I work in the building supply industry, albeit up north at the opposite side of our country, and nobody puts in windows with "clear" glass anymore, no more than anyone uses single panes of glass these days. Since 1983, windows have been manufactured with insulated glass units that are designed to to save on energy costs of both heating and cooling, and to reduce UV damage to home interiors. I doubt many people on these forums who grow in natural light have plants getting the full spectrum of sunlight through their windows - unless they live in a an old home with the original windows, pre-1980's. Low-E glass is fine for houseplants. Here is an article I found on the web (and there are many) dealing with the subject of modern windows and house plants and explains it quite nicely: does-low-e-glass-affect-houseplants

That said, perhaps you are talking about an aftermarket additional film or tint applied to the inside of the glass? In that case, only the manufacturer of your particular product could tell you how much of the solar spectrum it removes. If you think it is cutting out more than you want for your plants, why not add a small source of artificial light and see if it makes the difference you are looking for?

I agree with Anne. When we got our replacement windows we went from old farmhouse CLEAR windows to Low E glass windows. I was not happy. I wanted CLEAR and dug my heels in the sand. But it was explained to me that doesn't exist anymore. Sooo, Low E it is. If you rely on windows for your plants as I do, supplemental light may be in order. Even a lamp will help. Rosie