Environmental sustainability in township construction

The construction industry as a whole is a major consumer of non-renewable resources and a significant creator of waste. 23% of air pollution, 40% of drinking water pollution and a staggering 50% of landfill waste are generated by the industry globally¹. It accounts for 40%-50% of CO₂ emissions globally, of which South Africa is the 13th largest contributor². Evidently, the construction industry is one of the most unsustainable industries globally and in the low-cost and less formal township construction industry, this is even more apparent.

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In the township environment in general, environmental issues aren't often a priority, given the number and scale of more immediate and sizeable issues such as food security, safety and economic wellbeing. In the affordable housing and backyard rental sector, economic limitations restrict the use of environmentally responsible construction methods or low energy-use solutions.

Construction budgets do not allow for extra expenditure on innovative materials and township construction companies usually work only with low-cost, traditional materials. Over the past 4 years, as innovative, cost-effective materials have become available locally, we have been able to improve our rental flat specifications to introduce environmentally responsible materials where possible.

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The flats, which to the tenants and homeowners have the same aesthetic qualities as conventional flats, provide improved physical specifications at only a 3% increase in the cost of materials. These improvements have largely been focused on replacing conventional aggregates used in the production of concrete and bricks for the foundations and walls with recycled eco-aggregate alternatives. Resin8, a plastic-recycled aggregate made with mixed plastic waste, is used in the mixture of concrete for our foundations and bricks.³ Envirolite blocks, which incorporate recycled polystyrene that has been shredded in the concrete mixture, are used for our rib-block first floor slabs.⁴

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Sand, the third most consumed resource globally⁵, is in increasingly short supply and its removal from the environment has major consequences. In traditional construction, 0,75 m3 of sand is used in one cubic metre of concrete⁶ and for brickwork, the ratio of sand to cement is 6:1.⁷

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In a typical Bitprop flat, taking into account the ratio of Resin8 and Envirolite used in the concrete mix, we have spared more than 225 m³, or 80 tonnes of sand and stone, in favour of 19.9 tonnes of recycled plastic and polysterene.

With the environmentally responsible solutions we’ve standardised on our properties, we utilise 750 kg of recycled plastic and 143 kg of recycled polystyrene per flat. In total,  plastic and polystyrene have been recycled across the portfolio, which equates to 19.9 tonnes of waste diverted from Cape Town landfills.

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Our flats use efficient design and window placement to reduce energy consumption, bypassing the need for artificial ventilation, heating or cooling solutions. Energy-efficient water heaters, internal LED lights and outdoor solar security lights further reduce energy consumption, while water-efficient shower heads and dual flush toilets reduce water consumption, saving on costs for our tenants.

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Our buildings use 64,3% less embodied energy (the total amount of energy used to produce a product) than traditional affordable housing of comparable nature, and 59,2% less embodied energy than our original, non-environmentally responsible designs (based on an EDGE⁸ assessment of two of our properties).

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The introduction of recycled materials has enhanced the structural quality of the flats and provided improved insulation and fire resistance, and reduced energy consumption. Less sand and stone is used during construction, and a reduced weight lowers the carbon footprint of transporting the materials and their impact on road infrastructure.

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Two of these materials are significantly lighter than conventional materials, and because they are locally produced within 20 km of all sites, the net impact on fuel consumption is also beneficial. Because these innovations require only conventional construction methodology to use, we’ve been able to minimise the training required and have introduced environmentally responsible materials to a part of the construction industry usually overlooked by such innovations. This has upskilled the construction teams we work with, providing them with knowledge they can use on other projects in the future.

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From a user point of view, the flats are not perceived any differently from conventional buildings, a key reason we have been able to make such changes in the township environment. Continued recycling awareness has been created in our communities through our community recycling team, in which local unemployed residents have been trained on recycling principles. Recycling collected once a week from properties in the neighbourhoods in which we operate is sold to Resin8, providing our recyclers with an income stream. The plastic sold to Resin8 is then used in the eco-aggregate that goes into the construction of our rental flats.  

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Our goal is to expand this to more areas and at a greater impact level. We are committed to taking the necessary steps to decrease the environmental impact of backyard rental flats by introducing standardised, large-scale environmentally responsible construction methodology to our flats across townships.