Warren, Vt. — Dotty Kyle and Eric Brattstrom had an ambitious vision for the home they would build when they sold their bed-and-breakfast here seven years ago and retired.

They were environmental and community advocates, so they wanted it to be as sustainable as possible — ideally net-zero, producing as much energy as it used. And because they would be living on a modest fixed income, they needed to make sure it was inexpensive to maintain.

But they didn’t want to scrimp on luxury or size, so against their architect’s advice they insisted on 5,000 square feet, enough space to accommodate all their children and grandchildren at the same time. And a $30,000 hydraulic elevator, so they could age in place. And a separate apartment for the inevitable time when extra help was needed.

The indoor pool was just for fun.

“We sold a nine-bedroom B&B and then pretty much recreated it right up the street,” said Ms. Kyle, who is now 78, shaking her head with the kind of clarity only hindsight affords.