Are polystyrene homes a good option for Kenya's expanding housing sector?

Justus Opiyo lives in one of around 50 polystyrene houses in a new development in Kajiado County, southeast of Nairobi, and says it has a major advantage over his previous homes.

"Its temperature remains constant, even in extreme weather, unlike the houses I have lived in before," he said. It is a real refuge from the heat of the Kenyan summer from January through March, he added.

This relatively new construction technology, using polystyrene, is gaining a foothold in Kenya's fast-expanding housing sector. The panels for building are made of a light cellular plastic, a by-product of oil refining, which consists of mini spherical particles containing about 98 percent air.

To make houses, polystyrene foam is sandwiched between two slabs of steel wire mesh. Once these have been joined together, they are sprayed with cement to support and strengthen the walls.

The tiny air bubbles trapped in the foam mean polystyrene houses can control climatic conditions better than buildings made of timber or concrete. Because air is a poor conductor of heat, the house stays cool when external temperatures are high and warm when it is cold outside.

Romanus Otieno, an urban planning lecturer at the University of Nairobi, said construction with polystyrene is ecologically friendly as it uses very little water. That advantage outweighs the negative of polystyrene being derived from crude oil, he believes, especially in water-scarce urban and semi-arid areas.

For Dennis Muli, an architect with Gem Archplans in Nairobi, the most important green benefit of polystyrene is its lightness, meaning less wood is needed to support the building. That could help reduce deforestation, he said.

Otieno said a standard two-bedroom polystyrene house costs about $6,700, while one made of bricks can cost twice as much. The difference is mainly due to lower labor costs, as polystyrene is easier to move around and put in place, he noted.

Polystyrene homes are also quicker to build, which could play a key part in reducing housing deficits, he added.

In Ole Kasasi, a few kilometers from Kandisi where Opiyo lives in the privately owned housing development, is another polystyrene building, comprising 20 apartments on five floors.

They are among a raft of polystyrene construction projects started in Kenya by different companies, including apartments in the western city of Kisumu built by Malaysian firm Koto Corp.

But the technology has yet to be fully embraced by homeowners, tenants and other housing developers who remain skeptical about the strength of polystyrene panels.

Taib Ali, a mason at the Ole Kasasi project, is often asked, "When are you completing this paper house?" People believe the homes are fragile because polystyrene can be broken with bare hands, he added.

Mary Nkatha, who lives in a concrete home near the new building in Ole Kasasi, has yet to be convinced that polystyrene can hold the weight of a house for long. She fears it could fall down, and plans to wait and see how sustainable the buildings are before she would consider moving into one.

But architect Muli said polystyrene homes are just as durable as concrete ones, provided the correct procedure is followed during construction.

Polystyrene has been a major success in countries like Japan, where it has been used in small dome-shaped homes, he added.

Muli urged government and non-profit organizations to lead the way in advocating for polystyrene housing projects because they are cost-effective and relatively green.

But, as the technology is still new, there is a need for better workmanship to avert potential problems such as the collapse of poorly constructed buildings, he said. And there must also be a focus on how to recycle polystyrene waste from building sites and demolition, he added.

Koto spokesman Hillary Wesonga said his company had set up a recycling plant for waste polystyrene. It is not yet a major problem, as polystyrene construction is only just taking off in Kenya, but that could change in the future, he added.

Otieno said the cost of building needs to be reduced if polystyrene construction is to become a popular building method in Kenya. The polystyrene panels currently cost $21 per square meter, but the price should be halved to entice more homeowners and developers, he said.

"The essence of affordable housing is to make sure the poor get basic shelter and there is decongestion (of urban areas) – what is the point of building more houses that are economically out of reach for the poor?" he asked.

In addition, building policies in general should be reviewed so that contractors are obliged to incorporate green features such as rain-harvesting and harnessing natural light, he said.

And they must ensure the security and safety of buildings, especially at a time when natural disasters are increasing in line with more extreme weather linked to climate change, Otieno said.

In late April, during a heavy downpour, around 50 people died in the collapse of a residential building in Nairobi, which had already been condemned but was still occupied.

• Reporting by Benson Rioba; editing by Megan Rowling. This story originally appeared on the website of the Thomson Reuters Foundation, the charitable arm of Thomson Reuters that covers humanitarian news, women's rights, trafficking, corruption, and climate change. Visit www.news.trust.org.