to housing. “The cost of an average home mortgage in Uganda is about $30,000” Muhumuza (2016).  However, according to the World Bank development indicators (2016), Uganda’s Gross National Income is $670.  On a monthly basis, that is an average of $56.  This means that on average a Ugandan committing upwards of 30% of their annual income to service a mortgage, would require 144 years for one to pay off the loan.  These sums are inflated when interest is compounded.  This indicates that even a middle-class Ugandan would need to spend well over 50% of their income to afford decent housing.  Yet still, low cost housing in Uganda is considered by Ministry of Lands, Housing and Urban development, to be that which doesn’t exceed more than 30% of the homeowner’s income (Muhumuza, 2016).

There are three dormant volcanoes in Southwestern Uganda and according to Shadmon (1996), in the eruption of a volcano, as hot lava reaches the earth’s surface, it quickly cools down, forming crystals of igneous volcanic rock.  Some of these rocks include andsite, basalts, purnice, and rthyolite.  It is important to note that any one of these stones have a higher compressive strength than the popular fired brick.  Take for example basaltic rock that is most abundant in these areas, has an uniaxial compressive strength ranging between 12-63Mpa, (Schultz, 2012) – which is higher compared to the average compressive strength of fired brick that ranges between 5-10Mpa.

Interviews revealed a general perception among residents that stone construction is expensive.  Stone is even referred to as the rich man’s material. Residents report that, stone construction requires a lot more sand and cement mortar than fired brick.  Also, due to low popularity of the material, skilled masons in the area are rare and expensive. Interviews further revealed that the construction process takes a long time owing to a longer duration required to dry the huge chunks of mortar.  The delicate process of laying the uneven stone to form regular walls, also contributes to a prolonged construction process.

The residents say that before the popularity of brick in the area, vernacular architecture was constructed using mud and wattle like in other indigenous communities of Uganda. However, unlike in other areas, people in Kisoro added small volcanic stones to the mud to create firmer walls.  The walls were then finished with chalkstone dissolved in water to create a smooth surface.  Today, there are few stone buildings in the area mostly owned by the rich.  The difference being that the wealthy use sand and cement, yet the rest use mud mortar.  However, the result is not sturdy and for this reason, some residents in search for better quality buildings opt for fired brick rather then use stone with mud mortar.

One good practice example in a similar context is Butaro hospital by MASS design group architects located in Butaro, Rwanda just a few kilometers from Kisoro with similar climate, terrain and abundance in volcanic rock.  This project made use of the local volcanic rock, but also is sensitising society through the quality of the physical structure, that there is potential in this long-ignored material.  As a result, a new industry of stone dressing, marketing and construction has been able to kick off in Butaro, creating jobs that otherwise didn’t exist as Benimana (2016) explains.  Similarly, the artisans who hand-crush stones for aggregates in Southwestern Uganda can be further commissioned to shape volcanic stone to more regular blocks that can be assembled with less mortar. Further, in this same context, there is an existing trade of hand-crushed stones for construction aggregates. Stone crushers stand a chance to make additional income from stone dressing like their counter parts in neighbouring Kenya.

Progress in material production comes down to equipping communities with the necessary knowledge and skilling.  Architecture Schools need to educate built environment professionals to be more open-minded and take pride in the heritage of this country, and the readily available materials or opportunities that our context has to offer.  This can be achieved by questioning how we build and who builds if we are to transform rural communities all over the world.

References

Ahimbisibwe, A., Ndibwami, A., & Niwamara, T. (2015). Rural (Low Income): Inspiring Communities to shape to shape their future. PLEA 2015 Architecture in R(evolution) 31st International PLEA Conference. Bologna 9th – 11th September. Ass. Building Green Futures. Bologna, pp. 62.

Ahimbisibwe, A. & Ndibwami, A. (2016). Demystifying Fired Clay Brick: Comparative analysis of different materials for walls, with fired clay brick. 36th International Conference on Passive and Low Energy Architecture (PLEA). Cities, Buildings, People: Towards Regenerative Environments. Los Angeles.

Benimana, C. (2016). Architecture That Serves The Community. Design Indaba, view on 30th October 2016. Available at: https://www.//youtube.com/watch?v=033UAUihl6w [Assessed 17 March 2016]

Moon, K. (1994). St Paul’s Cathedral. Namirembe. Karen Moon: Richmond.

Fraser, J., Swaminathan, S., and Thompson, L. S. (1995). Energy Use in the Transport Sector. Work Bank Project. Available at: http://www.tgaassoc.com/documents/energy-text&figures-dec2007.pdf [Assessed 12 November 2016]

Muhumuza, M. (2016). The low-cost housing myth in Uganda, Daily Monitor, viewed on 26th October 2016. Available at: http://www.monitor.co.ugbusiness/Prosper/The-low-costhousing-myth-in-Uganda.”688616-3370372-b5x62qz/index.html> [Assessed 10 February 2017]

Nnamdi, E. (1997). African Architecture: Evolution and Transformation. McGraw-Hall, United States of America.

Odongo, J. & Lea, J. (1977). Home Ownership and Rural-Urban Links in Uganda. The Journal of Modern African Studies, Vol. 15, No. 1 (Mar., 1977), pp. 59-73, Cambridge University Press.

Olweny, M. (2006). Technology and Architecture Education in Uganda, The Architecture Science Association

Olweny, M. (2007). Politics, Religion, and Architecture in Uganda, in Loo, s. and Bartsch, K. (eds) Panorama to Paradise, Proceedings of the XXIVth International Conference of the Society of Architectural Historians, Australia ‘and New Zealand, Adelaide, Austria 21-2a September.

Ochola, D. (2016). The return of the stone craftsman to Kenyan Architecture, David Ochola Architect. Available at http://davidchola.com/architecture/green-architecture/the-return-of-the-stone-craftsman-to-kenyan-architecture/ [Assessed 02 April 2017]

Quashning, V. (2016). Statistics: Specific Carbon Dioxide Emissions of Various Fuels. Erneuerbare-Energien-und-Klimaschutz.de. Available at: http://www.volker-quaschning.de/datserv/CO2-spez/index_e.php [Assessed 13 March 2017]

Shadmon, A. (1996). Stone: An Introduction. London. Intermediate Technology Publication Ltd.

Schultz, R. (2012). “Brittle strength of basaltic rock masses with applications to Venus.”, 21 September, 2012, Journal of Geological Research.

SSA: UHSNET. (2015). Challenges of Low Income Earners on accessing building materials.  Shelter and Settlement Alternatives: Uganda Human Settlement Network.  Available at http://www.ssauganda.org/index.php?option=com_content&view=article&id=116:building-materials-uganda&catid=83&Itemid=296. [Assessed 7 October 2015]

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DOWN TO EARTH EDUCATION: Incorporating Earth Construction in East African curricula.

Keywords: Earth construction, University curriculum, Changing attitudes

Earth has been an indigenous material widely used for construction in traditional societies; this rich heritage is still visible in Morocco, Egypt as well as in West and Sub-Saharan Africa. Today, the use of earth is regaining prominence in West Africa due to deliberate efforts like the Nka foundation (Earth Architecture, 2014). Proponents of earthen architecture in Uganda like Eng. Dr. Mose Kiiza Musaazi have demonstrated that it is simple, cheap; community centred and does not require sophisticated machinery. Further, it can prevent pollution, deforestation, and loss of biodiversity thereby presenting an environmentally friendly alternative to conventional materials. Earthen Buildings are characterized by low energy costs from cradle to grave and though they are labour-intensive, are suitable for third world economies where labour is cheap.

Such technologies are critical in developing countries like Uganda where socioeconomic growth can be enhanced by the integration of sustainable design practices, green buildings, waste and biomass valorisation and energy saving technologies; all key components of meeting the Sustainable Development Goals. Unfortunately, earthen technologies are not formally taught in Architecture schools or technical institutions around East Africa, and subsequently have not gained traction in the local construction industry. Furthermore, low literacy levels in the region leave the bulk of this awareness and its associated convictions with an informed few who seem to be confined to their institutions of higher learning.

Since in Uganda the urban formal sector supports 
a small affluent elite but the majority of the people exist in conditions of abject poverty in rural areas and in the urban informal sector, this discussion espouses the feasibility of the optimistic view that if economic production is modelled on the sustainable development approach, it is possible to eliminate poverty and improve social conditions while avoiding environmental problems (Sanya, 2007).  Therefore, suggesting social change that can stimulate economic growth, could gain more acceptance in the immediate and eventually in the long run.

It should be noted that earthen construction is becoming commonplace around the globe. Studies indicate that almost 30% of the world’s rural population even in the developed world, predominantly resides in Earth buildings (Pacheco-Torgal et al, 2012). Consequently, recently constructed earthen buildings can be found in Austria, Germany, France and most of central Europe (BASEhabitat, 2016). In addition, around 15% of the population in France resides in earth-walled houses while a significant proportion of houses in Australia’s Margaret River province are housed by unfired earth walls (Hall et al, 2004). In United States and Brazil earth construction has increased substantially over the years, largely due to the sustainable construction programmes. In Uganda, this revival has not taken hold; therefore, shanty wattle and daub structures in deplorable state are noticeable in many small towns and rural communities. Here we are not suggesting replacing the current construction efforts with earthen construction, but merely proposing earthen construction to augment access to quality architecture to promote well being on a larger scale.

Despite the global momentum in earth construction, adoption in Uganda is significantly low and according to researchers, this can be attributed to lack of awareness, training and education, principally on issues of architectural design, sustainable practices and utilisation of environmentally friendly building materials. According to Ali et al., (2010) the lack of a sustainable architectural curriculum for higher educational institutions may be responsible for inadequate integration of Earth Construction Techniques. Detached from the ferment of epochal change, the groves of academe are failing to engage with current critical realities (Buchanan, 2012).

This section of the Blog is informed by data collected for chapter 6. Influencing Architecture Education of a PhD thesis Investigating the Process of socialisation in Architecture Education Through Experience in East Africa. (Olweny, 2017).  The thesis provides much-needed context on education and Curriculum in the region.

Observations of 3rd, 4th and 5th year level form universities in Uganda, Kenya and Rwanda, despite living in poor low-tech context, do not depict the reality of their socio-economic or even technological context; students’ material proposals did not seem to consider existing evidence of the negative impacts associated with material production like deforestation, excessive soil extraction, energy intensive production, and high construction waste. Further, students did not portray any sensitivity to the doubled charcoal prices in the last five years, thinner and sparser woodlands along major highways or even to rising costs of electricity. Student design proposals generally recommended exposed glazed facades on concrete or steel structures with fired clay brick or concrete block walling. These proposals lend limited credence to any adoption or integration of sustainable practices or suggestion of practical technologies to foster more efficient use of energy and locally available resources. This negligent attitude does not engender conscious interrogation of all the available options, or even re-visiting the merits of any indigenous earthen strategies.

Further, Olweny (2006) asserts that most architecture schools in Uganda are making no efforts to involve technology as an important aspect of architecture design. This has resulted into minimal efforts by architects in practice to research or creatively adopt new ways to improve design or to interrogate vernacular materials. In addition, even the schools that incorporate technology in the student’s design process, have their efforts let down when graduates go into the field and become negatively influenced by architects with contrary education, field or construction experience. The result of this is architecture that is not primarily informed by its context. Ironically in Uganda and even more in the region, foreign architects are undertaking most contextually responsive commissions.

Rigid reference to concrete, steel, cement and fired brick disregards the responsibility of universities to train/skill innovative minds to devise contextually relevant solutions. It should be noted that competent educators in this area are hard to come by, and those who are, perhaps are either too busy in practice or would not settle for the terms on offer. It is also unfortunate to note that during mandatory field experience (Industrial placement) engagements on construction sites, students are exposed to bad construction practices. This exposure creates a negligent and haphazard attitude or approach towards the construction process.

On the whole, architecture education in Uganda does not prepare professionals to support or confidently survive within their context. Students become proficient primarily at interventions that are convenient for a minority of the developers, yet constrictive to the larger population that is struggling against poverty. Architects trained to serve a privileged few, miss the opportunity to drive a transformative engine towards more sustainable cities and communities.

The Faculty of the Built Environment at Uganda Martyrs University despite all the above challenges always attempts to improvise. One recent effort was an elective that explored the dynamics of construction and its links to the iterative process that is design and the quality assurance/control processes in testing and guaranteeing building materials. See Figure 1 below.  The focus was key walling and roofing options that fulfill specific embodied energy and functional requirements while revealing an aesthetic often lost either due to poor building technique or utter negligence that leads to material wastage. A central consideration was the ability and interest in working as part of a team in an effort to collectively hone key skills. Ultimately the goal was to interrogate the question: Can stepping out of the studio to engage construction in real life improve students’ perception, grow their aspirations and nurture key values?

Figure 1. Peer learning and collaboration during the construction of the Earth Kiosk and Pizza Oven

Brim’s (1996) classical definition of socialisation as “the process by which persons acquire the knowledge, skills and dispositions that make them more or less effective member of society”. Architecture schools should endeavour to deliver a critical blend of tacit alongside explicit knowledge. This blend engenders attitudes of responsibility for self-development, critical thinking, and professionalism. These attitudes contribute to much-needed values of self-expression, confidence as well as critical self-appraisal that make a competent Environment design professional.

This study suggests that deliberate approaches, even at a small scale, to incorporate earthen construction into university architecture curricula can increase awareness and application of locally available materials in construction. Such projects could stimulate inter-university or inter-disciplinary collaborative efforts between universities and attract funding for future research projects. Further, the study identified challenges that might help inform coordination and planning of such projects.

References

Agapiou, A. and Salama, A, M. (2016). Shaping the Future of Architecture Education in Scotland. Charrette, Volume 3, Number 1, Spring 2016, pp. 1-5(5). association of architectural educators (aae). University of Strathclyde.

Ali, D., Gumau, S.W. and M. Ajufoh, M. (2010). “Towards A More Sustainable Architectural Curriculum Of Higher Institutions In Nigeria.” Journal of Research in Education and Society. 1 (2-3).

BASEhabitat. (2016). “Earthen Architecture in Central Europe.” Travel Guide www.basehabitat.org. University of Art and Design Linz.

Bobbo, H., Ali, A. M., Garba, I., and Salisu, M. (2015). The Prospects and Challenges of incorporating Earth Construction Techniques (ECT) in the Nigerian Educational Curriculum. Journal of Multidisciplinary Engineering Science and Technology (JMEST) ISSN: 3159-0040 Vol. 2 Issue 8, August. Avaible at: http://www.jmest.org/wpcontent/uploads/JMEST N42351008.pdf [Accessed 15 February 2017]

Bouchlaghem, D. (2007). Architecture engineering and Design Management. Teaching and Learning Building Design and Construction. London: Earthscan.

Buchanan, P. (2012). “The Architectural Review. The Big Rethink Part 9: Rethinking Architectural Education.” Available at: https://www.architectural-review.com/archive/campaigns/the-big-rethink/the-big-rethink-part-9-rethinking-architectural-education/8636035.article [Accessed 18 October 2016]

Earth Architecture. (2014). “Nka Foundation Announces the Winners of the Mud House Design 2014 Competition for Ghana.” Available at: http://eartharchitecture .org /?p=645 [Accessed 18 October 2016]

Elliot, W. (2003). Innovative Pedagogy and School Facilities. DesignShare, Elliot and Washor. Available at: http://www.designshare.com/Research/Washor/P edagogy%20and%20Facilities.pdf [Accessed 15 August 2016]

Guillaud, H. (2008). Characterization of Earthen Materials. In: Avrami, E., Guillaud, H., Hardy, M., editors. “Terra literature review – An Overview of Research in Earthen Architecture Conservation.” Los Angeles (United States): The Getty Conservation Institute; p. 21–31 Available at: https://www.filepicker.io/api/file /c8QIcAjRSuOvqHzchZUv [Accessed 18 Feb 2017]

Gürel, M.Ö. (2010). Explorations in teaching sustainable design: A studio experience in interior design/architecture.” International Journal of Art & Design Education. 29(2): p. 184-199.

Hall, M. and Djerbib, Y. (2004). Rammed earth sample production: context, recommendations and consistency.” Construction and Building Materials. 18(4): p. 281-286.

Hendricson, W. D. (2006) “Educational Strategies Associated with Development of Problem-Solving, Critical Thinking, and Self-Directed Learning.” ADEA Commission on Change and Innovation in Dental Education. Available at: http://ccnmtl.columbia.ed /projects/pl3p/ADEA%20problem%20solving%20review.pdf [Accessed 12 March 2017]

Moquin, M. (1996). Ancient solutions for future sustainability: Building with adobe, rammed earth, and mud.” Earth building and cob revival: A reader, 3: p. 7-12.

Ndibwami, A. & Ahimbisibwe, A. (2016). ENDS 3501/2501 Demystifying Construction: Let’s build! Elective Course Unit at the Faculty of the Built Environment, Uganda Martyrs Unversity, Nkozi

Olweny, M. (2017). “Socialisation in architectural education: a view from East Africa”, Education + Training, Vol. 59 Issue: 2, pp.188-200, doi: 10.1108/ET-02-2016-0044. PhD, Welsh School of Architecture, Cardiff University, Wales.

Pacheco-Torgal, F and Jalali, S. (2012). Earth construction: Lessons from the past for future eco- efficient construction.” Construction and building materials. 29: p. 512-519.   Available at: https://repositorium.sdum.uminho.pt/bitstream/1822/16 367/1/JCBM2998.pdf [Accessed 24 March 2017]

Radford, T. (2011). “Learning and Teaching Academic Standards Project.” Architecture. Learning and Teaching Academic Standards Statement. Ch. 3. Nature and Extent of Architecture. Australian Learning and Teaching Council. P.8

Available at : http://disciplinestandards.pbworks.com/w/file/fetch/52867943/ altc_standards_ARCHITECTURE_240811_rv3-2.pdf [Accessed 17 March 2017]

Sanya, T. (2007). Living in Earth: The Sustainability of Earth Architecture in Uganda. PhD thesis. University of Cape Town.

Schmidt, H.G., Norman, G.R., and Boshuizen, H.P.A. (1990). “A cognitive perspective on medical expertise: theory and implications.” Acad Med 1 990;65:611-21.

Shannon, S. J. (1995). “The Studio Critique in Architectural Education” PhD, University of Adelaide. p 392 Available at: http://hdl.handle.net/2440/18641[Accessed 15 August 2016].

Temple, N. and Bandyopadhyay, S. (2007). Thinking Practice. Reflection on Architecture Research and Building Work. London: Black Dog Publishing.

Is Fired Clay Brick All We Know?

In this post we carry on the discussion about environmental impacts and wastage associated with the fired clay brick. Owing to the general consensus that it is apparently the cheapest option, the fired clay brick has not left much room for consideration or evaluation of possible alternatives. We acknowledge people’s taste and preference of the fired clay brick; however, suggest that this walling material has become a victim of its own success. Therefore, alternative walling options that challenge this position would have a significant impact on construction practices in general.

Preliminary field evidence shows that contractors, even on large scale projects, generally opt for local artisan made fired clay bricks instead of the more sustainable factory-manufactured options in a bid to save money.  The danger associated with this decision is two fold: on one hand, the inefficient production process continues to strain local wood fuel sources, which contributes to deforestation and air pollution as discussed in the previous post. According to (NEMA 2002: 122), Uganda is experiencing rapid deforestation as to 3% of forest cover is lost per year due to unsustainable harvesting. Worse still, excessive quantities of mortar are used during construction due to rapid construction timelines, inconsistent brick sizes, negligence, and low mason skill levels (Figure 1).  As a result, vast quantities of plaster are required to deliver a smooth finish to these uneven walls. In some situations half-bricks or alucobond are used as cladding perhaps to hide the imperfections, evidence that concern over the cost of the brick was never a well thought through challenge.  Cement wastage in mortar and plaster cannot be ignored since cement production causes pollution and accumulation of waste. Further, according to UNEP (1999), manufacture of cement is the second biggest anthropogenic contributor to greenhouse gas emissions. It is one thing when fired bricks are used on small projects, however the impact is more significant when a noticeable lack of concern is prevalent on larger projects.

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Figure 1: Inconsistent brick sizes, unorthodox bonding technique and wasteful application of mortar.

Today’s discussion does not claim to provide a comprehensive solution on material selection since as Sanya (2007) attests, the global discussion embodies the difficult to reconcile aims of safeguarding human wellbeing (including alleviation of poverty) and preservation of the environment. Our discussion here merely sounds out that there are actual viable alternatives to the brick wall. Often times, the argument against alternative construction methods has limited information on cost and performance as compared to conventional methods. However, with more practitioners getting involved in this endeavour toward better buildings, irrefutable evidence of overall gains associated with alternative construction is emerging.

Indeed, production of building materials is an important economic activity. Raw material sourcing, production/manufacture, distribution, marketing and assembly during building construction are all sources of employment. Satisfying the economic need of the local artisans who are currently involved in fired clay brick production is a worthy consideration. As Sanya (2007) puts it, by relating the Ugandan poverty situation to deficiencies in the country’s architecture, the feasibility of the optimistic view that, if economic production is modeled on the sustainable development approach, it is possible to eliminate poverty and improve social conditions while avoiding environmental problems. Much like the fired clay brick makeshift kilns which are some times dedicated to specific projects, these blocks can be commissioned on project-by-project bases and even produced on the construction site on a need basis to minimize wastage. These blocks have low environmental load resulting from use of locally available earth that is not highly refined and use of local resources resulting in affordability and support to the local economy. Also they are adequate for the service life of most buildings. The concept of service life is useful in understanding durability. Service life is the actual period of time during which a building or any of its components performs without unforeseen costs or disruption for maintenance or repair.

Say, we compare fired clay brick with two unfired wall alternatives.  The alternatives include the Compressed Earth Block (CEB) and Compressed Soil Block (CSB). According to Perez (2009), compressing a humid mixture of soil and a stabilising agent in a manual or mechanical press makes the CEB. Note that variations (often in nomenclature) of the CEB include the Compressed Stabilised Earth Block (CSEB) and Stabilised Earth Block (SEB) while those of the CSB includes the Stabilised Soil Block (SSB). In an effort to increase structural stability of the wall as well as reduce bonding mortar, interlocking tongue and groove configurations are being adopted for these unfired earth/soil block options. The Interlocking Compressed Earth Block (ICEB) (Figure 2) and Interlocking Stabilised Soil Block (ISSB) are variations in this regard.

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Figure 2: Setup of Interlocking Compressed Earth Block

The CSB is favoured for this discussion because no cement is required during its production.  The CSB indeed is slowly gaining acceptance in everyday construction. CSBs are sturdy and are now being produced in different sizes and configurations to suit the design need. Further still, when an interlocking configuration in ICSB is adopted, no cement is required in the production or construction of the walling as opposed to conventional mortar bonded walls. Also, different soil types may be used together to obtain good CSBs, meaning less demand on clay; this is fortunate because according to (SSA: UHSNET, 2015), good quality clay products are gradually becoming scarce in Uganda. This is due to the limited availability of appropriate clay in the country whose demand has increased dramatically due to high demand associated with an enhanced construction sector. Further, on site production of CSBs means that they are virtually accessible anywhere and mechanically produced blocks can even be delivered with a guaranteed compressive strength and with lower CO2 emission during production. Owing to the high thermal mass of the block, there is an added advantage of cooler interior spaces, which is ideal for tropical climates where cooling governs the energy requirements. CSBs are known to be susceptible to weather damage; however, a resin membrane can be applied onto the walls to improve resistance to moisture.

The second option, the CEB has been used with a significant degree of success in upgrading informal settlements in Uganda (Sanya, 2001). It is highlighted in this post because it represents a modern approach to building with earth in Uganda. While (in a related study at the Uganda Martyrs University) the CSB recorded a higher compressive strength than the CEB, Sanya (2007) also found the CEB more expensive than the fired clay brick wall, however, 30% of this calculated cost was dedicated to cement in the CEB mix. As such, without cement cost for the CSB, the wall type should cost considerably less than the fired clay brick wall.

We conclude that much as cost (and convenience) is what drives most people’s decisions, it is wise while considering the options available for wall construction, to consider a wider selection of factors that indeed will contribute to the combined social, economic and environmental benefits. The focus of our next post therefore will capture specifically how the CEB and CSB in their numerous variations perform alongside other walling options with regard to: Cost, Durability, Aesthetics, Embodied Energy, Site Specific Strategies, Self Build Strategies, Implications for Labour, Technology among other criteria.

References

Guillaud, H.,Thierry, J., Odul, P.,. (1995) Compressed Earth Blocks. Volume II. Manual of Design and Construction. Eschborn Germany: GTZ.

Sanya, T. (2007), Living in Earth: The Sustainability of Earth Architecture in Uganda, [Doctoral Thesis], The Oslo School of Architecture and Design, Oslo.

SSA: UHSNET, 2015. Challenges of Low Income Earners on accessing building materials. Shelter and Settlement Alternatives: Uganda Human Settlement Network. Viewed on 07.10.2015. Available at: http://www.ssauganda.org/index.php? option=com_content&view=article&id=116:building-materials-uganda&catid=83&Itemid=296

Perez, A. (2009) Mission Report, ISSB: Appropriate Earth Technologies in Uganda. Desaster Management Programme. UN Habitat.

UNEP (1999) (United Nations Environment Programme). Dioxin and Furan Inventories: National and Regional Emissions. Geneva: UNEP.