20 Ways to Make Your Home Healthier for Cozy Season, According to a Building Biology Expert

WLLW Studio founder, building biology expert and interior designer Lisa Sternfeld has a very personal connection to her work. She developed her specialty through completely overhauling her own home to support her son through severe respiratory challenges. She now combines what she’s learned about everything from non-toxic materials to advanced air purification and acoustic dampening with her design training to create spaces that look and feel wonderful, in every sense of the word. As you transition your home for cozy season, we’re sharing science-backed ways to make it even more comfortable — with examples from Lisa’s own home.

Lisa used BEECK Mineral Paint (which is made from natural raw materials and emits either very low or zero VOCs) extensively through her home, in both custom-blended and readily-available colors. “Mineral paint has been around for generations, but there’s renewed interest in it as more of us pay attention to what our building materials are made of,” she says.

Interior decorators and scientists agree that it’s well worth your while to develop a visual banquet in your home. “Research in neuroaesthetics, the study of how our brains respond to beauty and design, helps explain why layered spaces can feel so good to us,” Lisa says. “Our senses like something to engage with, but we also want a space to feel comfortable and calm. Texture, material, light, color and objects with personal meaning can create that balance, along with a sense of familiarity and connection.”

This one’s tough to hear: Though the warmth and atmosphere of candlelight is especially satisfying in the fall and winter, burning anything indoors exposes us to harmful combustion byproducts, whether it’s loaded with scent or not.

“If you want to light [a candle] occasionally, I would keep it as simple as possible. I look for an unscented candle with a short, transparent ingredient list,” Lisa says. Greentree Home, for example, makes beautiful candles from 100 percent North American beeswax with cotton wicks and no added fragrance.”

Lighting a candle for a period of time rather than all evening can make a difference as well, as does keeping the number of candles you’re burning to a minimum and making sure your home is well-ventilated.

As hours of natural light dwindle, how we experience artificial light becomes especially important. “A bright ceiling fixture can create glare and a very different sensory experience from light coming from a lamp or sconce closer to eye level,” Lisa says. “In the evening, I prefer lower, softer layers of light from table lamps, floor lamps and sconces. They create a warmer, cozier feeling as we move toward night.”

As Lisa selected materials for her home, she looked to improve indoor air quality by getting rid of sofa and chair cushions made with chemical-heavy, polyurethane foam and replacing them with fillers made of natural latex and down. She swapped out her synthetic, polyester-blend rug for a vintage wool Turkish Oushak colored with vegetable dyes.

Who says leaf-peeping needs to be an outdoor activity? “In fall and winter, I’m drawn to plants with deeper foliage that bring richness and color into a room,” Lisa says. “I have a tall Abidjan rubber tree with dark green leaves and deep red undersides that feels especially lush this time of year. I also love dark-leaved calatheas for their color and pattern.”

The flora in your home is as vulnerable to environmental changes as you are, of course. “The plant on our coffee table is a maidenhair fern, one of my favorites, and it always keeps me humble,” Lisa explains. “It’s a finicky plant, but I keep trying!”

Ferns’ delicate, eye-pleasing leaf shapes and textures leave them especially vulnerable to changes in humidity. “Once the heat comes on, I’m much more mindful of where I place my plants,” Lisa continues. “Indoor air can get very dry, particularly near radiators, vents and other heat sources, and ferns can be especially sensitive to that.” (Lisa’s home updates to address her son’s sensitivities included both the installation of a humidity-control system and a medical-grade air purifier.)

If your indoor space lacks the conditions to keep potted greenery alive through the colder months, don’t despair; you can still enjoy biophilic benefits by bringing in fresh-cut blooms and branches.

“From a health perspective, plants are one of the simplest ways to support our connection to nature, something often described through the idea of biophilia,” Lisa says. “That connection feels especially important when we're spending more time indoors. They bring color, texture and movement into our daily lives.”

Lisa’s home is punctuated with storied pieces like this 19th-century, marble-topped burlwood chest (a 1stDibs find), a move that both develops its character and has occasional environmental benefits.

“Many older pieces were made from straightforward materials like solid wood, natural fibers and simpler finishes,” she explains. “Depending on the piece and its condition, that can sometimes make a vintage or antique piece a healthier choice than new furniture made with composite woods, adhesives, synthetic materials or added chemical treatments. An older piece has also had years for much of its initial off-gassing to dissipate.”

Lisa’s spectacular lamp created from a piece of found driftwood, in turn, is just the sort of design detail that calls for thorough investigation prior to incorporation; objects with history can have all kinds of history. “I look carefully at the condition of anything I bring home, particularly upholstered pieces. I check for signs of moisture or mold and consider what may have been added through refinishing or reupholstery,” she says.

“Upholstery can also hold dust, so I’ll have a piece cleaned before it comes into the house if needed. I check seams, crevices and underneath for signs of pests. Painted pieces deserve a closer look, too, since older paint can contain lead.”

Lisa made a very intentional choice to leave her marble kitchen countertops unsealed. “There are lower-VOC and water-based stone sealers available, but for me it came down to a simple question: if I didn’t need to add another treatment to a surface that comes into such close contact with our food, why would I?” she recalls.

“There is a tradeoff,” she acknowledges. “Unsealed marble is more vulnerable to etching and staining, so we’re careful with acidic foods like lemon, tomatoes and vinegar, and so far we’ve been spared a red wine spill! But I also don’t want to be too precious about my home. Marble is a natural material, and part of its beauty is that it changes as we live with it.”

If you find yourself deep cleaning your space for upcoming holiday entertaining, this one's for you. While Lisa is dedicated to challenging the notion that healthy homes have to be sparse, white and minimal, she does believe that less is more when it comes to cleaning products. “The simpler, the better,” she says. “A little baking soda mixed with water makes a great paste for the right surfaces, and white vinegar is a staple in our house, though never on our marble!”

When she purchases cleaning products, “I use Koala Eco’s dish soap and their multi-purpose kitchen and bathroom cleaners, which are plant-based, work incredibly well and smell amazing,” Lisa says. “For times when I want something unscented, I use Branch Basics’ concentrate for multipurpose cleaning and their fragrance-free dishwasher tablets, which are also enzyme-based and plastic-free.”

Many a trend piece has been written about the German practice of lüften, or ‘house burping’ — that is, opening your windows once or twice a day for 5-10 minutes to cycle out stale air, cooking smells and so on. Lisa’s take on the concept?

“My German grandmother opened the doors and windows of her home every day, year-round, even in the middle of winter. She believed it was important to let fresh air in, and so do I,” she says. “There is a lot we can learn from the way people lived before our homes became so tightly sealed and mechanically controlled. We also know more today about outdoor air quality. If there’s wildfire smoke, poor air quality or a high pollen count, opening the windows can bring in exactly what you’re trying to keep out.”

The larger point is that air needs to move through a home. “On a good air-quality day, opening the windows for even a few minutes is one of the simplest ways to bring fresh air in. I pay particular attention to ventilation during and after activities that affect indoor air, like cooking and cleaning. In the kitchen, a range hood that vents to the outdoors makes a real difference,” Lisa says.

“The larger point is that air is part of the design of a home. We think carefully about everything we can see, but some of the most important qualities of a home are the ones we can’t.”

I think about color in relation to what a room is meant to support,” Lisa explains. “A living room is a gathering place, so I might introduce warmer, more enveloping colors that encourage people to settle in and stay awhile: a warm ochre, earthy terracotta, deep olive or a richer neutral.”

“As the days get shorter in fall and winter, paying attention to light throughout the day becomes even more important,” Lisa explains. “I try to bring as much natural daylight into the house as possible in the morning and through the day. Light is the strongest signal our bodies use to set our circadian rhythm, so those darker mornings can really change how we experience the season.”

If you’re looking to transition to bed linens with natural dyes, the rich color of indigo is an excellent choice (and one Lisa has deployed to great effect in her own bedroom). “Blue has always been my favorite color, and I especially love the depth you get from natural indigo. Blues and blue-greens can have a calming quality, but how we experience color is also influenced by its intensity, the light in the room and what that color means to us personally,” she explains.

While some experts suggest using a “sunrise alarm” to serve as a programmed signal that it’s time to wake up and begin the day, Lisa prefers to begin that gradual process once she’s awake. “Once I'm up, I gradually increase the light levels in the house rather than turning on bright lights immediately,” she explains. “If there's natural light available, I open the shades and let that in. If it's still dark outside, I start with dim, warm lamplight and brighten the house as the morning goes on.”

When you’re looking to transition your home to more health-supportive materials, “don’t start by throwing everything out,” Lisa warns. Think about where you spend most of your time, and begin there.

“Textiles are an easy first change,” she explains. “When sheets, towels or bedding need replacing, look for natural fibers like cotton, linen or wool and, when available, choose organic options or look for independent certifications. GOTS is a useful standard for organic textiles, while OEKO-TEX STANDARD 100 tests textiles for harmful substances.”

"From there, make changes as things naturally need replacing," Lisa advises. "When it’s time for a new sofa, rug, mattress or a fresh coat of paint, use that moment to ask a few more questions: What is this made of? What has been added to it? Is there a healthier option within my budget? A healthier home is built through many decisions. They don’t all have to happen at once."