Wednesday, December 8, 2010

A blanket experiment!

After suffering through the first real cold blast of the pre-winter season and feeling pretty cold, I began to look at any area of my house that might still be poorly insulated. I had done all the routine work of making sure windows and doors were properly weather-stripped and had even gone to the extra effort of installing plastic over some of the windows (3M insulation kit). Even my sole bedroom window got this treatment. However, when the mercury got down to the twenties recently, it still felt pretty cold in there by next morning. The cold seemed to be coming from a large sliding glass door that lead to a balcony which felt cold to the touch. Ah, I thought, perhaps this is part of the problem. Now, I did not want to go to the expense of covering it with the 3M plastic, but though that perhaps some improvising could still be in order. I had extra blankets stored in the basement and thought it might be interesting to see if they could provide a measurable amount of protection against the cold. Also, since I had a precise temperature recording device in that room, I would be able to quantify any improvements in ambient room temperature during an overnight period of time.

The area to be covered measured about 69 by 79 inches. I selected an old polyester blanket that was almost a perfect fit though it left a few inches open at the bottom.

Surprisingly, with the use of a few push tacks it went up very quickly (ten minutes) and did not actually look all that bad once I re-closed the venetian blinds. Also, the light coming through the blanket was more than sufficient to light the bedroom during the day time. It might be important to note that this window face the north. If you have a south facing window, then you might want to keep it cleared on sunny days when the sun is shining in. This job was so easy that I also decided to throw up a blanket over the sliding glass doors in the dining area.

The next morning disclosed an interesting conundrum. While I felt warmer on arising, I discovered that the temperature reading of the room was almost a full degree below the previous reading. Yet, even though the overnight temperature was very close to the reading the night before (18F versus 19.5F this morning) I noticed that the kilowatt hours burned yesterday versus today was lower (23 KWh versus 19 KWh)! But wait! If you examine the two charts above (last five days, outside temps on top, inside on the bottom) take note of the area I indicate with the 'notice curves' label. The slide of outdoor temperatures from about 30F to a morning low in the teens was much later in the overnight hours than it was this morning. That could explain the difference in less energy expended for the furnace as it may not have had to work as hard. Still the smoothness of the temperature profile this morning is interesting.

So, does this technique of covering large glass areas with a blanket have a measurable effect? I guess the jury is still out on that one. I think I’ll leave both doors covered for a while to see if I can get additional data. Stay tuned to this channel!

Update: While I did keep the cold out in a greater degree than I would have with no covering, I'd have to still say I would take a pass on doing that again. Too much of a hassle. 

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