The White Oak Cottages program at the Fox Hill Village retirement complex on Longwood Drive opened in the spring. It is the first to use the Green House model for people with Alzheimer’s disease in the Northeast, and just the third nationwide, organizers say.

Each of the program’s two cottages has 12 bedrooms and as many private bathrooms. Residents share household tasks, such as cleaning and cooking, and sit down to eat with a staff that is in place around the clock.

The ranch-style homes contain open kitchen, living, and dining areas that all residents share, as well as landscaped gardens.

“These are real family homes with typical areas that allow residents to be independent and engage in meaningful activities,’’ said Tony Amico, the managing director of the Westwood facility.

“The setting tends to keep people more calm and at ease,” he said, which is the crux of the treatment model.

In an assisted-living facility or a nursing home, for example, meals are usually taken in a large communal room, Amico said. “Here, they eat family style at a long dining table where staff and even members of their own families can sit down with them,’’ he said.

The staff is trained in all aspects of daily life from menu planning to cooking, and residents are encouraged to participate in as many of the routine daily tasks as possible. The cost, at $8,500 a month, is prohibitive to many, but can be less than some assisted-living arrangements.

“If we are talking about Alzheimer’s care in assisted living, the average cost is between $6,000 and $10,000 a month,’’ said Paul Raia, the vice president of patient care for the Alzheimer’s Association of Massachusetts and New Hampshire. “And usually when you run out of money, you are out,” he said.

The Green House model has been widely used nationally for aging and other medical issues, and is tailored to find ways to offset loneliness, boredom, and hopelessness, according to the philosophy of its founder, Bill Thomas, an international authority on geriatric care from upstate New York. The holistic approach is aimed at reinventing traditional nursing home care, and creating close-knit groups of patients and those who care for them.

The state’s first Green House Project was at the Leonard Florence Center for Living in Chelsea, and scores of others have popped up all over the country since 2009, when Thomas received a $10 million grant from the Robert Wood Johnson Foundation to kick off the concept.

Facilities like the one at Fox Hill in Westwood are beginning to emerge even as the number of people being diagnosed with dementia and memory illnesses nationwide is booming, officials said.

There are 5.3 million people in the United Stated with Alzheimer’s, Raia said, a number that is expected to double over the next 15 years. More than 120,000 people with the disease live in Massachusetts, he said.

“The Green House movement is saying we can create a place where people can live in relation with other people like they would with family at home and still receive the services they need,’’ said Margaret P. Calkins, founder of Innovative Designs in Environments for an Aging Society, which provides consultation for long-term care. “Unfortunately, the way we fund senior care these days means a lot of people are in nursing homes instead of assisted living because Medicaid won’t fund it without a waiver.”

“Is it the single best solution? Not necessarily,’’ Calkins said of the Green House concept. But she added, “I hope it becomes the wave of the future.”

Raia is also a fan of the Green House concept, and worked with Fox Hill administrators on the cottage plan. He said he was glad when they accepted his suggestion to hire an employee specifically to plan activities for residents.

“Folks are very intelligent there,’’ he said. “They won’t be content with bingo.”

Instead, the activities coordinator at White Oak works on computer and thought-based therapies and activities that offer “meaningful, purposeful engagement,” Raia said, noting that it is important to maintain cognitive abilities “as long as possible.”

But what’s really important is that staff and residents maintain an emotional relationship, he said, and in the cottage environment, it thrives.