Insulated shades and blinds can be installed on window interiors to increase insulation and provide glare control. Products without side tracks typically add R-1 to R-2 to a window’s performance, while products with side tracks may add as much as R-4. Most common are insulated cellular shades that expand when deployed, but can draw up, accordion-like (usually at the top of the window, though some offer bottom-up and top-down deployment). Some of these products contain multiple layers and produce a honeycomb-like cross-section when lowered. The shades are made to fit fairly tightly in the window jambs to limit airflow around them (and reduce convective heat transfer). Metalized Mylar film in the cellular structure insulates much like reflective bubble-pack.
Quilted window blinds roll up or fold into pleats like an accordion (and are usually hidden in a valance). They can be lowered at night to provide insulation or used during the day to block unwanted sunlight. Fill sewn into the quilted fabric provides insulation. A layer of reflective Mylar in the fabric helps keep heat in the room. The blinds’ edges fit into tracks to stop most air leakage.
Insulated cellular shades and quilted blinds only save energy and improve a home’s thermal comfort when they are used—and they have to be operated manually. To realize that benefit in the winter, for example, they have to be lowered at night and raised during the day.
Alex Wilson is the founder of BuildingGreen, the Brattleboro, Vermont-based publisher ofEnvironmental Building News, GreenSpec, and LEEDuser.com. He is also president of the Resilient Design Institute.
Window coverings & attachments • efficientwindowcoverings.org