Research powers insights into sustainable housing

A groundbreaking national study led by the University of Cape Town (UCT) is offering new insights into how South Africans use energy in affordable and social housing – and what this means for the country’s sustainability future.

The study, led by Grant Smith, along with co-investigators Alison Highes and Richard Larmour of the Energy Systems Research Group (ESRG), forms part of a global project involving partners in Colombia and Indonesia, and is the largest study of energy and water consumption in residential apartments ever undertaken in South Africa. It combines large-scale data analysis, household surveys, and advanced monitoring to assess how efficiently different types of housing – from social to upper-middle income – use energy and water.

“We’re looking at everything from social housing, where residents receive a subsidy to rent their apartment, to lower- and upper middle-income housing, and even premium developments,” said Smith. “But our main focus is on affordable and social housing – the sectors where energy efficiency has the greatest potential to improve lives and reduce environmental impact.”

“This kind of work wouldn’t be possible without the computational resources we have at UCT.”

The ESRG team is using a mix of metering data, administrative records, and building characteristics to understand how different households consume energy. This includes data from a 10% sample of households, with about 6 000 apartments surveyed this year. Researchers will revisit these households next year to study how changing household dynamics – such as family size or income – influence consumption over time.

For a smaller sample of 900 apartments, the team is installing high-resolution sensors on geysers that record data at 30-minute intervals on geyser water and electricity use, indoor temperature, humidity, and even gas usage for cooking. “This level of detail helps us understand not just how much energy is being used, but where and why,” Smith explained. “It’s vital for improving building standards and informing future housing policy.”

The project relies heavily on UCT’s high-performance computing cluster and eResearch infrastructure for secure data storage and analysis. “This kind of work wouldn’t be possible without the computational resources we have at UCT,” said Smith. “We will be analysing enormous datasets.”

Building smarter, not harder

Smith said the research addresses one of the most pressing challenges facing South Africa and many developing nations: how to build adequate housing without exceeding environmental limits.

“In the developing world, including South Africa, we have to house a growing population in ways that promote human well-being. Residential apartment blocks are dense and make efficient use of limited space, so they are an attractive solution to house a growing population. However, we can’t continue building as resource-intensively as we have in the past. Our environmental budget is binding; exceeding it is like exceeding the laws of physics. It simply can’t be done.”

By comparing apartments built to the widely used EDGE green building standard with conventional residential units, the team aims to demonstrate the benefits of resource-efficient design.

The findings will inform developers, city planners, and policy makers about how best to balance affordability, comfort, and environmental sustainability.

“Our work in South Africa inspired similar studies in Colombia and Indonesia.”

The Cape Town metropolitan area provides a valuable case study, with its rapidly expanding residential developments stretching from the city centre into peri-urban areas. “Cape Town has seen dramatic growth in medium-density developments,” Smith said. “Many of these are part of our study, allowing us to compare how different design approaches perform in similar contexts. That said, we are also studying residential apartments, both EDGE and conventional apartments, in Gauteng, and KwaZulu-Natal, which lie in different climate zones, and face different challenges.”

Although the project is international in scope, South Africa plays a leading role. “We are the primary site for this global research effort,” said Smith. “Our work in South Africa inspired similar studies in Colombia and Indonesia. This allows us to compare results across very different urban and cultural contexts.”

The study builds on years of collaboration between South African developers, the International Finance Corporation, and UCT researchers. It represents a model of how academic research can directly inform sustainable development policy – both locally and globally.

Surprising pilot findings

Early results from the pilot phase have revealed some unexpected insights. While the physical design of resource-efficient housing seems to be performing well, many residents are not using their homes in ways that maximise comfort and savings.

“The surprising thing is that there’s a lot of welfare being left on the table,” Smith noted. “Residents could be saving more energy and money, but behavioural factors often get in the way. For instance, people might not know how to adjust their geyser settings or use their appliances efficiently.”

This behavioural gap means that even well-designed housing may not achieve its full potential without tenant education and behavioural interventions. “Engineering is only half the story,” Smith added. “We also need strategies that help residents fully realise the value of what they have. This can save them money and make their homes more comfortable.”

“We’re learning that sustainability isn’t just about technology; it’s about people.”

To address this, the team is incorporating behavioural insights into the main study phase, testing approaches that could help residents adopt more efficient habits. “We’re learning that sustainability isn’t just about technology; it’s about people,” Smith said.

For Smith, who trained as an economist before joining the ESRG in UCT’s Department of Chemical Engineering, the project represents an intersection of disciplines – energy systems, behavioural science, and social equity. “Understanding household behaviour helps us see where technical solutions meet real-world human decisions,” he said.

The study also contributes to broader debates about urban planning, equity, and climate change adaptation in the Global South. By revealing how people actually live and use energy, it provides evidence to guide both local and international housing policy.

“There’s still a lot of uncertainty,” Smith acknowledged. “We don’t know everything we’re going to find yet – and that’s the exciting part. The data will reveal patterns and possibilities we can’t yet anticipate.”

What’s clear already, though, is that South Africa is helping to lead a global conversation about sustainable housing for a growing urban population. As Smith put it: “This is another way for South Africa to contribute to global knowledge. Our work shows that we can build efficiently, affordably, and in ways that truly support human well-being.”