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Shading (Blinds, Curtains, Awnings, etc.)

We've got a lot of options when it comes to using shading in order to limit heat flow in and out of the house, the main ones being blinds, curtains, and awnings.

The first thing that came up when researching blinds is the R-value that certain blinds will afford to us, which is a measure of how resistant a material is to heat flow. Basically, the higher the number, the better a material is at limiting heat flow. Insulation has a value of about 40, while windows are 0.9~3.0. Shades can increase the R-value of a window by 62%. The two best types of shades are cellular shades, which are basically hexagonal tubes stacked on top of each other, and insulated Roman shades, with blinds going anywhere from $20-100 for a single window set.

Curtains made of a thermal material can also help to block a lot of sun. There is a material called temptrol which can be easily sewn and cut and is apparently quite good for making thermal curtains. They block 100% of light and 95% of heat flow, but still allow airflow to keep things from getting stuffy. Cheaper curtains can still cool a room by about 5 degrees and can cost $10-20 for a window.

The last option that I examined were awnings, which can be incredibly helpful in a structure with windows facing west or south. Depending on the direction, an awning can keep 55-75% of heat from entering a set of windows and reduce indoor temperatures from 8-15 degrees. With venting, it is also possible to allow air circulation and dissipate heat, which can also be accomplished by picking a color that reflects instead of absorbs light.

If we can figure out what trade offs we're willing to make between price and efficiency, there is a lot of energy to be saved with these passive shading techniques.


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