Casement Windows: Are They Energy Efficient?

Casement Windows

Keep Your Home Energy Efficient with Casement Windows from Revival Sash

Casement Windows: Are They Energy Efficient?

When you look at the many window choices that exist in today’s world– fixed, picture, double hung, awning, and more –casement windows are the ones you’ll find in some of the world’s most admired architecture. An often preferred choice of architects, in both modern and traditional styles, casements are descendants of French doors and centuries-old European buildings. Elegantly proportioned, they’re also more satisfying to use. Flung wide open, they bring the outside in like no other window can do.

This was more than enough for designers and owners, until energy efficiency suddenly arrived.  Today, designing a building is more than sweetness and light. Being energy-efficient is a common design goal, and windows are no exception. So, in this new order of design, does the casement window still reign?

Happily, for architects and owners alike, the answer is yes.

Data shows that windows of all kinds, in both residential and commercial buildings, are major players in global energy consumption. A typical house can lose 30% of its heat or air-conditioning energy through its windows alone. That’s more heat loss and gain per square foot than occurs in roofs or walls. And, as windows are often 15 to 20 percent of wall areas, that adds up to a lot of wasted energy and money.

How does that energy leave the building? It mostly leaves through the windows as air leakage, easily felt in older windows, but present even in modern ones. Efficient windows block this air with weather-stripping and solid closing devices. But only hinged casement windows (or their close cousins, awning or hopper windows) are able to press their moveable sash tightly up against both the window frame and its surrounding weather-stripping. This reduces air leaks to essentially zero. Double-hung windows are not inefficient, but the way their parts slide instead of hinge, gives them a measurably greater amount of air leakage than casement windows. This means, according to, casement windows are the most efficient operating window you can buy.

We mostly think about how well a window closes, when we think about energy efficiency, but during hot months or in warm climates, how a window opens can dramatically reduce energy use. Because the casement window opens more fully than any other type, its ventilation capabilities are easily the highest. In many climates, the air is too warm to rely solely on natural ventilation, but by using opening windows along with using air-conditioning at different times – called “mixed mode ventilation” – can result in energy savings of up to 47% in a building.

Along with this unique closure characteristic that stops air leakage, casement windows easily accommodate other energy efficient features. Many of these are optional, so when purchasing casements, pay close attention to them and how they might affect your view, comfort, and cost.

A few of these additional choices you’ll have are:

  • Low-e glass: Efficient and economical, this microscopically thin layer of metal coating reflects sunlight, dramatically reducing solar heat gain in summer. Fortunately, it performs in reverse as well, keeping heat inside the building in colder months. As a bonus, it reflects the sun’s UV rays that play havoc with artwork and furnishings.
  • Argon or krypton gas infill: These non-toxic gases fill the space between panes of double-glazed casement windows. Less conductive than air (they’re denser), both are powerful insulators, and when combined with low-e glass, double the energy efficiency of clear class with negligible extra cost.
  • Triple pane or laminate glass: These higher insulating glass options may or may not be worth the extra money, depending on your climate and desired comfort level next to the windows.
  • Warm edge spacers: These are the little blocks holding the panes of double-glass apart. Formerly aluminum, now you want “warm” spacers made of thin stainless steel, plastic, foam, or rubber. These are less conductive to heat and will prevent condensation around the glass edges.

So the answer to our title question is a resounding yes. In fact, casement windows are absolutely the most energy efficient windows available.  Experience them yourself in our Manhattan showroom at 135 East 57th St 15-121, or browse our website.

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