Engineers Without Borders 2018 design challenge winners

Materials World magazine
,
26 Nov 2019

 

Engineers Without Borders is a global organisation that aims to help disadvantaged communities improve their quality of life through education and to implement sustainable engineering projects, while helping provide hands-on experience for engineers. The UK branch emerged in 2001 after University of Cambridge students were inspired by the Canadian branch to set one up locally.

The Engineering for People Design Challenge prepares students to become responsible engineers. It started in 2011 and has 6,500 students from 30 UK and Irish universities participating. The universities embed the initiative as part of their curriculum and put forward their top teams to the grand finals to showcase their solutions to industry judges.

For the 2018–2019 challenge, the brief was developed in partnership with Prakti, a social enterprise focused on the design, production and distribution of clean-burning, fuel-efficient cookstoves for poor families. One of Prakti’s primary markets is Tamil Nadu in Southern India – the location of the 2018 academic year’s task. The student teams were asked to discover more about Tamil Nadu and propose engineering interventions that could make a difference in the areas of waste management, sanitation, water, energy, the built environment, digital and transport.

Of Tamil Nadu’s 72 million inhabitants, 37 million live in rural areas, so the task focused on the rural communities. Tamil Nadu’s rural population has been steadily increasing in the last few decades and is expected to continue, as agriculture forms a part of the region’s economy.

The student teams were asked to rethink rural life and propose interventions that underpin aspirational lifestyles and address the impact of poor water and sanitation provision, a lack of waste management, limited transportation and digital infrastructure and unreliable energy provision.

Women’s community centre

The winning project in 2018 was for a women’s community centre by a team from Leeds Beckett University, UK. The project focused on the built environment, and involved researching the importance of such a facility within Tamil Nadu, including what the most effective design would be and what materials should be used to build the structure.

The design team’s concept aimed to give women a place to thrive, learn new skills, enjoy new hobbies, and feel safe. The building’s internal spaces would also be reconfigurable, for example into a lecture hall or a space for a GP surgery. The site would include a pour flush twin pit latrine for the toilet, a vegetable patch, a kitchen, and play areas. The material choices used for the design should be sourced locally, for practicalities as well as to help with employment and training opportunities. Style was a big influence in the building’s design. Pucca and kacha are the two main types of buildings in India – the former meaning solid and permanent, referring to structures made of substantial materials like cement, bricks, concrete or timber which are typically found in developed conurbations.

In contrast, kacha houses are viewed as less permanent, being made of natural raw materials such as mud, straw and grass.

Pucca-type buildings are culturally aspirational in the region, as well as being resilient to inclement weather. But they are also made of materials that are more costly, and often do not have basic facilities such as toilets, water supply and a kitchen. There was a need to find alternative building solutions that embrace the relatively low cost of locally available and sustainable construction materials found with kacha that can also provide a finish of pucca quality to satisfy the wants of the local population. To resolve this, bamboo was chosen for its strength and availability. While the material is considered non-pucca, it has many advantages, such as that the plant-based fibre absorbs the same amount of carbon dioxide from the atmosphere as it releases during harvesting.

It holds two to four times more compressive strength than wood (between 40–80N/mm2), is relatively light and can be used for many purposes. Its properties make it suitable for foundations, flooring, walls, roofing, scaffolding, water piping, shuttering and even the re-enforcement of concrete. Also, India is the second-largest producer of bamboo in the world, after China. The yearly bamboo production in the country is estimated at around 3.23 million tonnes, which makes it easily accessible in India and cheaper than other construction materials.

A 37m2 house in Tamil Nadu, which costs INR1,750–2,000 (£19-22), with conventional materials can be built for INR1,250 (£13.6) if bamboo is used.

To help make the building appear pucca, the bamboo structure could be covered with rammed earth walls, which are made by compacting moistened subsoil into place between temporary formwork panels. When dried, the result is a dense, hard monolithic brick.

With the materials combined, they would offer a portal frame building with a core structure made from contiguous bamboo poles that can double as an air cavity when surrounded on the inside and outside by a cement-bound rammed earth wall. Using pucca materials externally, these costlier elements would contribute to the aesthetic and not structure and thus, reduce cost. This design allows for a range of finishes to be selected, from the optional pucca materials.

Material testing

In order to test the materials and their suitability for such application, the design team made rammed earth cubes with materials readily used in India for building. The first step was to make clay powder. Lumps of clay were dried overnight in an oven, before they were crushed by hand and ground down to a fine powder of similar consistency to cement.

The method for cube making, according to BS1377-2, was that each mix should be made by adding all dry components to a cement mixer and letting them combine for around eight minutes. Water is added in increments and allowed to further mix for around 10 minutes to guarantee a thorough distribution of moisture.

Using 100mm cube moulds coated with oil, filling is done in three layers, each containing about 750-800g of mix, which is then compacted using a 6kg steel rammer by dropping it from a height of about 300mm – according to NZS 4298 – at least 30 times, or when there is a change in sound made by the compaction process, as the dull thud turns into a ringing noise when the mix is sufficiently compacted. The cubes are then removed from the moulds and cured in a humid environment for three weeks.

The rammed earth cubes showed approximately 10 times the load capacity achievable before failure by using cement-bound earth compared than a normal mud brick. This indicated that buildings of a few storeys are possible with such a material and would allow for a better and more durable finish, at little more cost than a regular mud brick.

Cleaner cooking

A second project was ecoPit – a cooking solution to address the smoke and carbon monoxide emitted from traditional stoves, or chulhas. Thiswas presented the People’s Choice Award. Developed by entrants from Heriot-Watt University, Dubai campus, the smokeless design controls the airflow and, according to the students’ submission, ‘uses the principle of secondary combustion to ensure complete combustion of the fuel used’. A mould would be built and distributed to villages, from which multiple clay pits could be made.

According to the students, burning biomass and fuelwood for cooking and heating is a major contributor to air pollution in India. Chulhas are commonly used for cooking and may be used up to three times per day. Respiratory and eye diseases equivalent to what a person may experience if smoking 20 cigarettes a day may develop in such houses. It is reported that chulhas can be linked to 25% of all pollution-related deaths in India.

This new smokeless stove design has a fire at its centre. Its double wall arrangement forms a channel that supplies air to the top of the stove. Fresh air flows into the channel through holes from the bottom of the outer wall. The air within the channel becomes hot as the fire heats the inner wall.

Meanwhile, that part has holes at both ends, which allows the hot air from the channel to enter from the top and rise, and fresh air from the bottom. The oxygen fed to the fire through the top of the inner wall contributes to
the secondary combustion step by reigniting smoke particles, resulting in a more complete combustion process within the stove. A lid restricts airflow within the stove so the rate of fuel consumption is reduced, and also acts as a stand for pots and other cooking utensils. 

Clay was chosen as the material to make the pots due to its heat storage capacity, durability, and availability in Tamil Nadu. The cost of production of the ecoPit is INR100–200 (£1.08-£2.16). The clay used for manufacturing is easily available in the villages and clay working is one of the more common professions. The funding for production can be obtained through fundraising events where prototypes of the ecoPit can be used to cook food for the villagers. The pit design is at a concept stage.

Empowering people

The Engineers Without Borders challenge empowers both communities and student engineers to not only maximise material knowledge, but to create solutions that are economically viable, develop employment opportunities and expose all parties to the commercial reality of production. For 2019–2020 the Engineering for People Design Challenge has expanded so that students in the USA and South Africa can also participate.


Charlotte Trick is Engineers Without Borders Communications and Marketing Coordinator.