A rather invisible solution to leaky old windows

From the outside, the Winsulator windows cannot really be seen behind the historic ones on this home at 50 Hasell St.

There are worse things you can do to a historic building than adding storm windows.

They often look a bit awkward from the street, but at least they can be removed. And for those who can’t afford highly skilled repair work, storm windows offer thermal and sound insulation that can make older buildings more livable and economical.

But for historic properties, there’s also something better than exterior storm windows — interior storm windows.

A Florida entrepreneur invented a type of these, patented and marketed as “The Winsulator” since 1993, that has quietly made inroads in Charleston’s historic district. Some preservationists consider them a superior solution.

Ed VerVane and his crew have been installing them recently at 50 Hasell St., an 1846 home built that has long served as the rectory for the St. Johannes Lutheran Church next door.

As they were installed, you couldn’t tell from the street which windows had them and which did not.

VerVane moved to south Florida around 1990 and developed the windows, not with historic preservation in mind but to address the energy leakage of so many jalousie and other substandard windows he found there.

“These windows weren’t efficient at all, and as you’re walking down the sidewalk, you can feel the air blowing from these windows from the sidewalk,” he says. “I said, ‘You’ve got to be kidding me.’”

He developed the technology in part at the Kennedy Space Center, whose engineers often help small businesses during their down time.

The Winsulator essentially is an acrylic pane installed inside a window leaving air space between the historic glass pane and the acrylic sheet.

The product isn’t cheap. It will cost about $300 to install one inside a large historic window. But there’s relatively little involved. A bar is installed where the sashes meet, and there are magnetic gaskets that hold the windows in place. Once that system is installed, the window panels themselves are easy to remove and replace.

Kristopher King of the Preservation Society of Charleston is familiar with the windows and says one advantage is they are gentler on historic windows than exterior storm windows, which can trap heat on the outside of the historic window.

Since the historic windows are leakier, having the Winsulators on the inside allow the heat to escape back outside.

He says it not only helps the environment but also helps the property owner save energy and experience a greater sense of quietude. “And it’s not damaging the look of the beautiful, historic buildings.”

VerVane, 68, estimates his small Sarasota-based business has worked on about two dozen historic Charleston properties, including City Hall, the Planters Inn and the Dock Street Theatre. And it has done installations on nonhistoric buildings.

“I believe we should be in all of them,” he says, “but it’s not that easy.”

Reach Robert Behre at 937-5771.