Lying on the bed in post-surgery recovery, 60-year-old Veronique Jacquemain kindly looks at the busy girl preparing meals for her. Living under the same roof, they are not related, but mere roommates.

Having lost husband and separated with her children who lives their own, the retired nurse lives alone in her empty nest in Mons, a Belgian city. In order to fill the house with vitality, she decided to participate in "intergenerational home-sharing", in which a young stranger is welcomed for a small rental charge. In this case, the former stranger is Florine Patrelle, a French student studying speech therapy.

Two years on, their relationship is more like that of close friends than traditional landlord and tenant.

"We shared so many pleasant moments! We laugh a lot together and my children are satisfied and reassured that I have a company," said Jacquemain.

Patrelle is also well integrated into the family. "We get along really well, it's reassuring to have someone to confide in, and it works both ways. It's really great," she said.

The idea of home sharing originated in the United States in 1972, then spread over the world. These programs typically match the older householders with young homesharers. The youths, usually the university students, spend time with the elder in exchange for the low rent.

The practice was imported to Brussels in 2009 by Claire de Kerautem when she set up the nonprofit association 1Toit2Ages ("one roof, two ages").

"I was familiar with the idea in France, and when I arrived in Belgium 12 years ago, it didn't yet exist. I thought it would be a good idea to start, so I contacted the mayor and universities to get support," she said.

"The seniors live alone, even if they have children, because their children are working far away. It's secure if there is someone in the house. And to students, the rent is lower than the market price," she explained.

Last year witnessed 432 matches of seniors and youths via 1toit2ages, and the total number during the past 10 years exceeds 2,000, with an average annual increase in matches of over 20 percent. Starting in nine cities, the program has now spread to nine cities including Namur, Liege and Mons.

The initiative has been supported by the Brussels government. Celine Fremault, Housing Minister for Brussels, said as part of the public housing policies, 350 new intergenerational houses have been under construction.

"In this city, home-sharing is gaining momentum. We want to promote a well-proven model," said Fremault.

According to the 2018 aging report published by European Commission's Directorate-General for Economic and Financial Affairs, the EU is "turning increasingly grey in the coming decades". The total population in the EU is projected to increase from 511 million in 2016 to 520 million in 2070, while the working-age population from 15-to 64-years-old will decrease significantly from 333 million in 2016 to 292 million in 2070 due to fertility, life expectancy and migration flow dynamics.

"Most senior citizens with caring needs receive subsidized professional long-term care in their own homes. Given the aging of the population, the largest challenges in this context are to make sure every senior receives adequate care, while at the same time containing costs," said Karel Van den Bosch, an expert in the Federal Planning Bureau.

Due to the overall aging trend, the model of intergenerational home sharing has also resonated in other European countries, including France, Britain, Spain and Austria, according to Homeshare International, a network of professionals worldwide who run home-sharing programs.

Chen Wenxin and Dong Yuwen contributed to this story.