Shade Fabric Choice
CHOOSING THE correct window shade fabric is the most important part of shade selection. The choice you make will depend on your desired outcome. Do you want a certain look, or is obtaining a specific performance outcome your goal? There are hundreds of options from which to choose: differences in color, openness factor, material, and weave all determine the look and performance of each fabric, and the different combinations mean that, whatever your desired outcome, there is a fabric solution for you.
But how does one find that solution?
Looks vs. Performance
First, ask yourself a simple question: What is more important—aesthetic considerations or performance? If your concern is mainly to fit in with a specific design scheme, then the choice is probably a simple one. By looking at sample swatches, or using Draper’s online Window Shades View-Through Simulation Tool (www.draperinc.com/windowshades/viewthroughsimulator.aspx), you can soon identify the look you are going for.
Even if you are more interested in aesthetics, however, you should take some time to think about performance. Shade fabrics have a big impact on the room. They can reduce glare, keep solar heat gain to a minimum (thus reducing utility costs), allow or restrict view-through to the outdoors, or provide privacy. So, even if the choice of a certain color or pattern and weave gives you the look you want, does it create other problems, such as too much glare at certain times of day, or too much of a view into the space from the outside?
Consider the conditions
When selecting shade fabrics, it’s important to consider the space—the conditions, how and when it will be used, and its location. Is glare an issue? Take into account not only glare from direct sunlight on interior surfaces, but also from sunlight on exterior surfaces, such as other buildings or nearby water.
Also, think about solar heat gain. Depending on how the building is oriented, there will be times of the day and year that could see a lot of solar radiation hitting the windows. Energy from the sun is short wave and carries little heat. Heat is only produced when the solar energy is absorbed by a surface such as carpeting or furniture and is radiated as long wave infrared (IR) energy. Reflected solar energy, then, is not an issue, so for the best performance in this area you want a fabric that will reflect more solar radiation and transmit or absorb less.
Information on how much solar radiation is transmitted, absorbed, and reflected by fabrics used on Draper shades is available on swatch cards, or online at www.draperinc.com/windowshades/fabriclist.aspx. When you click on individual colors, numbers are provided for solar transmittance, reflectance, and absorption. Taken together, these numbers make up what’s called the “Solar Heat Gain Coefficient.” The lower the coefficient, the better.
If your concern is preventing light pollution—light escaping out of the space at night—then an opaque fabric or perhaps 1% openness would be the best choice.
Views through to the outdoors are very important— they increase worker comfort, thus helping to improve productivity and employee well-being. Certain fabrics will allow a better view out, but might then allow more solar radiation in.
Whatever your choice, and whatever your reasoning, shade fabric selection must be part of an overall daylighting strategy that makes use of all sorts of tools—exterior shading products, interior shades, light shelves for bouncing light further in, and other methods. It’s not about keeping the sun out; it’s about utilizing it in a way that increases comfort and conservation, and doesn’t create a less comfortable environment.
Color and Openness Factor
These two characteristics are the most important in getting the right fabric solution. Woven shade fabrics are made with coated yarns, with space between the fibers. Openness factor is the percentage of that space in the weave. The smaller the openness factor, the less light gets through. The higher the openness factor, the more space there is. Obviously the higher the openness factor, the better the view-through characteristics will be. However, that also means more solar radiation getting through into the room.
Color also has a major impact on both view-through and solar heat gain. The darker the fabric, the easier it is to see through, and the lighter the color, the harder it is to see through. Generally the darker a fabric is, the less solar radiation is reflected, so it can sometimes be difficult to find a happy medium between view-through and thermal comfort.
There are a couple of fabric technologies that help make this choice a little less difficult. There are duplex fabrics available with a light exterior and a dark interior. In addition, fabrics are available that are treated in a special process that provides high reflective values on darker colors.
The weave is the pattern of yarns as they are woven together. There are several types of weave, and the differences are more than just aesthetic. The weave has a big impact on the performance of the fabric.
The Basket weave is the most common pattern. It is typically a two by two pattern—that is, two strands of yarn, not just one, woven in an over-under pattern. Because this weave is non-directional, it will look the same no matter which direction the fabric is hung. That means wider windows can be covered.
A Twill weave is a diagonal pattern that allows the manufacture of fabrics that are light on one side and dark on the other. This is accomplished by displacing the yarns so the vertical and horizontal threads (known in the fabric industry as warp and fill) are disproportionately separated. A Jacquard weave allows unique designs and custom patterns. This is made possible by individually controlling each yarn on the loom.
Most blackout shades are woven, and the fabric is coated or laminated, but some are made of another material, such as vinyl. A blackout shade is just what the name implies: 0% of solar radiation gets through the fabric. With the use of side and sill channels, a complete blackout with no light leakage can be accomplished. This can be advantageous for privacy, and for maximum reflectance of solar heat, but can also be inconvenient, since the only way to see out or allow daylighting in is to raise the shade.
Best of Both Worlds?
There is a way to get the advantages of two different types of shade fabrics on one window. Perhaps you want to have a fabric that allows view through during the day, but you want the privacy of a blackout shade at night. With a dual roller system, two shades are built into the same headbox. Either or both can be lowered as needed.
Vinyl Coated Fiberglass and Polyester Yarns
Vinyl coated fiberglass and polyester fabrics are popular and widely used materials to make shade fabrics. Each of these materials has its individual benefits and advantages.
For an in-depth look at the differences between fiberglass and polyester fabrics, go to http://www.draperinc.com/FlipBook/shadefabricchoices/index.html
Quite often a major factor in determining what shade fabric to use is how “green” it is, and what impact it has on the indoor environment as well. The majority of woven shade fabrics are made from fiberglass or polyester yarns. There are fabrics available that are both 100% recycled and 100% recyclable, while others will contain some percentage of recycled material. That information is found on swatch cards, and technical information on fabric web pages.
Because lead can be a cheap way to improve flame retardancy and UV stability in shade fabrics, it’s also important to check product information about heavy metals and other chemicals. There are various ways fabric manufacturers indicate their products are free of lead. Look for fabrics that are certified to either U.S. Consumer Product Safety Commission Section 101; ANSI/WCMA A 100.1-2007 for lead content; REACH (EC 1907/2006 compliance; or RoHS Directive 2002/95/EC.
Vinyl coated fiberglass and polyester fabrics—and vinyl blackout fabrics—usually contain PVCs. All PVCs contain plasticizers, which in turn contain phthalates. Fabrics are becoming available which utilize bio-based plasticizers, however. This greatly reduces the amount of petroleum used, contains no phthalates, and lowers greenhouse gas emissions. More than simply having bio-based plasticizers, however, fabrics where the yarns themselves are 100% plant-based are also being introduced. There are also several fabrics which are PVC-free.
Speaking of emissions, fabrics can emit volatile organic compounds (VOCs) into the air. This is known as off-gassing. To reduce this risk, utilize fabrics that are Greenguard or Greenguard Gold certified by UL that emission levels meet the EPA standard for low emitting products, and that the product does not release toxins or carcinogens into the air.
In some situations, such as health care, schools, home, and hospitality, there also may be a concern about mold and mildew developing on shade fabrics. Shade fabrics that include antimicrobial protection to inhibit the growth of bacteria, mold, and mildew are available. Antimicrobial technology—such as Microban—is infused into the fabric. Certifications to look for include ASTM 2180, ASTM G22, ASTM D 3273, and the Greenguard Mold and Bacteria Standard ASTM 6329.
Another major safety factor to consider is flame retardancy. Although there are no national requirements for flame retardancy in residential applications, there are national and local requirements in commercial areas. CA Title 19, considered the most stringent in U.S., and NFPA 701 are the most common standards, along with ASTM E 84 and NFPA 101. Most Draper fabrics meet one or more of these standards.
These are all factors in determining the best solution for conditions and aesthetic requirements.
For a complete list of fabrics available on Draper shades, including descriptions, selection tools, openness and fenestration data, and more, go to www.draperinc.com/windowshades/fabric.aspx.
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