Alternative building technologies (ABTs) are not new. We have often seen the use of alternative building technologies in what is termed as ‘green’ buildings, highlighting environmental compatibility. For example, the City of Cape Town is now the official host to the world’s tallest building constructed of industrial hemp. Similarly, game lodges are constructed to align with green principles around eco-tourism. While ABTs have been used to show-case ‘green’ and/or sustainable architectural design they have also been used in small-scale developments and pilots, with examples from practice highlighting their use in the construction of public infrastructure such as schools, community halls, service centres and early childhood development centres, as well as, to a limited extent, affordable housing projects.

This begs the question: what are ABTs? and, importantly, how do they relate to the crises manifested in respect of the lack of affordable, safe and climate- resilient housing in South Africa?

As the name suggests, ABTs differ from conventional building materials and technologies in various ways. They comprise those materials not widely recognised and regulated by national building standards. Traditional building materials are often referred to as “brick-and-mortar construction” and are the most commonly used materials that are recognised within the regulatory framework for building and construction in South Africa.

ABTs are also referred to as innovative building technologies (IBTs) in that these either comprise non-conventional building materials or require non-conventional building or construction methods. Examples of alternative building materials include light weight concrete blocks (which may also incorporate recycled or non-recyclable plastic); sandbag technology; nature-based materials such as wood, earth, hemp and straw; and reclaimed materials (e.g. reused building and industrial waste). Alternative building methods include shuttering systems; formwork moulds or interlocking building blocks.

The benefits of using ABTs over conventional building materials or methods can be broadly grouped into three categories: environmental, economic and construction. Environmental benefits can include reduced wastage in the construction process; energy efficiency (and other improvements in building performance, which may also increase comfort); and, lower embodied energy and related reduced carbon footprint across the whole lifecycle of the material. Economic benefits can include lower upfront construction cost; improved long-term feasibility in terms of lifecycle cost; the potential for localisation of production and value chains (particularly opportunities to strengthen township construction value chains and stimulate job creation); and, potentially improved market value of built structures. Construction benefits can include ease of construction; reduced construction time and labour costs; the use of unskilled or semiskilled labour; and, lower maintenance requirements.

It is important to note that not all ABTS are made equal and that the use of natural, sustainable materials may not automatically equate with a more affordable result that lends itself to construction (of low-cost housing) at scale. Rather, research undertaken by Isandla Institute argues that there are certain criteria which could be used to evaluate suitability and sustainability in a localised context. To begin with, the extent to which an ABT contributes to sustainability and decarbonisation is a critical criterion. Related to this is the issue of local environmental suitability, which refers to the specific geo-and environmental conditions in which affordable housing is to be built. From an economic perspective, localisation (of sourcing, producing and manufacturing ABTs) and the extent to which these processes and construction contribute towards localised job creation also need to be considered. In addition, in the context of low-cost housing, the affordability, accessibility and social acceptability of ABTs become particularly important criteria. Finally, the extent to which ABTs enable incremental augmentation, particularly in the context of self-build housing construction, and affordable multi-storey construction to address urban density is also an important consideration.

Reasons for the low uptake of ABTS are varied and range from limited public awareness and social acceptance and lack of professional knowledge/expertise to costs and lack of accessibility. Potential challenges related to maintenance, incremental augmentation and multi-storey construction are also considerations. Critically, insufficient government / institutional support and lack of access to finance and housing insurance are key barriers to the uptake of ABTs.

Despite the identified challenges, there are examples of ABT use in the context of low-cost housing. This includes sandbag housing (in Mitchell’s Plain and Philippi, both in Cape Town, the use of Saint Gobain products in the Diepsloot People’s Housing Process, the LIFT (Lightweight, Improved, Fire-safe, Timberframe) technology in eThekwini and the use of building waste and on-site natural materials in the Mbekweni stonehouses in Paarl. In these cases, the alignment of a unique set of circumstances was required for these projects to take place, outside of the usual cost and time constraints faced by public and private sector projects. This highlights why sustainable ABTs, and ABTs more broadly, require a more enabling environment for their increased uptake and institutionalisation.

The current uptake of (sustainable) ABTs is mostly a function of market dynamics related to innovation: demand is low largely due to unfamiliarity, cost and accessibility of the product and/or technology, whereas supply is low and highly concentrated, rather than diffused. Also, the affordable housing market is diverse, so nuanced responses and strategies are required. If the use (and further development) of ABTs, particularly sustainable ABTs, is to be scaled up in affordable housing construction, an all-of-government and all-of-society response is required. Strategies that can be pursued by various stakeholders include fine-tuning regulation and policy, improving both public and professional awareness and acceptance, reducing costs and improving accessibility, addressing issues related to maintenance and suitability for incremental augmentation and multi-storey construction and, lastly, improving access to finance and housing insurance. Growth in the use of ABTs can, in turn, drive further innovation and funding for greener building technologies, thus better integrating these systems alongside conventional building material and methods.

To better understand the limitations, risks and opportunities, there is a need for ongoing sector-wide (and broader) dialogue, engagement and partnership between all role players. This includes the public sector, built environment professionals, ABT producers, researchers, higher education institutions, the private sector and, critically, the end-user: people who currently live in undignified, unsafe informal structures that offer scant protection from the elements, for whom ABTs can be transformative.