An experiment was conducted to investigate the effect of textile properties (openness of weave, fiber cross-section, fiber structure, and 2-pleat characteristics) on the development of directional shades. Textiles used as shading materials can control the amount of natural light entering an interior environment, as well as offer energy savings within buildings in year-round warm climates by blocking or redirecting unwanted solar rays.
Findings
 Use fabrics for shades that are non-woven and have high yarn counts to reduce glare.
Choose fabrics that possess directional properties allowing them to redirect unwanted solar energy.
Evaluate the fabric's structure, as that characteristic will determine amount of light transmitted along with the overall distribution pattern.
Provide directional shading that achieves adequate light transmittance, redirects incident light upward, reduces glare, and improves both daylight performance and shading performance (limiting solar load).
Select a sheer plain-weave fabric for areas that need light transmittance that is soft and pleasing.
Use a cylindrical clear filament textile such as a sheer plain-weave with a reflective coating (135 degree coverage) on the topside of the fabric to redirect light upwards, preventing glare. Light must be directed above the horizon line to eliminate glare perceived by building occupants.
Provide shades with a variable tilt angle to allow for adjustability of the device by building occupants as needs will change depending on the time of day, season, and building orientation. This could also be accomplished using several reflective tapes oriented at different tilt angles to simulate a round reflector.
Maximize the redirection of incident beams with the pleat structure and pleat orientation, however, do not count on pleating alone to decrease glare and redirect light. The combination of fabric characteristics and Z-pleating is essential to achieve the desired effects of improved day lighting and reduced glare.
Assess sun exposure, desired energy efficiency, and light transmittance when selecting window coverings; be aware of the properties of fabrics used for directional shading purposes.
Key Concepts
Fabrics with higher yarn counts reduced glare but also lowered overall light transmittance.
Nonwoven fabrics have the ability to prevent glare, as they disperse incoming light throughout the space, instead of in one direction (Grasso & Hunn, 1992).
Fabrics consisting of a sheer plain-weave with the Z-pleat configuration and added specular reflecting tape provided the largest vertical dispersion ratio (VDR).
The use of background fabric and pleat structure decreased light transmittance, as demonstrated in tests of triaxial weave, rip-stop nylon weave, and open mock leno weave fabrics.
Background fabric with increased density such as Z-pleated, nonwoven, and spunlace oriented-web decreased the efficiency of reflecting tape.
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