Our previous articles discussed window and glass efficiencies, warranties, and the top reasons to replace windows. This article will expand upon these topics and begin to cover some of the window coverings which will be able to reduce energy usage associated with heating and cooling, and make your home more comfortable year round.
Most types of window treatments will result in energy savings, but the exact savings will depend on the type of attachment, the season, the climate, and how the attachment is used.
In addition to the window treatments discussed below, storm windows with low-e coatings are effective at improving thermal performance of windows and reducing solar heat gain.
Operable Window Coverings
Operable window coverings are by far the most popular choice in window treatments because they offer the flexibility to choose from having the window coverings open or closed. This allows the homeowner to decide their level of privacy, maximize natural light, and to take advantage of solar heat benefits.
Most common operable window coverings: shades, blinds, curtains, drapes, shutters
Interior Window Treatments
Window treatments come in a variety of different form and shape factors. This is primarily due to personalization – a great deal of personal touch can be applied when choosing these treatments.
Insulated Cellular Shades
Cellular shades are very common, but most people know them by how they look.
Insulated cellular shades are made of a pleated material designed to fold up like an accordion when they are fully open at the top of the window. These are beneficial when closed because the air inside the curtains acts as an insulation layer which can reduce heating costs in the winter.
Insulated cellular shades typically offer the highest level of comfort, privacy, and energy efficiency measured by R-value
Some cellular shades include the option of automation, allowing the blinds to open and close on a set schedule. The schedule can be seasonally optimized to reduce heating and cooling loads while maximizing natural light and home comfort.
Window quilts have a sheet of quilted or knit material that can be opened by rolling and closed by unrolling. They typically fit snug against the trim, either on tracks, with velcro, or another mechanical attachment at the top of the window frame.
Their tight fit offers R-value increases similar to cellular shades, and they typically cost less.
Window blinds—vertical or horizontal slat-type—are more effective at reducing summer heat gain than winter heat loss.
Because of the numerous openings between the slats of blinds, it’s difficult to control heat loss through interior window blinds, but the slats offer flexibility in the summer. Unlike shades, you can adjust the slats to control glare, light, and solar heat gain.
When completely closed and lowered on a sunny window, highly reflective blinds can reduce heat gain. Horizontal slat-type blinds can also be adjusted to block and reflect direct sunlight onto a light-colored ceiling. A light-colored ceiling will diffuse the light without much heat or glare, while allowing you to take additional advantage of natural daylighting.
Curtains and Drapes
Curtains are fabric interior attachments that are sized to fit the window, while drapes reach all the way to the floor.
A drapery’s ability to reduce heat loss and gain depends on several factors, including fabric type (closed or open weave) and color. With such a wide variety of draperies available, it’s difficult to generalize about their energy performance.
The most efficient curtain and drape combination is with a two layers. Two draperies hung together will create a tighter air space than just one drapery.