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OLIVIA IN OHIO ASKS:
The casement windows in my home are more than 30 years old. They’re showing the wear of their age and given the fluctuations in our electricity bills, they are clearly not energy efficient windows. But there are so many options out there! What’s the best window for my family’s health, for my wallet, and for the planet?
Tell Congress: Protect Families From the Plastics and Petrochemical Industry
MOM DETECTIVE ANSWERS:
Windows make me dizzy, Olivia. When we moved into an old house over a decade ago, we were forced to replace a bunch. The (gorgeous) original windows were a mess of peeling lead paint, and we had an infant and a seven-year-old. Our replacements were urgently needed to protect their growing brains from lead exposure, frequently an issue with old windows in pre-1978 homes, but every window salesperson pointed out how much we would save in energy costs. They usually said this as they handed us an astronomical project bid.
I found the process overwhelming. Anxious about lead, a neurotoxicant, I had to also quickly get up to speed on materials (vinyl vs. fiberglass vs. wood), panes (single, double, triple plus the gas in between panes), glass glazes, and decorative and technical lingo I had no idea existed: pockets, grids, sashes, mullions, muntins, aprons, casings… Bone-tired, up all night nursing my baby, I wanted to give up. Motivated by lead, eventually we figured it out. Today, I never think about my (nice!) windows. There’s a lot to consider, but you too will get some. Here’s how.
Why replace windows?
The two biggest reasons to replace old windows are lead and energy efficiency. If you have lead in your home, be sure to mention it to the window installers. Not everyone is certified to safely remove and remediate lead. Most of the bigger window companies or the contractors they work with are and can appropriately handle lead—for a minimal added fee per window.
As for energy, investing in energy efficient windows helps reduce consumption for heating and cooling, and lowers utility bills, according to Leadership in Energy and Environmental Design (LEED), a green building rating system created by the U.S. Green Building Council (USGBC) to promote sustainable building practices. Windows actually play a critical role in achieving LEED certification. New windows can also prevent air leakage, improve indoor air quality, and according to the Department of Energy, reduce lighting costs.
Best window materials for you and the planet
To achieve LEED certification, the quality of windows, not just their energy performance, is a top consideration. But when it comes to what window materials are safest for humans and the planet, there’s woefully little research. Most window reports are focused on energy efficiency. Energy Star has long certified windows, which could be helpful, but the Trump administration is currently considering ending or privatizing this useful consumer-friendly program. The basic options—ranging loosely from least to most expensive—are vinyl, aluminum, wood, and fiberglass. Some say fiberglass is the most durable, but most window resources are written by window companies, so take that into account.
No to vinyl: I avoid vinyl, which is made from the toxic petrochemical vinyl chloride, a known human carcinogen that causes liver cancer as well as leukemia, lymphoma, brain cancer, and lung cancer, in all areas of my life. I didn’t want it for windows that I hope to have for as long as yours have lasted.
A slow yes to wood: I failed to find studies on environmental and health impacts of other window materials and if they off-gas into indoor air. I know aluminum mining is environmentally destructive and learned it’s possibly not as energy efficient as other window materials, so I crossed it off my list. I similarly found little to no research on impacts of cured fiberglass window frames on health (as opposed to fiberglass in general). I was compelled by wood, though some sources claim it’s not as durable as fiberglass, it can warp, rot, and also it’s sometimes treated with fungicides, pesticides, and insecticides.
Ultimately, we went with wood windows from a reputable company—and had them installed by the company too. I asked a lot of questions and liked their answers on materials, wood sourcing, their lead remediation protocol, and their financing options (more on that below).
Got cash? Go custom. This was not within my budget, but custom windows would put you in control of materials sourcing, including installation materials.
Whatever material you choose, don’t forget to ask what the installers plan to do with your old windows. Hopefully they have a reuse or reliable recycling program.
Glass choices
Even after you’ve chosen a window material, there are more choices to make! When it comes to sustainability, window glazing is key. Low-E (low emissivity) glass coatings reflect heat while allowing natural light to enter. LEED says Low-E improves insulation and reduces heat.
Next up, it’s time to consider panes. Multiple (instead of single) panes of glass filled with gas like argon or krypton in between provide additional insulation. I haven’t found any damning research on these gases and indoor air quality in the very unlikely event a window breaks or leaks. Choosing double or triple panes mostly has to do with the weather where you live, so that’s something to discuss with your window salespeople.
Heads up: I have recently seen other window coatings for sale, including antimicrobial ones. I avoid antimicrobial chemicals in soap, hand sanitizers, and even garbage bags. The Green Science Policy Institute says some antimicrobials may disrupt hormone function, and some are associated with developmental and reproductive effects, allergen sensitivity, and antibiotic resistance. They usually provide zero benefit to consumers despite this potential health harm so I would also avoid them on windows. Keep an eye out for other glazes that sound too good to be true when shopping for energy efficient windows, and always ask questions.
Affording new energy efficient windows
While not a health concern, you asked about wallet-friendly windows. According to This Old House’s 2025 windows survey, the cost of a replacement window ranges from $400–$900 per unit with an average price of $554. Homeowners typically purchase four windows, with total project costs averaging $8,803, including installation. My project was, unfortunately, a lot bigger than four windows. I was relieved to discover that some window companies offer financing and years to pay off the fee before owing interest.
If you don’t have almost $9,000 lying around for windows, you’re not alone. To lower the price, look for funding, rebates, and incentives for energy efficient upgrades. A good place to start is with an energy audit. New York, where I live, offers these for free. Currently there is a $150 tax credit for energy audits through December 31 plus a 30% tax credit for insulation, sealing leaks, and replacing leaky windows. (Learn about other energy efficiency upgrades you can make before clean energy tax credits disappear.)
Meanwhile, there are steps everyone, including renters, can take at home to improve energy efficiency of existing windows without replacing them, like adding weather stripping, fixing old caulking, installing storm windows, and even just using window coverings and shades.
I hope this helps!
Tell Congress: Protect Families From the Plastics and Petrochemical Industry