Market opportunities and barriers to the uptake of low embodied energy building materials and components: the case of interlocking blocks in Johannesburg

. Maphumulo, Minenhle Yvonne Desiree
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The intensifying urbanisation challenge in the global south, coupled with the resultant need for housing calls for governments to re-think how they address related needs sustainably especially due to resultant GHG-emissions and climate change. In order to decarbonise housing development for the City of Johannesburg, this study argues that, as one of the most visible alternative building materials and systems (ABMS), interlocking blocks have the potential to contribute significantly towards low carbon homes provided that critical barriers to their diffusion are systematically addressed. Guided by a qualitative study approach and focusing on an existing business in interlocking blocks as a case study, a supply-chain framework was applied to identify the relevant actors and stakeholders from whom interview participants were purposely selected and interview questions were then articulated. Subsequent to data presentation and analyses, overall findings were articulated in terms of opportunities and barriers. In particular, the study finds that on the basis of their production and construction process, interlocking blocks confer significant benefits such as eliminating the need for conventional burnt-clay bricks which entail high embodied energy, saving on cement as a high embodied energy material as the laying of the blocks is mortarless, process of construction is significantly simplified such that low-skilled labour can be engaged, overall construction cost and time are significantly reduced thus enhancing affordability for homeowners and tenants. On barriers, the findings further indicate inadequate guidelines and incentives towards strategic promotion of low carbon materials. Negative perception of ABMS by various actors contributes to superficial cost comparisons by clients and professionals based on building material unit prices instead of the overall outcome holistically. Such perceptions also reinforce propensity to gravitate towards conventional materials. The study therefore concludes that even though most of the socioeconomic and environmental benefits of ABMS strongly resonate with national and municipal policies and goals, their uptake will remain constrained until supportive regulations and incentives are adopted in the construction sector, especially with regard to reducing embodied energy while also facilitating innovation and green-skills in the sector.
A research report submitted in partial fulfilment of the requirements for the degree of Master of Urban Studies in Sustainable and Energy Efficient Cities to the Faculty of Engineering and the Built Environment, School of Architecture and Planning, University of the Witwatersrand, Johannesburg, 2022