It’s always better to replace old windows. Right?

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We slept, or tried to, in a boxcar on a rattling freight train, rumbling through the cold, dark plains. At least, that’s what it felt like some winter nights when we first moved into our 1920 two-family. When the wind blew hard off the ocean, the original windows in our bedroom would shake and clatter in an arrhythmic fury. I hid my head under the blankets like a Depression-era hobo, trying to muffle the racket and hide from the icy drafts.

For two autumns we spent entire Saturdays sealing our house’s many old windows in plastic, armed with a hair dryer and glorified Saran Wrap. It helped with the drafts, but not the thunderous shaking. So eventually, lured by the promises of tax breaks, energy savings, and a solid night’s sleep, we began installing vinyl replacement windows a handful at a time.

And I’ll be honest: They are mostly marvelous. Compared with our sticking, rattly old windows — which, with their broken ropes and weighty sashes, could easily be mistaken for makeshift guillotines — they open smoothly, shut snugly, tilt inward for easy cleaning, and keep more of our heat inside the house. Best of all, it doesn’t sound like the End Times on a windy winter night.

But I’ll be doubly honest: I’m starting to second-guess our decision.

Saving money and energy

The big selling point of replacement windows has long been the energy savings afforded by their double-paned, coated glass. Instead of just a thin piece of glass separating your living room from winter’s worst, double-paned windows have two layers with a pocket of air (a natural insulator) or a dense gas (such as argon) between them. Meanwhile, a transparent, low-emissivity coating (Low-E), is added to the glass to reflect heat. “When heat tries to escape during the winter, the Low-E coating reflects the heat back into your home — similar to how the silver lining inside a thermos reflects the temperature of the drink back into the container,” said Amber Castrataro, brand communications manager at Harvey Building Products in Waltham.

The big selling point of replacement windows has long been the energy savings afforded by their double-paned, coated glass.kuchina/Fotolia

Uncle Sam has also offered a compelling incentive to replace windows: In 2009 and 2010, homeowners could receive a onetime 30 percent tax credit of up to $1,500 toward the cost of many energy-efficient home improvements, including replacement windows. However, that tax credit has since been ratcheted down to 10 percent (with a $200 limit for windows in 2016). And in 2012, the Federal Trade Commission settled charges against five replacement-window companies, forbidding them from making false claims about projected energy savings. In fact, it turns out replacing windows is not always the energy-saving slam dunk it’s made out to be. As Consumer Reports has noted, even when installing Energy Star-rated windows, it can take decades to recoup your investment.

A 2010 study by Frank Shirley of the American Institute of Architects compared the cost and thermal performance of replacing a window in a pre-1940s Boston home with simply installing a storm window instead and found it was “far more cost effective to add a storm window to a well-maintained historical window than to replace the window with a new [inert gas] unit,” given their similar efficiency. A study by the National Trust for Historic Preservation reached a similar conclusion, determining that window-retrofit measures such as installing a storm window and weatherstripping achieved energy savings comparable with a replacement window.

Preservationists argue that windows in historic homes are meant to be restored.Alessandro Guerriero/Fotolia

And yet the idea of restoring our crummy old windows never even occurred to us. David Liberty , a retired window-restoration expert who worked in the industry for 30 years, said we, like many other homeowners, simply fell prey to the replacement-window craze.

“When I first started in the early ’80s as a handyman,” Liberty said, “everyone, myself included, assumed new windows were better.” If people couldn’t afford vinyl replacements, he would get their old rope-and-pulley windows back in working order, but he also found himself fixing fairly new vinyl windows and discovered some common problems that plagued them: failing springs and suspensions, brittle plastic parts, cloudy glass. “I realized that all replacement windows, no matter how much you pay for them, have the same temporary technology,” he said. “They offer warranties of 10 to 20 years, because that’s all you’ll get. The ones that offer lifetime guarantees are hedging that bet somewhere.”

Meanwhile, if you properly restore, weatherize, and add a good storm window to your home’s 100-year-old windows, Liberty said, “They could last another hundred years . . . So what’s a better investment, 20 years or another lifetime?”

Tommy Ingram, vice president of sales at Coastal Windows & Exteriors in Beverly, said a well-made replacement window will stand the test of time — Coastal guarantees all its vinyl products for 50 years — but it comes down to quality and materials. “If you’re buying a vinyl window, you have to make sure the entire window is pure virgin vinyl,” he said. Many companies use recycled vinyl, he said, which seems and sounds eco-friendly, but the blend of new and old plastic can lead to problems with the bonding. “It’ll turn yellow, become brittle . . . It may be a green choice in the short term, but that window’s going to need to be replaced in 15 years, especially if it’s facing the sun.”

Remodeling Magazine estimates the cost of installing 10 upscale vinyl replacement windows at $14,725 — almost $1,500 per window — but restoration isn’t necessarily a less expensive option. Liberty said full restoration of a double-hung window — adding weatherstripping, replacing the chain, stripping and rebuilding the sashes, and installing a new Harvey Tru-Channel storm window — costs between $1,000 and $1,500. “Stripping is the most expensive part; it’s extremely labor intensive,” he said, particularly if there’s lead paint involved. If the paint and glazing are in decent shape, a basic mechanical restoration costs about $350, Liberty said, and a new storm window averages $300 installed.

If those prices hit you like a blast of cold air, consider that restoring old windows is a fairly straightforward, if tedious, DIY project, according to Deb Beatty Mel, assistant director at the Boston Building Resources Reuse Center, which offers homeowner workshops on basic window repairs.

“These windows, they’re built to be restored. They can be repaired by a handy homeowner,” said Beatty Mel, who has restored about half of the windows in her home. “You can take it in bites. It’s definitely a labor of love — it takes a long time — but the more you do it, the less intimidating it is.”

Beatty Mel said restoring windows makes sense from a sustainability standpoint as well. “You’re extending the useful life of a material,” she said, instead of tossing it in a landfill. “They were custom made to go with your house from the beginning, so aesthetically and architecturally they’ll match your house.”

Still, not every home’s original windows are a prize to be restored; they haven’t “made ’em like they used to” since about the 1970s, when softer farmed wood began to replace old-growth timber in windows. “If you have a historic home, like a Victorian for example, you may want to go down the refurbishing route,” said Chris Chu, a West Newton architect and the Globe’s Ask the Architect writer. “If you have a standard-issue 1940s or 1950s Colonial or ranch, maybe replacement windows will suffice.”

Late 20th-century houses are good candidates for window replacement, said Stephanie Vanderbilt, owner of Coastal Windows & Exteriors. “Around 75 percent of our work is on post-1960 homes,” she said. And even Liberty conceded that vinyl replacement windows make sense in basements and bathrooms. “No wood window will stand up to that kind of constant moisture,” he said.

What to look for

If you decide to replace your windows, you’ll have a lot of choices to make: double-hung or casement; vinyl, wood, or other materials; and myriad manufacturers and installers, not to mention design details.

Castrataro recommended seeing the windows in person before buying them. “People usually look through a window rather than at it,” she said. “However, without really looking at the construction or physical appearance of a window, you might find you’ve chosen one that uses an inferior-quality vinyl, has a bulky frame, messy welds, doesn’t open and close easily and securely, or has unsightly hardware — things that are difficult to see on a brochure or website.”

Ingram says finding a company that stands behind its products is the most important consideration when window shopping. “You can buy the most efficient window in the world, and if they don’t install it correctly, you may as well just keep what you have,” he said, adding that consumers should check the fine print of the warranty. “The more fine print, the worse it is.”

If you choose wood windows, remember that most modern wood is farmed quickly and isn’t as rot-resistant as the old-growth wood used a century ago. That means you might want some type of cladding, either an aluminum or vinyl covering, to protect the exterior wood from the elements if you’re not keen on painting it every few years.

For consumers comparing energy-efficiency labels on replacement windows, low U-factor and air-infiltration scores are of particular importance in the cold Northeast, where winter heat loss is a bigger issue than keeping out the heat in summer. “The lower the U-factor, the better the insulating power,” Castrataro said.

When choosing your windows and an installer, Ingram said, don’t risk harming your home’s value by cutting corners. “If you’re looking at anyone selling for less than $600 a window, it’s typically not something you want in your home,” he said.

Meanwhile good-quality new windows can boost a home’s resale value — and, Vanderbilt said, they can improve your quality of life, too.

And that’s true. Our freight train of a house is, without a doubt, far quieter and more comfortable since we replaced the windows. I just don’t know whether I’m comfortable with the idea that we chucked all those old, irreplaceable windows into a dumpster — without at least considering the alternative.