The commercial market, functional considerations, and aesthetic basis for your home’s windows can all be totally overwhelming. The countless number of choices available to buyers is a double-edged sword with unlimited capability to customize your selection, but a potential pitfall in making decisions relative to one another. To help you navigate this realm, we’ve compiled this guide to understand what’s what and what should matter to you in choosing windows for your home.

Anatomy

A brief vocabulary lesson is worthwhile to help orient you within the technical terms used in window production. Every window has four conventional parts: jamb, sill, head, and sash. Think of the former three terms as the edges, or frame, that hold the main part of the overall assembly (the sash) in place and provide the mechanisms for operating the window. Sashes can be further sub-divided into their own individual elements, including: stiles, rails, muntins (or mullions), and lites. These each describe the pieces of the assembly that hold and separate the glass.

Operation

Windows are typically classified by how they open and close, each serving a specific function relative to their location and size. When you’re digesting the diagrams below, note that the dotted “arrow” over the window indicates the location of the hinge or direction it moves. Here’s a summary of the conventional types used in most homes:

Double-hung and single-hung

These are the most common models used in residential construction. They contain two individual sashes “hung” in the frame. The double and single labels refer to the number of sashes that are operable. For example, both sashes in a double-hung window can be slid up and down. For this reason, the screen is located on the outside face of the assembly to allow the sashes to move independently.

These are best suited for traditional styles of architecture. Their historical association and complexity of individual pieces in the assembly tend to exude a more formal appearance. Different patterns of muntins and lites also contribute to the character of the home. As a basic rule of convention – the more divisions there are in the glass, the more traditional the window will look. These patterns are often given a label relative to the number of lites/muntins they have. The window above can be called a “6 over 6” because there are six individual “cells” in each sash.

Casement

Casement windows have a single sash attached to the frame on side. They have a vertical hinge (or set of hinges) that allows the window to swing open just like a door. The screen is located on the inside face of the assembly to enable this movement.

These can employed to convey both a traditional and contemporary aesthetic on a home. The same rule regarding the muntin pattern on individual windows applies with these as well, but you will find that they tend to be grouped in multiples of two or three to create larger spans of uninterrupted glass. This treatment errs on the more contemporary end of the spectrum. The crank hardware will be a distinctive element of the window, so be sure to consider the style and finish relative to the look you desire.

Sliding

Sliding windows are the horizontal counterparts to double- and single-hung assemblies. With operable tracks on the head and sill, the sashes can move side-to-side within the frame. These are best suited for narrow height clearances such as basements and high-mounted locations like bathrooms.

Awning and hopper

You can think of awning and hopper windows as the horizontal equivalents of casement windows. These also open in a single direction and have a hinge on the top or bottom of the frame. Awnings are top-hinged, making them an ideal application for rainy locations where you can block out falling water from above while still facilitating ventilation. Hoppers tend to be used most in contemporary applications as the bottom sash of a larger assembly – this allows fresh air from the outside to gently travel up and into the space.

Fixed (inoperable)

Also called picture windows, these do not open or close and are used primarily to maximize the amount of light and view for a space. For this reason, they are typically manufactured in the largest dimensions of the conventional window types.

Performance

Windows serve the primary function of bringing light and air into a home. As penetrations in the shell of the building, they also make it susceptible to the unwelcomed gain and loss of heat. This affects both your level of comfort and the operational costs to maintain that comfort. For these reasons, it is worthwhile to understand how windows derive their efficiency.

There are two measures to consider when determining the energy performance of a window: thermal insulation and visual transmittance. As a rule of thumb, more panes (number of layers of glass) provide more insulation and more efficiency. The small gaps of air between panes allow for a tighter seal, keeping the heat where you want it relative to your specific climate and comfort preferences. The transmittance is a factor of how much heat is allowed to penetrate the glass due to the intensity of light shining through it. Modern coatings applied to or manufactured within the glass can provide the ideal balance between maximum brightness and minimum heat transfer.

Do you have questions about making the right window choice? If so, leave us a comment to get tips specific to your home!

Guest blog courtesy of W.C. Ralston Architects, an architecture and planning firm that has built an enduring reputation for design excellence in homes, neighborhoods and communities across the Mid-Atlantic region. Learn more at www.wcralston.com.