Great windows can make a home look and feel great. When choosing replacement windows, it's good to know what choices you have and how they can affect the appearance and energy efficiency of your home. The following offers several options for your new window replacements.
Single, Double or Triple Pane?
Just as the name implies, single pane windows consist of a single pane of glass. Single pane windows are the most affordable choice, but they're also an increasingly rare choice for good reason. These windows simply don't offer the energy efficiency features that double and triple pane windows have. These windows also tend to let in the most sunlight, which could be a good or bad thing depending on your preferences and energy efficiency concerns.
Double pane windows feature two panes of glass separated with a spacer. The gap left between the two panes is often filled with argon or krypton glass to insulate against outdoor temperatures. Double pane windows initially cost more than their single pane counterparts, but the energy efficiency they offer can help offset those initial costs. As NPR's Cheryl Corley notes, one homeowner reduced her heating bills by $25 to $50 per month just by installing double pane windows.
Triple pane windows add an additional pane of glass, as well as an additional spacer. These windows usually offer U-factors that are up to 30-percent better than double pane windows. In addition, triple pane windows tend to be more durable than their double pane counterparts. On the other hand, triple pane windows tend to be more expensive and heavier than comparable double pane windows. These windows also let in less light than single or double pane windows.
Enhanced Low-E Glass
Single, double and triple pane windows can be enhanced with low-emissivity or "Low-E" coatings. These coatings consist of a thin, transparent layer of metal oxide. When applied to the glass surface, the Low-E coating deflects infrared heat and ultraviolet (UV) rays, preventing them from entering your home. During the winter months, Low-E-coated windows can also help hold heat indoors, preventing extra energy costs that come from combating heat loss.
There are two types of Low-E coatings: passive and solar control. The former allows some infrared energy to pass through, making it ideal for cooler climates where you'll want some passive heating via your windows during the winter. The latter actively blocks a large amount of infrared energy, making it effective for warmer climates.
If you live in an area that is prone to hurricanes, tornadoes or high winds, then you may want to consider investing in impact-resistant windows. These windows usually consist of a heavy-duty frame containing impact-resistant glass panes. There are two types of impact-resistant windows:
- Laminated windows feature a shatter-proof membrane located between two panes of glass. The membrane comes in various thicknesses and it can also be ordered in various color tints.
- Filmed windows feature a protective film applied over the window panes. These windows are less expensive than their laminated counterparts, but they're not as durable.
Check the U-Factor
It also pays to check the energy performance ratings of your new windows. One rating to pay close attention to is the U-factor, as it measures the rate of heat flow through your window. With the U-factor, lower numerical values indicate better performance. In cold climates, you'll want to look for windows with a U-factor between 0.17 and 0.39. In warm climates, you'll want to keep the U-factor under 0.30 and pair it with a solar heat gain coefficient (SHGC) under 0.30.
You'll also want to pay attention to the visible transmittance (VT) rating. This indicates the amount of visible light that's able to pass through your new windows. VT values of 0.30 to 0.70 are common for most double and triple pane windows -- the more light the window allows, the higher the VT value. Be aware of windows with VT values under 0.40, as these tend to give a grayish tint to your outdoor view.