Physics:Cellular shades
Cellular shades , also known as honeycomb shades, are a window covering used to block or filter light and insulate windows to help save energy & reduce energy costs. The cell (honeycomb) size can vary. Cell shapes hold trapped air and create a barrier between the window surface and the room. Due to the unavailability of standardized tests, no ranking system exists, but they qualified for a 2011 US energy tax credit.[1]
Windows and doors make up for approximately one-third of a home’s total thermal loss, according to the Natural Resources Defense Council.[2] This applies to heat loss in winter as well as entry of undesired heat in summer. When air inside the room comes in contact with windows, it is cooled or warmed. By convection, this air then circulates around the room. Cell shapes in the blinds hold trapped air and create a barrier between the window surface and the room, thus lessening the transfer of heat.[1] Shades, however, provide only slight control of air infiltration.[3]
Cellular shades can be constructed as single cell, double cell, or triple cell shades. Single cell fabric has an R-Value between 0.28 and 0.44 (1.6 and 2.5 imperial), and double cell fabric has a metric R-value between 0.49 and 0.70 (2.8 and 4.0 imperial).[4] A 6 mm (¼”) thick single pane window has a metric R-value of 0.16 (0.91 imperial).[5]
Unlike window blinds, which are made of hard materials, cellular shades are made of a soft paper- or cloth-like material. Typically spun lace and bonded polyester are used, but other fabrics can be used during the manufacturing process.
In common with all blinds, cellular shades can reduce solar gain in summer[6] and provide room darkening or blackout for sleeping. Like most other window treatments, they are raised and lowered with a string. Cordless cellular shades are available to reduce the risk of strangulation for small children.[7] Or you can also have the option of lowering the top of the shade down, and/or the bottom of the shade up; commonly referred to as a Top-Down-Bottom-Up mechanism.
References
- ↑ 1.0 1.1 "Is it Worth It? Honeycomb Shades". This Old House.com. http://www.thisoldhouse.com/toh/photos/0,,20530758,00.html. Retrieved 2015-04-15.
- ↑ "Smarter Living: Energy Out the Window?". National Resources Defense Council. http://www.nrdc.org/living/energy/energy-out-window.asp. Retrieved 2015-04-14.
- ↑ "Energy-Efficient Window Treatments". http://energy.gov/energysaver/articles/energy-efficient-window-treatments. Retrieved 7 September 2015.
- ↑ "Prevent Heat Loss In Your Home: R-Value". Cellular Window Shades. http://cellularwindowshades.com/content/33-rvalue. Retrieved 2015-04-15.
- ↑ "R-values of Insulation and Other Building Materials". Architect's Technical Reference. http://www.archtoolbox.com/materials-systems/thermal-moisture-protection/rvalues.html. Retrieved 2015-04-15.
- ↑ "Residential, Today's Windows & How they Work". California Energy Commission. http://www.consumerenergycenter.org/residential/windows/todays_windows.html. Retrieved 2015-04-12.
- ↑ Safety Alert: Are Your Window Coverings Safe?, U.S. Consumer Product Safety Commission (retrieved 15 April 2015)
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