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bennelson 11-11-11 11:03 AM

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.

WD-40 11-11-11 01:49 PM

I had similar thoughts.
Get emergency foil blankets ( Econo Emergency Foil Blanket ) and find a way to roll them up like roller blinds, or maybe if you have roller blinds already then spray glue the foil to them.

Xringer 11-11-11 02:57 PM

Deadly-Cold Rays
I had a serious problem with Deadly-Cold Rays last winter.
My PC is right next to a pair of nice tight replacement windows..
When it's cold out, I can feel the Cold-Rays hitting and penetrating into left my shoulder.
Since I sleep on my left side, that's a very important shoulder.. :eek:

So, I had some scrap CoroPlas that I cut to (almost) the width of the windows.
I stick them up there at night, when it gets cold. They stopped the Cold-Rays, dead in their tracks!

The blue Cold-Ray blocker also works nicely as a sun blocker.
In the early AM, the sun lights up my LCD monitor & keyboard way too much.
Not only does the blue one block the sun, but it becomes nice and WARM!
My left shoulder is gently warmed by it's radiant heat.. :thumbup:

Where can you get coroplas? During election season, you can harvest
many square yards of coro-political signs from the local front yards,
(do this only at 2AM) or call up your local candidates and tell them
you are a big supporter, and want two dozen really large signs.. :cool:

sparkchaser 11-14-11 07:00 PM

Nice! I was thinking about that coroplast harvesting thing myself! I hate seeing all those political signs go to waste! I have some windows that would work well in, such as the bathrooms which already have privacy glass, so the white coroplast still lets in light but adds insulation! Hey, election day was just last week! Time to check for some signage!

Xringer 11-14-11 09:01 PM

I found out about coroplas years ago..
SPA3D pictures by Xringer - Photobucket
I gave up on Balsa-wood and flew nothing but SPADs (coroplas and aluminum). They are tough!

Piwoslaw 02-01-12 02:57 PM

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I've noticed that the cold-rays from my windows are less harsh when the roller blinds are down, so I waited for the really cold weather to come in to test it. Armed with an IR thermometer I did some measuring.
The temperature of the room was 18C, while it was -19C outside, so that's a 37 degree (C) differential across the double pane window! I measured the surface of the window's glass to be at 11.8C with the blind rolled up (open). When down, the blind's surface temperature was 14.5C, while the glass underneath was only 8.8C. I went outside to measure the temps of the two windows, but there was no difference between them (around -16C).

I'll try some bubblewrap with aluminum foil on one side tomorrow and see the difference that makes, but there are slim chances that the rest of my housemates will want to look at a window ornament like that:rolleyes:

Piwoslaw 02-02-12 01:38 PM

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Originally Posted by Piwoslaw (Post 19491)
I'll try some bubblewrap with aluminum foil on one side tomorrow and see the difference that makes, but there are slim chances that the rest of my housemates will want to look at a window ornament like that:rolleyes:

It turned out that my windows are larger than the width of the alu-bubble-wrap I have, and since I didn't want to cut just for this experiment, I used the following set-up:
Not purdy, but still gets the job done. Without the bubblewrap the temperature of the roller blinds was 13.5C and the glass underneath was 4.7C. With the bubblewrap up (alu side facing the room) those temps were 10.8C and 4C, resp. The surface of the bubblewrap was 16.5-17C (warmer than the walls in the room!!) and I could feel the heat bouncing off of it. I could also feel the cold air pouring out from behind the bubblewrap. Making the set-up just the right size, and sealed all around the perimeter, would do wonders:D
The outdoor temperature was around -22C during the test.

I just remembered that I once saw (in California in the mid-2000's) a house with roller blinds made out of something reflective. They seemed like a good idea, both as thermal insulation in the winter and as a sunshade in the summer. I haven't seen any houses with them since then. Maybe I could retrofit my blinds?

bennelson 02-02-12 02:31 PM

I like the idea of retroftting the roller blinds with a radiant material.

Something like space blankets or mylar is very thin, and would roll up fine.

Put the silver side on the INSIDE, other wise the outside would reflect car lights at night, not look as attractive for the neighborhood, etc.

Now if the issue was keeping HEAT OUT in the summer, you would want the silver on the outside. :thumbup:

Xringer 02-02-12 05:26 PM

I've been looking for some nice Eco-blinds.. Not like these,

But reflective silver on the top, and absorption black on the bottom.. :)

Close them with the silver to the inside during the winter, and to the outside during the summer.. :D

Anyone see anything like this on the web yet??

bennelson 02-02-12 09:18 PM

Dang~! Two-tone blinds! Genius!

I love ideas where I go "why didn't I think of that!?"

Right now, I am really resisting the urge to get out a can of paint and just going at my plain wood blinds!

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