After serving for more than 80 years as a place of respite and a spiritual hub, the Cenacle Retreat House in Lake Ronkonkoma is set to come down. The house, which sits at the center of the 45-acre Ronkonkoma Cenacle retreat center, will be replaced by a new, energy-efficient facility, said an attorney for the Sisters of the Cenacle, the Catholic order that runs the center. The current retreat house, a castle-like four-story building with a tower and red roof tiling, has aged to the point where it is too expensive for the sisters to maintain, said attorney David Sloan. The 86,000-square-foot building's energy and utility bills total more than $500,000 a year, he said, but the new facility will be half that size, with bills anticipated to be less than $150,000. The building also falls short of modern handicapped accessibility codes - a problem for a facility that houses about 25 retired and semiretired nuns. "We'd like to stay on Long Island, but we can't [remain in the building] with the financial problems we are facing," said Sister Mary Jane Laffan, the center's superior. The Sisters of the Cenacle declined to speculate on the cost of the new building or when it would be completed. Sloan said the facility will cost "many millions of dollars." Brookhaven Town officials last month approved a zoning law change necessary for the nuns to build a new retreat house. The next step is for the sisters to request town site plan approval, Sloan said. When the Cenacle house does come down, its closure will mark the end of a facility that has been a fixture in the area since 1927, Sister Mary Jane said. The house is on a verdant piece of land that was given to the sisters by stage actress Maude Adams, who played Peter Pan on Broadway in the early 1900s. Adams is buried at the site, which is largely obscured from view in a forested area between Smith and Portion roads. The site is part of a network of retreat centers the Cenacle sisters operate in cities from Vancouver, Canada, to Gainesville, Fla. The Lake Ronkonkoma center offers such spiritual programs as "Listening for God in Recent Films" to "Unlocking the Wisdom of the Body," also known as "The Surprising Transformation of the Couch Potato." Among the Cenacle's events this summer is a seven-hour program Aug. 1 about how to create your own altar. Attendants are advised to bring a bag lunch, the order's Web site, cenaclesisters.org, states. The Cenacle sisters, who are members of an order founded in France in the 1820s, see a modern facility as an alternative to leaving Long Island, Sloan said. The high cost of running the center, which is supported by donations, has made remaining on the Island difficult Cenacle officials have said. The cost of heating oil alone can exceed $40,000 a month in the winter, said Sloan. "They were contemplating leaving the Island but have decided to stay," he said, adding that the rest of the property will not be developed. The new building will face a battery of approvals from town and state regulators, said Sister Mary Jane, who added she hopes the process moves expeditiously. "The Cenacle has been in the community for 80 years. We've never caused a problem that I know of," she said.