People buy different products at different times of year. People buy products that shade well in the summer, and they buy products that insulate well in the winter. In order to help make the best buying decision, I will try to explain how window coverings, namely blinds and shadings really work.
Insulation vs. Shading
Window coverings do not all perform all the same function. If we are talking about heat transfer, they do different things and the most simple way to explain it is using the words INSULATION and SHADING.
Insulation– Simply put, insulation means creating a barrier between two different air masses. If you have an insulating layer in your window, you can stop the warm or the cold air from transferring from one side of the window to the other. So, to explain, imagine a hot summer Reno day. If the temperature outside is 100 degrees, you will need an actual barrier on that window to prevent an equalization of temperatures. You have a R-rating ( a measure of insulation ) in your walls of at least R-19 and yet most of the window coverings have an average R-value of R-2 or so. Clearly, if you are trying to keep your expensive cool air inside your house, you need a better barrier. The same is true when trying to keep your also expensive heat in the house during our cold Reno or Tahoe winters. Some window shadings have R-values over R-7, which is just about as effective as you can be in stopping the exchange of air temperatures.
Shading- The other main way to stop heat gain is via shading. This is a concept that is easy to illustrate. When you are out in the sun, and you want to cool down, don’t you find shade? This is because the thing blocking the sun is keeping the actual energy from the sun from hitting on you and radiating the suns energy off of you. In your house it is the same thing. If you can stop the sun’s rays at your window, you keep the sun’s energy from entering your home and heating up all the things inside your house. So, your furniture, your carpet and anything else that the sun normally hits will not heat up and therefore will not provide heat gain. For the most part, anything that is not sheer will shade at roughly the same rate, though the more opaque (blackout) that a product is, the better it will shade.
Herein lies the rub. A blind or a shade will probably not suit all your needs. The single most popular product in Reno or Tahoe right now is a 2″ faux wood blind. This product does shade very well, but it has serious flaws in its insulative qualities. The following blog post will discuss how to select what is best for you.