U-Factor, also known as non-solar heat flow, is an important metric when comparing windows. It tells you how well they will insulate your home against outside influences.
In mixed climates such as the North and Midwest that require both heating and cooling, a low U-factor can help reduce energy costs.
U-Factor
The U-Factor is an important factor in assessing how well your new windows will insulate against winter heat loss and summer heat gain. It measures the rate at which heat transfer occurs through a window, both from one side to the other and inside to outside. It also takes into account airflow or convection patterns as well as how much radiated or reflected energy can pass through glass.
The rating of a window is determined by its U-factor, which is displayed in an orange box on its label. This rating system, developed by the National Fenestration Rating Council (NFRC), measures energy efficiency of home components like windows, doors and skylights.
A higher U-factor indicates that windows may allow more heat to escape during wintertime, requiring your heating and air conditioning systems to work harder in order to keep your house comfortable. Lowering the U-factor will save you these unnecessary costs and improve your home’s energy efficiency.
Window manufacturers can reduce the U-factor of their products by employing gas fills such as krypton and argon, along with low-E coatings that block radiant heat transfer to the exterior. When combined, these features significantly lower your windows’ U-factor, helping you save money and stay comfortable all year round.
Some window manufacturers also employ thermal breaks, which are pieces of plastic that stop airflow across a frame. These breaks can significantly lower your windows’ U-factors and make them more energy-efficient.
The lower the U-factor of your new windows, the better their insulating performance. As a result, you will enjoy warmer temperatures in winter and cooler ones in summer – cutting down on energy bills while decreasing your carbon footprint.
When looking for replacement windows, it’s important to compare your choices against the NFRC rating system in order to find the ideal fit for your home. A reliable window contractor can provide all of these NFRC ratings as well as explain how they affect energy efficiency in your house.
Solar Heat Gain Coefficient (SHGC)
When purchasing windows, one of the most essential factors to consider is their Solar Heat Gain Coefficient (SHGC). Many window companies display this number on their products as an effective way for you to assess how well a particular window will perform in your home.
A good SHGC rating can make all the difference in a hot climate and keep your home more comfortable during hot summer days. Furthermore, it could save you money on air conditioning costs.
When selecting window u factors for your home, climate is one of the most important factors. In colder regions, lower SHGC values are preferred while higher SHGC levels can be found in warmer ones.
The EPA suggests different window u factors for each climate zone, depending on how much a building must be heated or cooled. In warmer climates where heating or cooling is predominant, lower SHGC values are ideal as they help cut air conditioning costs. Mixed climates with more solar heat gain during winter months may benefit from higher SHGC values.
Additionally, your home’s location and orientation will determine the ideal window u factor for a particular window type. North facing facades receive less solar exposure so require more glass area to achieve an adequate u factor; on the other hand, south-facing facades receive more sun exposure and require a smaller glazed area to achieve optimal efficiency.
For a more in-depth explanation, read our article on U-Factor and SHGC.
Low U-Factor windows will keep your house cooler in the summer and higher SHGC numbers keep it cozy during wintertime. Selecting the appropriate window type for your climate is key to keeping your home cozy and energy efficient all year round.
Similar to the U-Factor, the Solar Heat Gain Coefficient (SHGC) measures how much solar heat enters windows and is absorbed by them. This heat then radiates back into your home, causing its interior temperature to increase.
Structural-Design Pressure (DP)
When upgrading your home with high impact hurricane windows, the u factor is an essential factor to take into account. This simple number measures how much heat is lost from each surface in BTUs when exposed to different temperatures.
Another essential window rating is the Structural-Design Pressure (DP). This test measures the strength and durability of a product through three tests that assess air infiltration, water infiltration and structural load resistance. When testing windows or doors for quality assurance purposes, the design pressure test can help determine their resistance to air infiltration, water infiltration and damage due to weathering or impacts.
The higher the DP rating, the stronger your window or door is at surpassing these benchmarks. For instance, a window with a DP rating of 50 has passed structural load testing of 75 pounds per square foot or 200 miles per hour winds; on the other hand, one with only 50 pounds per square foot or 125 miles per hour winds is only capable of withstanding 50 pounds per square foot winds.
To calculate a Durometer rating (DP rating), products are attached to a wooden frame and put through a pressure test. During this procedure, the air inside of the product is gradually reduced until it breaks, at which point 1.5 times its design pressure will have been reached for 10 seconds – at which point your window has passed inspection.
Although DP ratings are the most commonly used rating system for windows, there is also an alternative performance grade system called PG. This rating was created to address some of the drawbacks associated with using DP ratings.
PG ratings require all components of a window or door to undergo all three resistance tests, rather than just two. This makes it much harder for manufacturers to conceal weak points and provides more precise measurements of an item’s energy efficiency.
Therefore, when shopping for new windows you may want to take into account DP or PG ratings. Visit any of our locations today to speak with an expert about which windows meet the necessary ratings for your project.
Visible Light Transmittance (VT)
When considering energy efficiency, the windows u factor is one of the most critical metrics you can look at. It indicates how well a window will keep heat out and cool air inside, as well as block out unwanted solar radiation.
Typically, a window’s u factor is calculated at its center of glass; however, it can also be determined by the frame or sash. These factors alone do not always account for all that affect the U-factor; other elements like material, thickness and even shape all contribute to overall U-factor of a window.
In addition to a window’s u factor, visible light transmittance (VT) should also be taken into consideration when purchasing new windows. VT measures how much natural sunlight will pass through the glass when open or closed.
The National Fenestration Rating Council (NFRC) rates visible transmittance on a scale from 0 to 1, with higher numbers signifying more natural light let into your home. It’s important to remember that having an impressive VT score does not guarantee energy-efficiency; other metrics like solar heat gain coefficient and air leakage must also be taken into consideration when assessing how efficient your windows really are.
Another crucial element in window performance is the type of glass used. Different varieties can help maximize natural sunlight penetration, thus decreasing air conditioning costs.
Some glass options can even reflect sun rays when they hit their surface, preventing solar heat transfer and keeping your house cooler in summer. This is especially beneficial for homeowners living in hot climates since it could save money on cooling costs!
Selecting windows with high u factor and VT ratings can help reduce your home’s energy bills. Not only that, but it will also make you feel more comfortable in your surroundings and add some visual interest to the living space.
