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.

 

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Embodied energy and embodied carbon – the tip of the iceberg

The ELITH project stepped away from the desk and ventured into the “real” world – as many research projects do, to gather data on housing types, popular building materials, and construction techniques.

As part of a pilot study; analysis of a 50sq.m four roomed house – determined as the predominant housing typology in the peri-urban and rural setting of Nkozi Sub County, Mpigi District – revealed walling, floor finishes and roofing as major energy consumers. Walling (burnt clay brick with cement sand mortar joints and in some cases plaster as render) had 45,569 MJ; floor finishes (ceramic tiles on cement screed) had 13,843 MJ and roofing (Steel sheet on timber supports) had 10,685 MJ. Walling emerges as an outstanding energy hot spot due to its extensive area and is therefore the most logical area to begin our investigations geared towards reducing the embodied energy of low-income housing.

It was determined that burnt clay brick is a common building material that is considered readily available, durable and relatively cheap. A review of the brick production process reveals that the traditional method for burning bricks in Uganda consists of stacking a large amount of dried bricks (up to 20,000) into a large pile with a tunnel opening at the bottom into which large quantities of firewood are introduced and burnt over a period of 24-hours. The pile is plastered with mud in order to reduce heat leakage. The described process results in unevenly baked bricks and 20% waste as the bricks closest to the heat source are over burned while those farther away are under-fired (Perez-pena, 2009.) Further more, locally produced burnt clay brick is often uneven, leading to thick mortar joints during construction and often, plastering of walls to achieve a finished look. These defects lead to an increased amount of cement use in mortar and plaster that contributes to increased embodied energy of walling, recall 45,569 MJ.

However, what is 45,569 MJ as identified for walling in real or relative terms?  How is this energy obtained, what are the impacts? Burning wood fuels brick production in Uganda, immediately raising concerns on the amount of carbon dioxide produced – this is the gas often cited in global warming and sustainability literature.  However, it must be noted that wood fuel is considered carbon neutral due to the carbon sequestered during tree growth. There are other impacts: deforestation and associated out-turns – to produce the 45,569 MJ, it is estimated that the equivalent of 4 fully grown mango trees were cut down; burning wood produces many gases that include nitrogen monoxide – although in small amounts, the gas is 300 times more potent as a green house gas than carbon dioxide, methane – 21 times more potent, and carbon monoxide; and, the respiratory health impacts levied on society due to smoke production.

In sight of these challenges, we question now, do we have a better alternative, how can we improve existing technologies, and what is the rate of uptake of new technology?  Well, there is a lot that could be fronted as possible alternatives, for now a list would include: improving aspects of traditional brick, and brick making technology to produce a higher quality brick with lower embodied energy; research on alternative masonry construction techniques that include: rammed earth, stabilised soil block technology; additives for improved longevity of wattle and daub; and the most suitable way of propagating these technologies.

Reference

PEREZ-PENA, A. 2009. Interlocking Stabilised Soil Blocks; Appropriate earth Technologies in Uganda, UN-HABITAT.

So, we set forth again to find out more; join us as we develop a guide on weighted alternatives that will protect our environment, earn you a saving and improve health and well-being in our built environments

Popular Building Techniques and Material Utilisation in Low Income Tropical Housing; A case for a sustainable materials selection toolkit

This post sets to make the case for a tool that has been born out of an interrogation of the complex construct that is housing. Aspects that may contribute towards improving the quality, and, reduce the cost and impact of construction processes on the environment are of particular interest. The blog post thus, focuses on building a case for the development of a sustainable materials selection toolkit.

Buildings and their use have been noted to be a major consumer of energy and materials. It is estimated that 40% of the world’s energy is consumed by buildings, during construction and operation. It is no surprise that worldwide, there is a growing concern on the need to manage the world’s available resources better as observed by increasing literature and mobilisation on the subject of sustainability. Studies and discussions though, with regard to energy use and sustainability in the construction industry are often pre-occupied with operational energy of buildings. However, improvements in construction standards, ever improving energy efficient appliances, zero carbon energy supply on site imply that the total whole life carbon foot print is getting smaller while embodied energy and associated emissions are becoming more important in relative terms. (Lane, 2010)

This situation, it can be theorised, is true for low-income tropical housing in Uganda, since there is little or no heating and or cooling energy load because of the relatively mild climatic conditions. Furthermore, the relative poverty of low-income households implies that the prevalence of heating, ventilation and air conditioning systems (HVAC) is low. It is therefore clear that in this context, appropriate material use and selection is important in the promotion of sustainability in the construction of housing.

The case for a materials selection toolkit as a part of efforts to sustainably contribute towards the development of low-income housing is made when one considers the fact that in Uganda, low-income housing is synonymous with slums and more accurately, informal housing. Informal housing encapsulates slums, squatter settlements, marginal settlements, spontaneous settlements, transitional settlements and other settlement typologies that exist without proper planning permission and outside of the formal construction sector. This marginal existence implies that housing is seldom procured with the assistance of professional help. Rather, construction decisions are often driven by a variety of factors — some of which are baseless, to say the least. A materials selection toolkit would provide various implementers (developers, designers, artisans, building and construction managers) and receivers (clients, users, and the general community) involved in the construction of buildings with a manageable method to select building materials in a structured, measurable, and meaningful way.

The proposed tool is intended to compare materials based on the primary sustainability indicators, that is, environmental, social and economic ramifications. The indicators are detailed into criteria that include: for environmental indicator – impacts and life cycle; for the social indicator – health and safety, taste and preference, and performance of the material; and cost of the material as the criterion for the economic indicator. These criteria are further broken down into sub-criteria, which are the factors that should influence material selection. These include but are not limited to toxicity, embodied energy, fire resistance, aesthetics, cultural influences, maintenance, acoustic properties and moisture resistance.

Information on various materials’ ability to meet the exhaustive sub criteria, in their utilisation in various parts of the building is being gathered and the proposed weighing methodology being tested. The expected outcome is a series of scores, with the most sustainable material garnering the highest points. This therefore serves as an easily applicable and useful tool from which material choice can be made with little technical knowledge.

References

Lane, T. (2010). Embodied energy: The next big carbon challenge. Available at: <Building.co.uk/embodied-energy-the-next-big-carbon-challenge/5000487.article> Retrieved: 15. July. 2014.

UN-Habitat. (2010) Uganda urban housing sector profile. Nairobi: UN-Habitat

Popovic, J. M., Kosanovic, S. (2009). Selection of building materials based upon ecological characteristics: Priorities in function of environmental protection. SPATIUM International Review. no.20 pp. 23-27