Q: I recently built a sunroom on the south side of my house and used Low-E glass because it keeps out most of the heat from the sun. I didn’t think about it at the time but will it also keep plants from growing?
A: According to Dennis Creech from Southface Energy Institute, Low-Emissivity glass inhibits the transmission of infrared and ultraviolet solar energy. It keeps heat from coming indoors in summer and prevents heat from leaving through your windows in winter.
Low-E glass is coated with a microscopically thin layer of metal. You can barely perceive any difference between regular glass and Low-E glass. Even so, Low-E glass does inhibit some of the visible light a plant could use. Most Low-E window products rate their visible light transmittance between 75% and 85%. All in all, your indoor plants will probably show no ill effects if you care for them properly.