Architects David Cole and Louise McKillop were visiting schools on the strife-stricken Ma Sot border between Thailand and Burma when they hit their first design challenge. How to create a school building for a community that doesn’t own land – a school that might need to be relocated just months or weeks later?

The young husband and wife, who had quit their London jobs for voluntary jobs abroad, decided a mobile building would probably be the best option. The difficult living conditions they encountered prompted them to invent a challenge for intrepid architects. They set up a competition for mobile school designs and received more than 200 entries from around the world. Each design paid an entry fee – making the competition self-sufficient.

Cole and McKillop have not looked back. Their UK-based NGO Building Trust International has since held three more design competitions across the developing world. Last month 600 teams from countries as diverse as Iran to Nigeria registered for a challenge to design sustainable low-cost housing for Cambodia’s poorest – the 10 best will be built to mark of Habitat Cambodia’s 10 year anniversary and will be on display at Meta House from Thursday.

With Phnom Penh facing unprecedented urban and economic growth, there is a growing need for social housing, Cole said.

“There’s an influx for ‘unplanned settlements’ – the politically correct term for a slum . . . So there’s a real need for low cost affordable housing,” Cole said. “We want to do that sustainably, rather than [build] concrete bunkers.”

Taking into consideration changes of the Southeast Asian climate, the winning houses also successfully encompassed family life and the opportunity for small businesses – and it all had to be built for $2,000 or less.

With local NGO partners Karuna Cambodia and Habitat for Humanity, homeless families picked their favourite designs from a shortlist of 10, chosen by the Cambodian Society of Architects.

Standing a few centimeters high in white construction plastic, the model-scale houses incorporate a mixture of traditional off-ground timber stilt designs and clever engineering.

With more than 100,000 resettled people living in Phnom Penh, and low rates of property ownership, bulk affordable housing is a challenge that more will need to take up, Cole and McKillop say. Cole believes microfinancing loans, as practiced by Habitat Cambodia, are the best method for getting people into homes, but says there aren’t enough microfinanciers in the low-cost housing market. Corporate social responsibility initiatives are one idea.

“We have been to see whether we can get more investment banks. People who are interested in the high end residential – duplexes and complexes – to get these companies to start developing lasting strategies for low income families. There’s money to be made for these companies,” Cole says.

The NGOs have found one private company in Cambodia willing to sponsor the Meta House exhibition - real estate developers.

“We know there are issues about land,” Dan Parkes, from real estate company Hongkong Land, says. “We’re sensitive about that and if there’s low cost housing to help Cambodians own their own houses . . . the democratisation of house ownership is essential to alleviating poverty.”

The Future of Sustainable Housing in Cambodia opens on Thursday at Meta House.