A retired engineer in Germany has come up with a solution to the shortage of appropriate housing for asylum-seekers as winter draws near: pre-fabricated concrete houses that can be manufactured and erected in just a few days.

Germany has seen an unprecedented 938,000 people fleeing war, poverty and persecution arrive this year. This has severely stretched the capacity for temporary accommodations in some parts of the country, leaving many refugees stuck in tents, gymnasiums or converted warehouses.

Authorities have tried to solve the problem by purchasing specially fitted shipping containers, but demand for those has far outstripped the supply.

Peter Goergen, a long-time expert on refugees for Germany's disaster relief organization THW, said the idea for concrete shelters occurred to him in the 1990s, when refugees from the Balkan wars streamed into Western Europe.

"Concrete can preserve heat," he said. "The other advantage of concrete is that it can absorb a lot of humidity, so the breathing air of the people in this container will be absorbed and released again during daytime, when the windows are opened."

Each container is about 15 square meters (161 sq. feet) — enough room for six people, or even eight at a squeeze, Goergen said Wednesday. The shelters cost between 10,000-to-15,000 euros ($10,590-$15,880) each.

A trial site with 54 concrete shelters is currently being erected in Bad Neuenahr-Ahrweiler, just south of Bonn. One of its first residents, 26-year-old Nurid al-Weesh from Syria, said the buildings were warm and comfortable.

Authorities across Germany have already ordered more than 2,000 concrete shelters, German newspaper Frankfurter Allgemeine Zeitung reported.

Goergen said the design could be modified for other climates too.

"Concrete shelters without insulation could very easily be erected in Africa, North Africa or southern European countries even easier than here," he said.