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Old 11-11-11, 11:03 AM   #1
Join Date: Sep 2008
Location: SE Wisconsin
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Default Poorman's Thermal Shade experiment

Last night, I was especially cold.

My thermostat said it was 68 degrees, but it sure didn't feel like it.

The reason why is that I have a fair number of windows. Even though the house has newer, modern-type double-pane windows, they still do NOT insulate the way a stud-wall does.

In fact, windows have what I like to call the "Cold-Rays" effect.

Of course there is no such thing as "cold-rays". Scientifically, there isn't even such a thing as cold, just lack of heat energy.

Anyone familiar with radiant heat can tell you that it warms in straight lines - the heat shoots at you, hits you, and keeps you warm. However, we are constantly surrounded by objects that have some amount of heat in them. We give off heat, they give off heat, and as long as everything averages out, we feel fairly cozy.

The problem is that a cold window will radiate out a LACK of heat. Even if the window has proper weatherstripping, and there's no air movement, it will still feel "drafty" near the window.

What's really needed is something to stop the "cold-rays", especially at night when it's colder, and you really don't need the view out the window, or the natural lighting.

A while back, I got some scrap packing material from a friend of mine, who works as a manager at a big box store distribution warehouse. The get goods in at the warehouse wrapped in sort of a thin bubble-wrap with an aluminum or mylar silver surface on the one side.

I had a big sheet of this stuff folded up behind my garage, so I went and got some of it, and cut it down to size to fit my window.

I already had a plain accordian blind for the window. Here's what that looks like from outside at night.

The accordian blind is "inside" the window. That is, it is sunken in from flush with the wall. By putting the bubble-warp OVER the window, I now have layers. The accordian blind is completely hidden, but still usable, and when it is down, it prevents anyone from seeing bubble-wrap from the street. (Makes it look pretty)

Here's my upstairs bedroom window from inside.

And with the blind down.

And with recycled packaging material over the top.

I just used two pieces of tape to attach the packing material over the top of the window.

Subjectively, it felt much warmer near the window right away, but I know all you guys like to get scientific, so let's pull out the infrared point and shoot thermometer!

Here's the bare window. It was hard to get a reading, because the thermometer would either shoot THROUGH the window glass, or reflect back at other things in the room. Finally, I settled on pointing at the back part of the metal window latch - a chilly 54 degrees!

Next, I dropped the accordian blind. It has nearly no (conductive) insulation qualities, but it is designed to block light. Sunlight is radiant energy, so I would assume even this simple blind would be fairly effective at blocking the "cold-rays"!

Sure enough, measuring with the blind down, it was nearly 68 degrees!

This is the upstairs bedroom. Even though the house thermostat was set to 68, the upstairs air temperature tends to be a tad higher, as warm air rises up the staircase. I may have been running my wood stove at the time as well.

Getting a good reading with the radiant bubble wrap over the window was a little harder. The shiny side would just reflect to read from the inside of the room, or even my skin temperature if I was square on to it. I finally got an angle that I felt was a legitemate reading.

Just as a point of reference, I also got the temperature of the exterior wall about a foot over from the window.

I also put one hand between the bubble wrap and accordian blind, and the other on the room side of the bubble wrap. Subjectively, my hand on the inside of the bubble wrap felt much warmer.

Also, in terms of looks, from the outside of the house, the accordian blind blocks the view of the ugly bubble-wrap.

The bubble-wrap also blocks most of the light. In the photo, how much light is at the window is a bit of an optical illusion. It's a long exposure, just to get the image (which also makes it blurry!)

My point is that you see a typical blind, not weird big box store packaging. I have been in low-rent neighborhoods where peoples apartments don't come with blinds, so they just hang up sheets and blankets for privacy and comfort. It looks AWEFUL. I think that's one of those things covered in some neighborhood associations now.

From the inside, the astheics leave much to be desired, unless you like living in a bad 1970's Sci-Fi movie.

I would be rather easy to sew up a cloth cover with a material that would match or complement the room. A weighted rod could hold the bottom of the material, and then some light cord could be used to roll the blind up during the day.

If a person wanted to get extra-fancy, they could try some corner magnets or strip magnets down the side to hold the blind air-tight to the face of the window to prevent any convective air currents.

All in all, I felt much cozier for an investment of 10 minutes of work and no materials cost.


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blind, bubble-wrap, heat, radiant, window

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