Windows are an important investment in your home’s curb appeal and your quality of life. They’re also pricey, often costing hundreds or even thousands of dollars to install or replace. Gone are the days when homeowners’ interest in windows was limited to size and shape: today’s energy-conscious consumers want to minimize costs of heating/ cooling their homes. Whether you’re building a new home or planning to replace existing, the key is knowing which choices will give you the biggest bang for your buck without impacting your bottom line. This guide is intended to help you make informed choices as to best window options for your home.

Factors to Consider When Choosing Windows
You can’t choose the right windows for your home without first understanding important factors like designs, sizes, framing, and energy-efficient components. These characteristics make all the difference regarding the visual appeal, functionality, and money-saving benefits good windows can provide. We’ll review these considerations in more detail to help you make the right choice.

Types of Windows
To begin, one needs to become familiar with the most common types of windows for residential spaces. Each option has benefits and drawbacks, largely depending on where you plan to install them. As you read, consider which window style best fits the spaces throughout your home.

Single-hung Windows
A single-hung window is a traditional style that opens vertically when pushed. Single-hung windows have a fixed upper sash – the portion of the window surrounding the glass pane – and a movable bottom sash. The bottom sash is the part of the window the homeowner will push upward to allow air to flow in. Single-hung windows are most common in historic and craftsman-style homes. Their limited functionality has made them a less popular choice than double-hung windows.

Double-hung Windows
A double-hung window is similar to a single-hung in that the sashes move to open the window. The difference is that neither of the double-hung window’s sashes is fixed; the bottom moves up, and the top moves down to open the window. If opened simultaneously, the two sashes will overlap in the middle to allow airflow through the top and bottom sections of the window. Double-hung windows have a traditional, versatile style, making them incredibly common in modern homes. Many homeowners opt for double-hung over single-hung windows because of the two operating sashes that allow for greater ventilation and easier cleaning.

Arched Windows
Arched windows are the most common specialty window shape people choose for their homes. They have a square or rectangular bottom half and a rounded, semi-circular top that forms an arching effect. Arched windows are an excellent choice for homeowners looking to add an elegant touch to their spaces. Though historically used in traditional architecture, arched windows are gaining popularity in modern home design. They can be used in these scenarios to soften the otherwise sharp appearance of geometric structural features. Arched windows are typically classified as a specialty shape, so they’ll likely have higher labor and installation fees than traditional ones.

Awning Windows
Awning windows are hinged at the top, allowing them to open outward. These windows typically open and close with an easy-to-use crank mechanism, making them a great choice for hard-to-reach spaces that need extra fresh air and light. The crank allows you to open the window to various angles for different ventilation and privacy needs. This feature makes awning windows popular for bathrooms, bedrooms, and kitchens.

Slider Windows
Slider windows are mechanically quite simple, consisting of side-by-side windows that slide horizontally along the top and bottom tracks. In some styles, both windows slide, while in other styles, one window is fixed while the other moves side to side. Slider windows are popular in mid-century modern homes styles (they were popular in new construction during the 1950s and 60s). Sliders are a good choice when you need to constantly open and close your windows.

Bay Windows
A bay window refers to a combination of windows that together form a unit that extends outward from the wall surface of the house. These windows are called bay when the shape of the extension is more-or-less square, and are known as a bow when the shape is more curved. Bay windows are traditionally formed with a fixed center picture window flanked on the sides by one or more pairs of double-hung or casement windows. A bay window can be used as a visual centerpiece in large living rooms, family rooms, or parlors. They very often look out on an attractive view or a landscaped setting, such as a front yard.

Bow Windows
Similar to bay windows, bow windows extend beyond the exterior wall, but sweep away from the wall in a graceful arch of four, five, or six windows. This elegant window style is typically larger than the bay window style and has more glass area because of a curve in lieu of corners. As with bay windows, adding a window seat to your bow window can be a quick and easy room addition. If you’re adding a bench seat below your window, consider it an opportunity for extra storage. Bow window installation typically involves the same considerations as those for bay windows. However, bow windows include more windows and framing, which will add to your overall material and labor costs.

Casement Windows
Casement windows are similar to awning windows in the sense that they’re hinged to the frame. The difference is that casement windows are hinged on one side and function like a small glass door. The homeowner can open and close their casement windows by maneuvering a crank at the bottom of the frame. This feature makes casement windows a great choice for tight, hard-to-reach areas. Casement windows are one of the most energy-efficient window models on the market. They close securely with a weather-tight seal and multiple locks that keep outside air from entering the home. They’re a good choice for areas like bathrooms and kitchens that need quick, effortless ventilation.

Picture Windows
Picture windows have large panes of glass without any crisscrossing rails. They create a “picture” by providing an unobstructed view of the outside of the home. Picture windows are sometimes called fixed windows because they’re permanently set in the wall with no ability to open. Picture windows are a good choice if you want a better outdoor view or for adding more natural light to any space in your home. However, picture windows aren’t useful for spaces needing extra ventilation since their fixed, inoperable design prevents them from being opened.

Transom Windows
Transom windows are named as such because they are located over top of a window or door’s transom– this is the beam that separates the top of the window or door from the rest of the wall. Consequently, transom windows can come in many different shapes, styles and designs, but retain the name due to their location. The only general difference in transom windows installed above doors and those installed above windows is the size—they generally match the width of the transom. Transom window date back to the days when air conditioning had not yet been invented. Back then, transom windows were opened and closed to facilitate cross-ventilation. Today, it is rare to see a transom window that opens. Typically these windows are now used for letting in additional light, especially in morning or evening hours. If they do open or close, this is usually operated by an electronic switch.

Replacement Window Factors
If you’re considering replacement windows, do the math to find out just how cost-effective new units would be. One way is by completing a home energy audit. Whether you hire a professional or try the DIY route, this energy efficiency checkup for your home will give you a sense of where the major energy-loss areas are and how serious they are. It’s essential to get a good read on where the thermal transmission problems are in your home before you embark on a full replacement-window renovation. You don’t want to lay out five figures for a whole-house window makeover when your real problems might have been solved by a tube of caulk, some weatherstripping or a few storm windows.

Framing Materials
The window frame material you choose will affect a window’s price, appearance, and functionality. We’ll discuss some common window frame materials and their potential pros and cons.

Aluminum
Aluminum window frames are lightweight yet durable, making them a popular choice for larger windows. They’ll support your home’s windows while withstanding environmental factors outside. Their durability also lends to fewer maintenance needs and less cleaning, which greatly benefits hassle-free homeowners. A downside of aluminum windows is that they aren’t very energy efficient. Aluminum is a poor insulator, which means outside temperatures will likely weasel their way into your home through the frames. For this reason, aluminum frames aren’t a good choice for homes in cold environments.

Fiberglass
These are technically composite windows, since they’re made of a mixture of glass fibers and polyester resins, but they’re often discussed independently of other composite windows because that term is increasingly being used solely to describe the wood-pulp-and-plastic composite material. Fiberglass windows are more expensive than other similarly equipped window units, but their selling points are many: They’re extremely energy efficient thanks to their low thermal conductivity; they’re the strongest and most durable windows on the market; unlike vinyl windows, they can be repainted several times; and they don’t twist or warp like vinyl or wood frames can.

Wood
Wood windows offer the best insulative value, though they also require more upkeep than vinyl, wood-clad or aluminum frames. Because of the potential for rot, they may not be the best choice for extremely humid or rainy climates. A well-built wood window will stand the test of time, however; many original wood windows in older homes are still in good shape thanks to the high-quality cut and species of wood used.

Wood-clad
Wood-clad windows seemingly offer the best of both worlds: a low-maintenance exterior (usually vinyl or aluminum) and a temperature-transfer-resistant wood interior. But clad windows can be prone to water intrusion, which can cause rotting, especially in the sills and jambs, where water tends to pool. Proper installation of wood-clad windows should include use of waterproof rubber membranes around the cladding as well as a stand-alone flashing assembly called a sill pan. The sill pan drains any water that gathers around the sills and jambs, minimizing moisture intrusion.

Vinyl
Vinyl window frames are a cost-effective option suited for many homeowner’s needs. Vinyl frames are made of PVC, a plastic material resistant to mold and water damage. The material doesn’t need staining, painting, or sealing to remain in top condition. While this is a major benefit for homeowners seeking a low-maintenance frame option, those seeking highly customizable window frames might see it as a drawback. Vinyl window frames once had a reputation for being low quality, but this is no longer the case. Improved high-quality vinyl materials are durable, long-lasting, and provide excellent insulation around your windows.

Energy Efficiency
The U.S. Department of Energy estimates that heat transfer through your windows is responsible for 25-30% of residential heating and cooling energy use. This is no small amount considering that the average home spends approximately $1100 annually on these costs. When you select new windows, there are four main factors that influence energy efficiency. These factors are:
• Window function
• Frame material
• Glass type
• Spacing and gas fills

Window Function
When it comes to window function, fixed windows or picture windows are the most energy efficient because the sashes are non-operable and therefore are fully sealed to the window frame. This lack of seams and moving parts means that virtually no air can penetrate the windows, which provides impeccable energy efficiency, but does so at the cost of being able to open and close your windows. In terms of operable windows, hinged-sash windows such as casement and awning windows are typically the most energy efficient as they create a firm weathertight seal when closed.

Frame Material
There are many different window frame materials on the market, ranging from vinyl to wood to metal to fiberglass, and more. Of all of these, vinyl tends to be the most energy efficient material as it has better natural insulating properties than fiberglass and metal and won’t warp or deteriorate as wood windows often do over time. Vinyl also has a high R-value, which means it effectively reduces heat transfer—keeping warm air inside your home in the winter and preventing hot outside air from seeping inside your home during the summer months.

Glass Type
The specific glass used in windows is extremely important in ensuring energy efficiency in your home. Though many may think that the glass in a window is simply just glass, this couldn’t be further from the truth. As a matter of fact, it is one of the most complex features in any window. From its quality to its coating, there are many factors to take into account when deciding on which features you want your glass to have:
• U-Factor: A window’s U-Factor measures the rate of heat transfer and tells you how well the window insulates. In terms of energy efficiency, this means that the lower the U-factor for a window is, the more efficient it is.
• Solar Heat Gain Coefficient: The SHGC of a window describes how well a window heats up from the sun. It is typically more energy efficient to have a low SHGC so less energy is placed towards cooling your home. This is especially important in warmer climates (not so much here in MA) and in homes that do not have a lot of shading.
• Visible Transmittance Rating: The VT rating of a window measures the amount of light it allows to pass through it. A higher VT rating is ideal as this allows more natural light to shine through your window and into your home.
• Low-Emissivity Coating: Low-E coating in a window’s glass creates insulation through a glaze that is combined with multiple panes of glass. Though low-emissivity coating tends to cost 10-15% more than other methods of glass insulation, it also reduces energy loss by 30-50%. This is extremely important from an energy efficiency perspective as well as an economic one.

Insulative Glass
Insulative glass has two or more panes, with a gap between the panes created by a spacer. Then, manufacturers fill the space with air or dense gas that acts as an insulator. Insulated glass goes by many names, including double-pane, double-glazing, triple-pane, and triple-glazing. These windows are a “unit” because they contain many parts rather than one piece of glass. And because insulated glass units are filled with gas and sealed, you can’t replace just one piece of glass or make repairs.

Types of Insulated Glass
All insulated glass has similar components- two or more panes of glass, sealed, separated, and filled with an insulator. The difference between the types is what fills the space between the panes:
• Air-filled: As the name implies, air-filled glass has air between the glass panels. Air provides increased energy efficiency, but not as much as gas-filled options. The benefit is the seals last longer than on gas-filled units. Air-filled insulation is also the least expensive.
• Argon-filled: Argon is a dense gas and the most popular window-insulation option. Argon-insulated windows can increase energy efficiency by about 10% compared to air-filled units. Many argon-filled windows also have Low-E coatings to prevent heat leaks.
• Krypton-filled: Krypton gas is denser than argon and popular in windows with small gaps between the panes. Krypton is an excellent insulator but comes at a higher price.
• Xenon-filled: Xenon is a dense, expensive gas. It’s most popular in commercial architecture, where there are large spans of windows. Xenon might not be worth the cost in residential spaces.

Life Span and Replacement Costs
Selecting the right windows also depends on how long you plan to stay in your home. You’ll want to determine the life span of different window materials to understand the value they’ll retain over time. Plus, the longer a certain material lasts, the longer you can go without paying for costly replacement windows. Some framing materials like aluminum and fiberglass cost more to install and replace but last much longer than wood or vinyl. If you plan to live in your home for the foreseeable future, a larger investment will likely be worth the high-quality materials you’ll get.

After determining the quality and life span of different window framing options, you’ll want to consider how much it could cost you to replace entire windows. Windows generally need to be replaced every 15 to 20 years. Your windows will likely exhibit frequent repair needs around the 20-year mark. You may notice cracked panes, warped framing, foggy glass, and stubborn sashes. At this point, replacement is likely the solution to the repeated repairs and higher energy bills old windows cause.

Think Long-term
Now that you know all the ins and outs of windows, you’re ready to start shopping for the best option for your home. Appearance is likely your top priority when choosing new windows, but life span and energy efficiency are also important factors to consider. These qualities can significantly affect the return on your window investment, so don’t forget to think long-term.

For Further Reading:
• Forbes.com has an excellent overview of window types at https://www.forbes.com/home-improvement/windows/types-of-windows/.
• “Pros and Cons of Popular Window Styles” by The Spruce.com is presented at their page, https://www.thespruce.com/most-popular-window-styles-1822931.
• EcoHome presents their thoughts on this subject in their article, “Our top tips for buying high-performance windows” found at: https://www.ecohome.net/guides/2263/high-performance-windows-what-to-look-for-when-shopping/.