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.
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.
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.
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.