In today’s economy, it is important to conserve expenses and energy. An increasing trend in the building and remodeling industry is the use of energy efficiency. New innovative products have been emerging and promoting energy efficiency to help people use less, therefore spending less.
It is amazing how much information is out there on the energy efficiency of windows. However, no resource on the web exists that incorporates all of the different factors that come into play when choosing a replacement window. In the eye of the consumer, it is confusing and very difficult to know how to choose the right windows for your home. This info graphic helps break down all of the elements that will help you choose the right and most energy efficient window for your home.
When looking into replacing your current windows there are six questions that you should answer first:
- Why are you replacing the windows?
- How much maintenance are you willing to do?
- What are your performance expectations?
- How durable would you like the frame of your windows to be?
- What is the budget for replacing your windows?
- What is your current climate?
These questions will help tailor the types of windows you should be looking at.
Section 1: Triple Pane Window Benefits
Replacing your windows can yield many benefits. But perhaps the most appealing benefit, are the savings that you are likely to gain by having better insulated windows.
According to ENERGY STAR, replacing your single or double pane windows with triple pane windows can save an average of $126 – $465 per year. The amount of savings varies depending on the specifications of the window. Windows with more insulation, glazing, etc. will provide more energy efficiency, therefore saving you more money.
In addition to the potential savings of replacing your windows, low-e coatings and glazes prevent premature fading of interior surfaces in your home. The way the coatings work is that they block and reduce the ultraviolet rays coming through your window. Depending upon the climate, different coatings can be used to control the temperature of your home. Buying the correct type of replacement window for your climate area will lead to a more comfortable and consistent temperature in your home.
Another benefit to choosing more energy efficient windows is the potential reduction in pollution released into the environment. Pollution is a growing issue in the United States, which has influenced the recent demand for energy efficient and green products. By choosing energy efficient windows, you will help reduce your carbon footprint.
Section 2: Understanding The Window Label
Trying to interpret the values on a window label is an intimidating task for those that are not familiar with the industry. In order to choose the most energy efficient window for your home, a general understanding of window terminology is extremely helpful.
There are three main sections to a window label: the qualifications, the “extras” and the performance ratings. One key indicator of an energy efficient window is the ENERGY STAR logo. The purpose of this logo is to distinguish the products that have met and/or exceeded the energy star standards. All energy star qualified products must meet strict energy performance criteria. It is always important to make sure the window you choose for your home has the energy star stamp of approval. This will lead to greater energy cost savings for your home. The label will also tell you how many states that this type of window is qualified for. Meaning what and how many types of climates the window is equipped for.
The National Fenestration Rating Council (NFRC) created and upholds a uniform national rating system for determining the energy performance of building elements. To openly communicate the rating of windows, they created the window label that houses the performance ratings for VT, SHGC, U-factor, AL and CR. The NFRC logo on the window label ensures that the window has been rated accurately. Testing on all products is done before determining the ratings of a window and only after the window has been certified, can a company display the NFRC logo on their product.
The next section of a window label is the “extras” section. This part of the label will house the retailer’s name, frame material, and list the additional enhancements to the window. This part will outline if the window is low-e, has insulation and what type, and any glazing that is applied to the window. Colder climates should always look for a window with a low-e coating. Low-e prevents cold air from entering your home and reduces the amount of cold air that is lost through the window. Glazing is another important element that high quality windows will have. Glazes will aid in keeping solar heat out of your home while also reducing the VT entering your home.
The performance ratings section is a little trickier to understand but aids in choosing the best window for the climate in your area. The goal of these specifications is to provide homeowners with the most energy efficient window for the climate in which they are located. To do this, you have to understand what the performance ratings mean and what range of numbers you should be looking for.
The U-factor measures the total heat flow through a window to the outside air. U-factors of 0.3 or less are ideal for all climates. A lower U-factor most benefits colder climates, however significantly benefits warmer climates when combined with a low SHGC. The lower the U-factor, the better the windows insulate.
SHGC stands for solar heat gain coefficient. This rating reports on the ratio of solar heat that passes through the glass. For climates that have very high temperatures, you want to look for a window that has a low SHGC, typically around 0.2. However, for colder climates the SHGC should be higher, around 0.4. A lower number indicates that the window will allow less solar heat to pass through the window, lowering the amount of air conditioning used. Inversely, a higher number indicates that more solar heat will pass through the window to aid in heating your home.
Visual Transmittance, also known as VT, is the amount of visible light that enters your windows. VT is the factor that affects the amount of light that is let into your home. Every climate should look for a higher VT with a low-e coating.
Air leakage is air that escapes through small gaps in windows. Like VT, all climates should look for a lower value to prevent air from leaking out. The lower the AL, the less air escapes.
Condensation resistance helps prevent water from building up on your windows when the internal and external temperatures are opposite of each other. The higher the condensation resistance for a window, the less water build-up the window allows.
Section 3: How Windows Work
In order to choose the best replacement windows for your home, understanding the way a window works is important. There are four main factors that windows are designed to either increase or reduce.
The first of these factors is radiation. Radiation is the movement of infrared heat energy through the glass. Low-e coating helps bounce radiation waves back inside the home, reducing winter heat loss. Specialized glazes reduce the amount of summer heat gain let into your home. This in turn helps reduce the amount of air conditioning used during warmer months.
The second factor is conduction. Conduction is the direct transfer of heat through the window from the inside to the outside of your home. Conduction and radiation allow heat to escape and cause greater use of your heating or air conditioning.
When warm air circulates and hits the window, the window absorbs the heat and releases cold air that sinks towards the floor. This process is called convection. To reduce the effects of conduction and convection, insulators are used in windows. This prevents heat transfer and keeps the window from absorbing the heat and releasing cold air in its place.
Air leakage is the amount of indoor air that escapes through gaps in the window frame or weather-stripping. Ideally, high quality windows will prevent air from escaping through gaps between the window and the frame.
To address each of these actions, coatings, glazes, and insulation is made for windows to combat opposing temperatures. These enhancements keep warm air in and cold air out during the colder months. Likewise, during the warmer months, the warm air is kept outside your home while maintaining a cooler temperature inside.
Section 4: Choose An Efficient Window Pane
On the market currently, there are three types of window panes: single pane, double pane and triple pane. Single pane windows are comprised of one pane of glass separating the inside of your home from the outside. This type of window is the least efficient due to the lack of insulation it provides. Single pane windows are often combined with storm windows or screens, however both provide little to no insulation from harsh weather conditions.
Double pane windows consist of two panes of glass. The panes are separated and sealed which creates an insulated pocket of air. To further insulate the space between the panes, they can be filled with either argon or krypton gases. These gases have a higher resistance and let less heat escape through the panes of glass. Today’s double pane windows typically include a low-emissivity, also referred to as low-e, coating that helps further insulate the window. Although windows that have a low-e coating are slightly more expensive than single-pane non-insulated windows, they have the potential to reduce energy loss by as much as 30%-50%.
Triple pane windows are comprised of three panes of glass and are the most efficient of the three. Between each pane the space is filled with an inert gas, such as krypton or argon, which acts as an insulator. The added benefit of triple pane windows is that there are two spaces available to fill with this gas, inherently further insulating the window and preventing heat loss.
Section 5: Frame And Sash Materials
There are typically five frame and sash materials to choose from to accompany your window. Among the five materials, vinyl is the most popular. Vinyl provides a middle ground between the highest priced, highest quality material and the inexpensive and low quality material. Simply put, vinyl produces the highest quality for the best price. The durability of vinyl coupled with the thermal resistance it provides, makes it one of the most sought after materials on the market. Plus vinyls provide a lifetime warranty instead of the average 10 year warranty. Vinyl is ideal for those who do not want to spend a lot of time with the maintenance of their windows and have a smaller budget to work with.
Although less desirable, people also equip their windows with materials such as wood, aluminum, composite and fiberglass. Genuine wood frames are typically higher in price, require a lot of maintenance and provides a warranty of 10 years. Wood provides good thermal resistance however the durability of the wood depends on what type of wood you are using.
Aluminum is the least desirable window frame material on the market. Aluminum provides little to no insulation and only comes with a 3 year warranty. The durability of this material is good and it is an inexpensive material.
Composite have average thermal resistance and an average durability. It requires low maintenance and comes with a 10 year warranty, however for every advantage there is a disadvantage. Composite is extremely expensive which is the characteristic that tends to turn people off from the material.
Rounding up the commonly used frame and sash materials is fiberglass. If you are looking for a cutting edge material, this is it. Fiberglass has very good thermal resistance and durability and has a 10 year warranty. The only drawback to fiberglass is that it is very high in price. Due to the exorbant cost of fiberglass, people tend to choose vinyl, which performs just as well however costs significantly less.
Replacing old worn out windows yield many benefits, including significant reduction in energy costs. To purchase the best replacement window for your home, many factors need to be taken into consideration. Defining your climate will guide you through the process of choosing a window. Each climate has different standards and performance criteria. This guide will help assist you in choosing the most energy efficient replacement windows for your home’s needs.