Short answer: yes, urban outdoor furniture can work in a sunroom, but I would not assume it is automatically safe or low-off-gassing just because it is sold for outdoor use. “Outdoor” usually means it can handle sun, rain, and temperature swings—not that its finishes, adhesives, foam, or fabrics are low-VOC. In a sunroom, the bigger issue is heat and trapped air. On a warm day, a sunroom can get much hotter than a living room, and that warmth can speed up off-gassing from coatings, synthetic rattan, vinyl, cushion foam, glues, and sealants.
If you want to use outdoor pieces indoors, start with the materials. Powder-coated aluminum and stainless steel are generally straightforward because the metal itself is not the main VOC source; the powder coating is usually more stable than solvent-based paint, though you should still ask about the finish. Solid wood can be a good choice if it is unfinished or sealed with a low-VOC, water-based product. I would be cautious with pressure-treated wood, unknown stains, oil-based sealants, PVC/vinyl, and cheap synthetic wicker in a closed, hot sunroom, especially if it has a strong plasticky or chemical smell. Cushions matter too: look for CertiPUR-US foam, OEKO-TEX textiles, removable covers, and fewer stain- or water-repellent treatments. No material is truly zero-emission, so “harmless” is not a guarantee.
The practical test is smell, heat, and ventilation. Before bringing a piece in, let it air out in a garage, covered porch, or outdoors for several days or weeks. Then place it in the sunroom with windows open and a fan running. If the room smells sharp, gives you headaches, or irritates your eyes or throat, remove it. A small air-quality monitor can help you track VOCs, but it is not a substitute for ventilation. In a sunroom, use exhaust fans, open windows when possible, and avoid sealing the room up during hot weather. If the furniture has a strong odor that lingers after weeks of airing, I would not keep it in an enclosed space. For sensitive people, children, or anyone with asthma, be extra conservative.
So my answer is: yes, urban outdoor furniture can be used in a sunroom, but choose low-VOC materials, ask for certifications and finish details, air it out first, and keep the sunroom ventilated. Do not rely on the “outdoor” label alone. Treat off-gassing as something to manage for better indoor air quality, not a box that is automatically checked.