Wednesday, June 24, 2009

Beating the heat; and the cold.

Once again, this post is Sharon's fault. She posted a bit a couple days ago about facing a future with highly erratic fuel costs- making your choice of how to heat your home pretty significant. The subject came up because apparently, worry warts are already eagerly worrying about the unpredictable price of next winter's fuel.

In the comments, the idea of putting bubble wrap on your windows as a way to decrease heat loss came up- and it turns out Sharon's family already does this.

I may have a better trick; at any rate it's certainly a different one, useful in other situations.

We cover our windows- very tightly- with "space blankets" during extreme weather- either hot (blanket outside) or cold (blanket inside). (Our definition of extreme- colder than -10°F/-23°C, or hotter than 100°F/38°C.)

We use the very inexpensive ones inside; the ones that are just a piece of mylar with aluminum vapor deposited on one side- those can run as cheap as $2.50 for a 4 foot x 8 foot piece. The ones with a more complex construction and tough fiber reinforcement run around $12, but if it's going to be subject to wind, you'll need it.

The outdoor ones come with grommets installed- you can position them over any window that is letting sunlight into the house (shiny side out!), and drastically cut your heat gain.

The indoor ones are fragile, and tear easily- handling them is a job for an adult, or you'll run through them quickly. Well handled though, one blanket can easily last 5 years. A torn piece can be pretty easily mended with any kind of tape, even Scotch.

What we do is put 1" long pieces of self- adhesive velcro tape on the inside of the window frame. Clean the frame well beforehand; finishing with isopropyl alcohol; this is permanent. We usually put the hook part on the window frame, and the pile on the mylar (less abrasive in storage.)

Then, put the mating pieces to the velcro on top of those in place on the window frames- and expose the adhesive. You need to determine which side of the blanket has the aluminum on it- for two reasons. That's the side you want inside, for best reflection; and - the velcro tape will not stick to the aluminized side- it'll just strip the aluminum off, and you'll have to do it over. (I would know.)

Have a good idea of how your piece is going to fit. (If it needs to be cut, we usually try to cut it after this next step; more efficient; leaving bigger pieces for other windows.) Start in any convenient corner, and press a corner of the blanket onto the sticky tape; leaving a good margin of blanket to cover the window thoroughly, including cracks.

Press it in hard; hold your thumb on it for 30 seconds or so to heat it a little. Then; gently stretch the blanket to the next corner, and repeat. You want the blanket to be stretched quite taught when you are done. The velcro is somewhat forgiving- you don't have to match pile and hooks exactly, so you can increase the stretch when you are re-mounting the blanket on the window. Don't pull it too tight during the initial fitting, or you can pull the bottom velcro off the window frame.

Leave the blanket in place for 24 hours if possible, to allow the adhesive plenty of time to really set up. When removing the blanket, you need to work your fingers in between each pair of velcro tabs- just trying to pull on the blanket to get a tab to let loose is guaranteed to tear the blanket eventually. Find the junction between the hook and the pile pieces with your finger nail, then wiggle your finger between- no stress on any of the components.

This REALLY cuts the heat loss from windows- when we put them up in winter, it feels like standing in front of a stove when it goes up. When the blanket is reasonably taught, it will act to cut convection and conduction losses through the glass, acting as another storm window. It doesn't have to be perfect to make a big difference. If you have a very drafty window, you can increase the effectiveness of the blanket by adding velcro tabs in between the corners, holding it down tighter.

And, of course, it cuts radiative loss by around 80%. You can easily make that 90% if you want to- by using a double layer of mylar.

Another huge benefit- when the space blankets go up- your winter house becomes much brighter inside. It also makes the house feel smaller- which can be cozy in a cold snap. I should point out- here in the Little House, our windows do not have curtains or blinds. We want to see the world- and there's no one to peek in. Doing this on windows with accoutrements is liable to be a little more tricky; but still doable.

We take the blankets down when it's sunny- to let the sun and heat in; and to help prevent cabin fever. It's easy to release the velcro; fold the blanket and put it into a 1 gallon ziplock bag; and keep it next to its window.

For summer- label each bag, and store away with the winter hats and gloves.

I think this is very likely to be more effective than the bubble wrap, which cuts no radiative loss to speak of, and varying amounts of convective and conductive.

Of course- if you use BOTH - you could probably cut your fuel needs drastically!


The other problem with bubble wrap of course, is that 13,341 children were murdered by their parents last year for chronic bubble wrap popping. They just can't help it, it seems. The little kids love to jump on it, and the big kids love to pop it between their fingers. Parents sometimes just snap.


Rosa said...

Hmmm. . .
How do you think this might work on the walls of a free standing greenhouse in early spring? ( it's aluminium framed and poly carbinate (sp?) walls)
This was my first year with a greenhouse and the length of time I had to use a heater was a shocker.
I had thought of using solar power but the heater pulls 1500 watts!

Rosa said...

Oh, I forgot to say that I live on the Canadian prairies. It gets mighty cold up here. :)

Greenpa said...

Rosa- I think something like this is very much worth a try. We get chilly here too, though I'm sure we can't compete. Down to -36F last winter.

We have a commercial greenhouse; we pretend we make a living with it. It's earth sheltered- which I highly recommend. Expensive up front- cheap in the long run.

The thing about it with your greenhouse- I think you'd want to get out to it early every morning and take the mylar down, so your solar gain can start working. You might get really tired of always getting up just after dawn! And putting it to bed, every night.

Greenhouse supply places carry greenhouse blankets on rollers- pricey, but. I'm pretty sure some of them have a reflective inner surface.

e4 said...

You don't have trouble with the velcro adhesive getting warm and gooey and falling off on those really hot days? We ran into that with our (admittedly different) setup:

Chile said...

We use the foil-backed insulation that has bubblewrap in the middle. It works well at keeping the summer heat out.

Greenpa said...

r4 - ah; neglected to mention, we don't use velcro on outside setups- but some kind of nail/string arrangement; easy on a log cabin. It IS nice to see out; the effect of the opaque blanket is that you're inside a cool cave- which can be nice, too.

Chile- you know, thinking back- I'm pretty sure we started using "space blankets"- before bubble wrap was invented. gasp. Geezer moment there.

One advantage the space blanket still retains is the extreme compressibility- it can be stored in a very small space. Otherwise, you're likely ahead of the game.

Hickchick said...

Cool, umm I mean hot idea. I'm going to save that one for AFTER our move to the country though-we are already the trashy neighbors in this suburb. :) kris

jewishfarmer said...

This is a good idea. For us, the advantage of the bubble wrap is the light transmission - making my house darker in the winter (yes, I know, more reflected light, but it isn't the same as *sun* however faint ;-)) isn't high on the agenda - the bubble wrap stapled into wooden frames also has the advantage of being something I put in once a winter on most of our windows (I don't use it on all of our windows - say, the big bay one in the LR though which we watch the birds - those get window quilts and styrofoam insulation pop-ins. But yes, I think that's a good strategy if the light loss doesn't matter.

Actually, I wonder if the heavier space blankets could be successfully sewn in as a liner to existing window quilts for aesthetic purposes?


Greenpa said...

Sharon- sorry I wasn't clear- we take them down during the day! Exactly; dark is not what you need in the winter. When the sun comes up, and it's -25°F. we take down the blanket on the East window. (If it's warmed up; we'll just take them all down)

My other problem with bubble wrap is not being able to see out- I'm addicted to it. Having bubble wrap on the windows all winter, for me, would be the same as having closed curtains over them-

Hank Roberts said...

Hey, y'all should be reading Tobis:

Saturday, June 27, 2009
Long Time Coming

" ... Most of us don't have a sustainability mindset.

Those few that think they do, mostly don't. The green movement have a Luddite view, a romantic view perhaps workable on a planet with a tenth of its present population. They are, I think, good people with much to teach us, but they aren't really facing up to the scale of the problem any more than most other people are, and their culture is actively suspicious of quantitative thinking. So much as I love greenies, as much as I hope the agrarian ideal eventually pans out, this isn't the time for it. We have big, collective problems to solve and we need a big, collective way of thinking about it. And not even a Woody Guthrie-esque "one big union" is big enough. Big government, big business, these are part of the solution.

The press isn't giving us the vocabulary to think about our circumstances...."

kathy Harrison said...

My husband got a hold of an old solar pool cover. He cut a double layer to fit the north and west walls of our greenhouse. It keeps the interior warm enough that we never have frozen ground, even in January (Western Mass). While we don't get a lot of growth in the dead of winter, we are able to eat salads out of it for 10 months of the year with no additional heat. If I had a bigger greenhouse, I would keep the chickens in there.

Lisa Carroll-Lee said...

These are great ideas. We have a wall of west facing windows that soak up crazy heat. We've put solar fabric awnings outside and solar shades inside. May have to add space blankets too!

Anonymous said...

I'm sure the space blankets are a much better idea than mine...which is tin foil taped to the windows. Tacky, low tech, but effective. I do take pity on my neighbors and put the less shiny side out though.

Our biggest heat loss and gain is by far our windows. I got through most of the winter last year with the temp at between 50 and 56 in here, but I'd rather be a little warmer (so I can continue growing things during the winter like mushrooms and lettuce) so if we end up not getting a super efficient wood stove, we'll probably do the bubble wrap. I doubt I'll do the sliding glass door which actually is probably the best insulated window in our house, but the rest of them quite frankly may as well be open for as well as they keep the drafts out.

I will get a couple more emergency blankets and try them in rooms where the light coming in is not a mental necessity and see if it helps.


Anonymous said...

I am looking for the outside Window Blankets. Please tell me where to find them with the gromets...
Thanks what a blessing you are for the rest of us. We have a 2 story hom pre-bought prior to us getting smart. We are now re-doing and re-thinging our though process and well it's very hot upstairs in the summer with no AC. Hopin this will help cool it down by reducing the heat aspect.
Jeanne, NC

warm said...

Novel ways to beat the climate ... thanks for sharing.

Unknown said...