Tents as space reducers for heating

This idea is related to the thread Adding Heating Zones to the House where I talked of making it so rooms in the house can be curtained off for heating issues, I have been checking my tents for set up in the house if needed. Cutting the amount of space you need to heat can be VERY useful, and curtains and tents can partition space nicely.

I'm living in a rental, a cheap tract house that the heating involves electricity, in an area that's known for losing power (especially in ice storms,) and they have been predicting rolling blackouts for the winter. It's a cheap tract house, with insulation issues at best, I fixed a bunch of them last year, but the structure of this house is just badly built, there's a limit to what I can do. So I'm making sure that I have a plan ready to implement if I need it in the winter.

Tents can be a great size for sleeping in, and tend to stay warm with body heat. Mylar sheets or light blankets or can be tossed over them (watch the weight!) to insulate them further. Mylar can be the cheap little space blankets (taped together if needed) or it can be bought in rolls (I recommend buying them NOW if you are likely to need them.) Type "mylar rolls" into any search engine, lots of hits. Lightweight blankets are probably available second hand, make sure to wash them, and if you are sure you will be using them, you might drape them over the tent now when you are testing it (see below) and use safety pins to take pleats in it to make it fit well. Then if you need it, it will drop into place easily.

It's currently late July, and tents are easily available, and on sale for the season ending. They are also showing up in thrift stores as people buy new ones, check the poles carefully after buying it if you buy used. Bad fiberglass poles are not a deal breaker for used tents, they are easy to replace. Tent pole repair kits are worth buying for any tent. Make sure the pole diameter matches if you have to buy a repair kit.

If you want to consider this, I suggest:
>>> Measure your spaces, if you move what you can, what are the biggest dimensions you can use in each direction? Take good notes!

>>> Look for tents that will fit into your space. Ideally you want space left to walk around it. Putting it up WILL be trickier without walking space. Tents with a hexagon footprint fit square spaces weird, make sure you leave extra room if you have a hexagon tent.

>>> When you get one, I REALLY recommend learning how to work it over the summer, before you are in need of it and learning things the hard way. Put it up outside, where you have lots of room. Look at how it goes up, where it can flex or not. When using a pop up style tent, the joints can NOT be flexed in odd angles, they WILL break. Fiberglass poles are more forgiving, but it's still worth having a repair kit on hand.  

>>> When using a tent with fiberglass poles that hook together, you can open joints up, feed the poles through, and hook them back up in order to have space to thread it in the house. If you will need to do that, practice it out in the yard. In the house is a lousy place to learn to do something tricky. I'm a big fan of practicing skills when it's easy, so you are already competent when you need them. In the dark, when it's cold, with crying kids is a bad time to learn anything.

>>> A pop up type tent is great in that you don't have the pole problem and they set up in their own footprint. They do not flex, and you cannot change their size though. They go up quickly and easily. Buying them second hand is iffy, they tend to be there due to broken joints, and the joints are not easy to fix. The twist up kid tents might be worth looking at!

>>> If you have fiberglass poles you can make the space smaller by folding one or two joints of each pole out of the way and hooking it there. It will make the tent baggy, and the excess fabric will need tucking and adjusting, but it will make the ceiling lower so less space needs heating.

>>> Open flame can NOT be used to heat a tent, they catch fire AMAZINGLY FAST! What CAN be done for heat includes:

~~~ Insulate. See above about blankets or mylar. The advantage to having a tent indoors is rain and wind are not a problem, so you can get away with things you would not be able to if you were camping. Watch weight on the top, if you need to, consider running stabilizing lines from the tent to furniture or unused doorknobs.  I keep a roll each of mason's twine and clothesline with my tents, as well as things like spring type clothespins, safety pins of all sizes, and small C clamps. Gives me lots of options for doing what I need to. Also consider insulating under it, having extra blankets or a rug ready to use saves a lot of heat if your floors are cold. Ideally you'd sleep up off the floor, this is why beds were invented, but that may be problematic to design. Consider it if you can. If it's going to be a long bad storm, hauling mattresses off the beds might be worth your time. Blow-up beds have air in them and never heat up well, if you plan to use one, have lots of extra padding between you and it, as they will pull the heat out of you all night. If things are bad enough and it goes on long enough, dump all the clothes you own in the tent and sleep on/under them.

~~~ Warm bedding. Seems obvious, but I am amazed by how many people own only one or two blankets, assuming the house heat will always be there. Second hand stores are full of blankets this time of year, wash them well, and if you need storage space for them right now, put them under mattress on your bed. Flannel sheets are really nice too! Those tend to show up second hand also, and they also can fold flat and store under your mattress.

~~~ Body heat. It's amazing how much heat your body gives off. The more people in the tent, the higher the heat goes. If you are doing something like putting little kids in a tent of their own, it might be a good idea to have the adults hang out in the tent with the kids for a while to warm it up before going to their own tent. Better yet is to have everyone sleep in one tent so body heat is shared. Dogs and cats are warm, as are all livestock but sharing a tent with goats might not be pleasant!

~~~ Bring in warm items. If you cook dinner on a fire or cooker of some sort, or at a neighbor's or even in the kitchen if you are doing this just to cut your bills, heat an extra pan or kettle of water to bring into the tent, if not, bring your food into the tent to add it's warmth as you eat it. If for any reason there is something warm that can be brought in, do it. If you have to drive anywhere, put something that will hold heat near a heater vent of the car and warm it up, put it in the tent immediately upon arrival.

~~~ Catalytic heaters Wikipedia about them: Catalytic_heater It's a chemical reaction, not a fire, they are safe for tents and trailers. Look for them online under camping equipment. Hand warmers are a type of catalytic heater. Make sure if you are going to use one of these you have the fuel it needs, and me being me, I'd say buy it now. I have two catalytic heaters from camping, and have the fuel I need stocked. If you have one that needs flame lighting, do it OUTSIDE, not in the house at ALL, then bring it in when it's running. Having a carbon monoxide alarm (sold by the smoke alarms) is wise, as is having a smoke alarm. Being too safe is better than not safe enough.

What did I forget to mention? Please tell us! I am getting all of this straight right now,and would LOVE to know if I'm missing something.

One up on your tent idea, which is still essentially heating a whole room but with extra inconvenience for moving around.



This is a traditional style of heated table in Japan. The rooms were typically cold, but the heated table makes for a comfortable space for meals, sitting and socialising, or napping. You can buy (expensive!) electric heater kits to install on a low table. I imagine there would be all sorts of issues of temperature regulation, fire safety, and not burning kids legs to get right.

My two-man classic green Eureka Timberline tent, is the perfect size for a standard double bed mattress. If you really need to just heat your sleeping space. Eureka Timerbline Tent  Looks like they still make and sell this model that I bought in 1995. It's a great tent with aluminum poles, which are less likely to break.

Pearl sort of covered this, but hot water bottles are really useful for safely heating your bed. Even if the power is off, if you can heat water outside on a camp stove or regular fire. If you do have that fire, position some rocks to absorb heat and move them into the tent using hot pads - some can get hot enough to melt things you don't want melted, so use caution.

I'll reinforce the idea of having good insulation *under* you as well as on top. Closed cell camping mattresses are good for that, but even multiple layers of corrugated cardboard can slow down heat transfer and make a difference.

If you look at old pictures of "cupboard beds" and beds with drapes all around them, there's a reason for them, and containing body heat was it! Very few people slept alone if you look back even 150 years.

Yes - it's *really* hard to be thinking along these lines during a heat wave!

Under insulation is super important, yes.

I've been using my camping hammock in this heat. It comes with an underquilt, slung beneath the hammock. Without it gets cold beneath, because the sleeping bag wadding gets squashed flat.

Michael Cox wrote:
This is a traditional style of heated table in Japan. The rooms were typically cold, but the heated table makes for a comfortable space for meals, sitting and socialising, or napping.

I have something similar like that worked into our diner table, which would be in the only sunny room this house has in a storm. That room got rods for curtains installed the other day (see the linked thread above) and would be the daytime hangout space, with a low ceiling tent that can be shared being sleeping space in another room.  

I was alone here when the bad ice storm a few years ago hit, and learned where all the flaws are in the house construction, and am working on mitigating all I can. One of the main problems was air leaks in the house, it has no vapor barrier or house wrap. Heating any full sized room was a waste of time, the wind was whipping through the walls. I had ice in the house. I stopped as much of that I could, but without power this place gets COLD. the bedrooms are the worst here.

I've lived in a string of very old and drafty houses. It is amazing what you can achieve just by carefully going around plugging gaps. I found that slightly damp kitchen paper towels worked well, poked into gaps around window frames and the like using a slim blade. They still allow windows to open when summer comes, but drastically reduce the drafts. Even if you did this in just one room, that you intend to keep warmer, you could be a big difference.

It may be worth mentioning for people that aren't Pearl and don't have all their ducks in a row and so, get caught off guard and aren't ready ahead of time.  It's very easy to makeshift a tent.  Cold isn't so much an issue when you are up moving around and busy, you can simply dress warm and you'll be fine in all but the coldest weather.  When you are tired or trying to sleep, you get cold much more quickly.  A very simple makeshift bed is your kitchen table in an emergency, if you have a table 6' or so long.  If not, you can put the chairs out from the table ends and extend it.  Insulating a table is super easy.  Pile on your mattress and couch cushions, extra pillows, extra blankets, towels, or clothes on top.  Take several blankets, put them down to lie on, some to lie under, and drape more over the table and down to the floor to make a cozy nest.  Lots of ways to use other furniture if your family won't fit under the table.  Four chairs will hold up your box spring, and you can insulate just as you did your table.  Once you start thinking that direction, you'll notice all sorts of ways to make a nest.    

Michael Cox wrote:drastically reduce the drafts. Even if you did this in just one room, that you intend to keep warmer, you could be a big difference.

That's what I did last year. And made insulated shutters that go over the worst offending windows, that I have been covering with heavy duty plastic every winter since we moved in. Most of the problems here are not visible, I put thin sheets of styrofoam on the walls in the worst places, and covered them with linoleum, as those are what I had. Made a world of difference. Between that and straightening up the insulation in the attic I cut the electric bill by 1/3 last winter and increased the comfort level a LOT. I didn't have to wear a coat in the house all winter.  

This is a story of a toasty warm onion. A few years ago I found myself moving into the man cave. Actually, it was originally a woman cave. They built it to house a boat in half & as a party room in the other half. It was nice enough (carpet & paneling) but rather crude & full of air leaks. No air conditioner or heater. Very little insulation in the walls. None in the ceiling because some squirrels got up there during the years it was idle & made a huge mess. When I moved in the ceiling had already been ripped out but never repaired. Metal roof. In the summer. The first thing I had to do was insulate the ceiling & add ceiling panels so I didn't fry in the heat. Since that was a very messy job I decided to set up a tent inside. Also sealed air/bug/bird/squirrel/snake leaks in the process.

Summer temps weren't bad with open windows & a fan. Then winter came. About 5000 feet altitude in the northern-ish Smoky mountains. With a concrete floor. No padding under the thin carpet. I don't do winter well. No way was my tiny space heater going to keep it warm enough. This is where it gets oniony. When I moved out of the previous house it wasn't possible to remove my mattress from upstairs since the banister had been repaired. It was a king sized pillow top that we originally barely got upstairs without the banister. So I cut the pillow top part off & saved the foam bits from inside. That fit inside the tent perfectly & was very comfortable. When winter arrived I added some more foam & a reflective windshield screen underneath the tent. Then added aluminized mylar sheeting to the outside of the tent underneath the rain cover. Added mylar sheeting to the nearby walls too. Placed boxes full of stuff (thermal mass) between the tent & the walls. Used a zero degree sleeping bag with several blankets available. This is also when I discovered flannel sheets. Why didn't someone tell me about flannels sheets when I was in college in MN living in an unheated basement? That would have been a game changer. Add one cat & sleeping in the onion was always warm. Even those times when the room itself was way too cold.

A couple other things helped keep the living space warm. The entire side of the building had windows so I made some 2x2 frames & added some clear plastic pieces to essentially turn them into double paned windows. Filled a 55 gallon drum with water & used a small aquarium heater to heat that water. Every time I finished a gallon of milk it was filled with water & placed wherever it would fit. Water is excellent thermal mass. Cast iron cookware was placed on top of the space heater to help radiate the heat.

I miss the onion. Thinking of setting it up again this winter. Won't need all the oniony parts since I have a fireplace now. Also better insulation, better heater, & milder winter. It was just so cozy!

The ornate canopy beds of Victorian times were more than ostentation -- they were tents with a roof and bedcurtain sides used to retain a pocket of warmth in drafty old buildings.

Come to think of it, a canopy bed could also be a pocket of cool air on the rare occasions we use our portable air conditioner. It would take a fraction of the energy needed to cool the whole bedroom to a sleeping temperature. Hmmm...

Think of a twin/full bunkbed.

https://www.wayfair.com/baby-kids/pdp/mack-milo-simoneau-twin-over-full-metal-standard-bunk-bed-w005404851.html?piid=1188209176

Now, instead of a twin sized mattress on the top, place a hard board there, you can use it as shelving.  Drape some heavy blanket over the edge of that top bunk, edge tucked under the top board, much like how the Japanese heated table works.  You're basically making winter curtains for the lower bunk.  

Then add this to the lower bunk...

https://www.amazon.com/Beautyrest-Mattress-Technology-5-Setting-Controller/dp/B0068DKWWY

Then use a decently warm top blanket or comforter, and you'll do fine in some pretty deep cold.  This is the same mattress pad heater that I've been using for 6 years, except I have a king.  The heated mattress pad is a joy, but when the room is particularly cold, you'll still feel it in your face.  So the bed "curtains" help to make a pocket of heated air, from your own warmed breath and the escaped heat from the mattress pad.   It has 5 heat settings, each one adding about 25 watts each.  I've never gone higher than 3, and I imagine I could sleep outside on 5 and a decent winter comforter.

Douglas Alpenstock wrote:Come to think of it, a canopy bed could also be a pocket of cool air on the rare occasions we use our portable air conditioner. It would take a fraction of the energy needed to cool the whole bedroom to a sleeping temperature. Hmmm...

Ever heard of a ChiliCube? It's like a heated mattress pad, but it's a cooling unit.

https://www.amazon.com/ChiliPad-Cube-2-0-Temperature-Enhancement/dp/B07GT9MYRW/

Creighton Samuels wrote:

This is the same mattress pad heater that I've been using for 6 years

I use a mattress warmer but normally I turn it on for ~1 hour before bed and then turn it off as I get in (it conveniently has a built-in 1 hour timer!) However, it's a bit useless in a black-out which can easily happen in my area in any storm due to all the trees around us. Luckily, we do have two wood burning stoves. They aren't anywhere near as efficient as an RMH, but if we're desperate, one is downstairs in a room that's easy to isolate, although fairly large. The one upstairs can't easily be isolated at all.  Our weather only occasionally gets ridiculously cold, so I'd be inclined to do the "hot rock" trick - heating them on top of the woodstove then tucking them into the bed for an hour.

I admit electricity is darned convenient and in my province not nearly as expensive as in other regions of Canada. For some, even cheap is more than they can afford. Living in an apartment can also be an issue, as you may be limited as to what sort of blinds you can install.

I have spent time in a tent in cold weather. one of the problems is moisture. if the tent is closed tightly,  to conserve heat it will become quite moist and the air stale. you will.  need to provide some ventilation.  if the air is moist it will seem colder more quickly. your bedding will get wet.

I've been practising 'living without gas' and experimenting with using my bed to finish off cooking things that take a while, like beans or rice.  
I bring it to a boil then wrap the whole pan in a large towel before popping it into my bed, cover it with my duvets etc to finish cooking. the secondary effect is that it warms the bed just before getting in!
Hope this is of use to someone
love and peace
Maj

A Friend of mine who lived in a small apartment kept the thermostat at 55 deg during the winter.  That was fine at night when he was bundled under blankets, but too cold for comfortable living during the day.  His solution was to build a small cardboard "fort", much like we all did when we were five.  Using scrap cardboard boxes and duct tape, he built a large box in his living room that enclosed his chair, a small table, a lamp, and his TV and computer.  Sort of a tiny room inside a bigger room.  When not out running errands or away at work, he spent most of his time cozy inside his fort sipping coffee and comfortably reading, watching TV, or working on his computer.  Body heat and the electronics kept the box warm, occasionally augmented by a small heating pad under his feet.

We have a bed tent that was used in a previous house for the winters. Just a couple of weeks ago put it up in our 'new' old rental which has more leaks than I can track down.

It's summer now, but the tent works to trap our window ac flow or box fan depending. Cooling a much smaller area same idea as heating a smaller area.  Efficient? No. But we can survive the hotter Midwest summer this way as well as the winter.

I wonder how to keep the water pipes from freezing and breaking through all this!

And it reminds me that one October a few years back we had a week long very cold snap… 8 F overnight in the metal sided shipping container I was using as a bedroom at the time…. why is another story


I had a 2 inch thick piece of memory foam as a mattress topper, I made a tent over the head of the bed by draping a blanket over the head board.  I like cold air for breathing but that was too much, and keeping my face under the covers was suffocating, and logistically complicated.  I put a down sleeping bag (I think that’s what I used) in between where my body lay and the cold metal wall.  What an experience of radiant unheating!  And I took a half gallon jar of very hot water with me to heat the bed.  For simply my body heat to warm that bed would have taken me hours.  Except for getting up in the night to pee, things were great.

Hearing all about these cold readiness plans makes me wonder about the heating in the new to me house I will be in next week.  I’ll have to at least have a contingency plan! Thanks for bringing this to my attention. The first year in a  new place is always a journey of discovery!

Bubble wrap on the inside of windows might be a good and quick way to reduce drafts and add a little more insulation. Put up in fall and take down in spring.

I am planning as a longer term project to modify my existing drapes to insulating curtains. Not sure if sewing in a layer of mylar sandwiched between the existing fabric and another fabric layer is the best approach versus quilt batting or a wool or flannel layer. Still trying to decide. I use them now to keep the heat inside on winter nights and outside on summer days but they could be made a lot more effective.

Wooden pelmets over windows can also cut down heat transfer and drafts. These were popular in the 1970s and I recall my parents house having them. One could rig up cardboard ones tacked or taped above the windows I imagine.

Dont forget about drafts around poorly fitting doors. Rolled up towel to block air flow under door. Or installation of insulating strips and thresholds from hardware store kits.

In a pinch we could use our winter sleeping bags - these are down mummy bags, each one is two bags that fit one inside the other and are seriously warm! I imagine army surplus stores might carry something similar.

I second the suggestion of hot water bottles and you can also use them as cold water bottles. In the heat dome last summer we chilled them in the freezer and pulled them out to sit with when the heat got unbearable. I filled them only half full of water to leave room for expansion. You can freeze water in used pop bottles (soda) and that also gives you a backup water supply. Again only fill the bottle partway for expansion. If you have glass or metal containers that are watertight they can also be used like a hot water bottle, wrapped in a towel. Either to sit with or to warm the bed when you first get in. By the time they are cool,  your body heat should keep you toasty.

If you have ceiling fans and the power is on, remember spinning in one direction draws warm air up to the ceiling and in the other direction pushes it down.

And about the fan blades: I had a neighbor come over last winter.  He puzzled over why I had the fans on going the direction I had them. He had heard that you were supposed to run them counter clockwise in the winter and clockwise in the summer- or the opposite, I don’t remember, but I was definitely not following the directions he knew and valued.

When I pointed out to him that it depended on the set of the fan blade he could not figure that out because I wasn’t following the directions. Definitely not a Permie!

If you look at the fan blade angle and look at what direction the fan is going to turn and then imagine the air getting pushed by the fan blade, it’s not hard to see what direction the fan is going to blow.

If you have the fan set to push the warm air up against the ceiling that same warmed air is going to flow down and heat your walls and make warm drafts.  Again depending on speed of the fan and dimensions of the room.

You may want to maintain the walls as cool as possible because they can absorb radiant heat or conversely they are radiating cool. As in all things Permaculture, look at all the elements and decide which way is best for your situation and objectives

Jay Angler wrote:Creighton Samuels wrote:

This is the same mattress pad heater that I've been using for 6 years

I use a mattress warmer but normally I turn it on for ~1 hour before bed and then turn it off as I get in (it conveniently has a built-in 1 hour timer!) However, it's a bit useless in a black-out which can easily happen in my area in any storm due to all the trees around us.

The mattress pad heater is low enough on demand that a deep cycle battery and a small inverter would be a workable solution; if only used as a pre-heat anyway, it'd work even better.

Luckily, we do have two wood burning stoves. They aren't anywhere near as efficient as an RMH, but if we're desperate, one is downstairs in a room that's easy to isolate, although fairly large. The one upstairs can't easily be isolated at all.  Our weather only occasionally gets ridiculously cold, so I'd be inclined to do the "hot rock" trick - heating them on top of the woodstove then tucking them into the bed for an hour.

Do you mean a "happy rock"?   Wherein you heat the rock up on the woodstove, shove your hand into a wool sock, grab the hot rock with the wool sock; pull in, twist once, push through so that you end up with two layers of wool around a hot rock, then place the "happy rock" under the comforter?  Yes, we do this too; with on the woodstove or on the gas stovetop, depending upon the details of the power outage.  I have 6 fist sized pieces of soapstone that live upon my woodstove for this exact purpose.

As in all things Permaculture, look at all the elements and decide which way is best for your situation and objectives

Situation and objectives are what this entire thread is about. We all have different situations. I'm not in the house I want to be in, if this was mine (god forbid, it's a POS, I have nightmares about having to buy it) I'd have very different solutions going on. So my factors are depending on my situation. Basically I think that having a back up plan in case you need it is VERY wise, and having it worked out well ahead of time is even better, gives you time to change things as you think about it.

I know a lot of people say "well I can't do this or that because it's a rental or I can't afford solar" etc.  And I agree, I'm one of them. So my weird solutions are designed to do what I can. I have this place about as insulated as it can be short of tearing out the walls and doing it right, and all the drafts I can access are  dealt with. I made shutters for the worst windows that hook with spring rods, magnets, and other non-damaging items, and all of the windows have some creative drapery going on for winter and summer.  But the place is electric dependent. And we lose power in ice storms. And I don't like what's going on with the grid. So I need ways to be ready if I have to do something else.

In the end, I hope people think about their own situation, in a worst case thing, what would YOU do? And I suggest, if possible, you get it ready to go now, so when you need it, it's already done.

My tent pole elastic came in the mail today, glad I ordered it now, I'd have been sad if I had tried to put up that tent in the house or any other time and found out it had bad elastic, and that I can't get any in town, had to buy online. You CAN use string, and I have, but elastic is MUCH easier.  Was worth putting up those tents to test them! And one eliminated itself as a possible for in the house, hexagon base, the space I can clear is rectangular. One probably eliminated itself as it's a pop up and the joints break, not flex. That leaves contestant #3 as the one I'm keeping accessible for emergency use this winter, it flexes, can be shortened by dinking with the poles, and has the right size and shape base.

Thekla McDaniels wrote:
If you have the fan set to push the warm air up against the ceiling that same warmed air is going to flow down and heat your walls and make warm drafts.  Again depending on speed of the fan and dimensions of the room.

You may want to maintain the walls as cool as possible because they can absorb radiant heat or conversely they are radiating cool. As in all things Permaculture, look at all the elements and decide which way is best for your situation and objectives.

I look at my objectives, and it leads to some odd things with fans. We have one ceiling fan here that I keep running 24/7/365  blowing toward the ceiling, on the lowest I can get it (wish I could get it's lower without rewiring it.) It is in the place in the house where the ductwork from the heat pump works against itself, and makes the house into two halves that the air doesn't flow correctly between them. The fan keeps them moving. When I started it, we checked the power bill, then turned it on the way I thought, and winter or summer, the bill is about 10.00 lower every month if that fan is on like that, and the house is more comfortable. It makes the heat pump work more effectively, by keeping it from fighting with itself.

Weird, but effective use of existing systems.
That's the kind of solution I like! All I had to do was figure it out, then remove the cord to the fan so it didn't accidentally get turned off.
:D

Worth repeating:

Effective use of existing systems… that’s what it’s all about!

Andrea, if you sandwich mylar between curtain layers, don't sew it as that will create holes where cold can infiltrate.  Instead maybe try spray adhesive, or figure out a way to seal the holes if you do sew it, or use some method that does not breach the layers.  I'm working on a design myself and learned that this can be a concern.  Good luck with yours!

Edit: This is why I should read all the replies... Sorry for the duplicate answer.

I didn't read all replies, but adding to the possible heat sources for inside a tent or small space: Hot water bottles.

In Japan they were a popular method of night-time heating about a generation ago. There are lots of ceramic ones that slowly radiate their heat for some hours into the night.

I've never used one because it never gets hot enough here that I feel like I can't stay warm by wearing another layer of clothes.

Donna Lynn wrote:Andrea, if you sandwich mylar between curtain layers, don't sew it as that will create holes where cold can infiltrate.  Instead maybe try spray adhesive, or figure out a way to seal the holes if you do sew it, or use some method that does not breach the layers.  I'm working on a design myself and learned that this can be a concern.  Good luck with yours!

Thanks Donna, I read a suggestion online somewhere that the best way to construct insulating curtains is to attach all the layers together along the top edge but only the outermost layers should be sewn together along the other three edges. Apparently this improves the hang of the curtains and minimizes unequal shrinkage if the curtains need washing. It would minimize making holes through mylar too.  Maybe it is possible to cover the top seam with tape or something. Or maybe just make a seam with a wide hem that could be folded over to cover the line of needle holes. That sounds easier. In any case it sounds like minimizing lines of sewing through the mylar would be smart. No quilting.

It seems there are heavier weights of mylar that come in rolls and are less flimsy than what I usually see in cheap emergency blankets. This sturdier and larger rolls might be good for wrapping Pearl’s tent to improve its heat retention!

I also read in someone’s blog that they had found some kind of fabric that already had insulating material layered into it. Not sure now if that was mylar or something else.

Gaps around the edge of the curtains might have a bigger effect than holes made during sewing. Recommended to devise ways to attach them to the window frame with velcro, magnetic strips, etc.

I'd go for extra layers of clothes. They go with you around the house. More efficient than a tent - smaller surface area.
We can also cut some losses - hot water down drains for instance. If you've just boiled a pan for veg, put the lid on the hot water until it's cooled down.

My thought on mylar and it may be wrong)  is that it's main usefulness is a reflector, it's not insulative. So covering it would be counterproductive. If I use it as part of a tent, I'd put it on the inside.

If I am correct about that (and I am not 100% sure I am) all mylar would do in a curtain sandwich is act as an air barrier, and there are cheaper things to do that with. But if I was going to sandwich it, I'd do the attach it only at the edges bit.

I am considering getting a roll of it for heat control in both summer and winter, reducing heat gain when we don't want it in summer. But if I use it in a tent, it'll be on the inside, uncovered.  

Although I live in NZ, without snow, my space has no insulation, double glazing or any heating whatsoever throughout winter.

CURTAINS
I have a special set of winter curtains made from wool. I take down the summer ones, and hang the winter woolens when the season changes.
They really make a difference.
You could cheaply source old blankets for curtaining at thrift stores in summer and make a set, and possibly use the woolen parts as a liner, with more attractive fabric for the side you are looking at.....
Old quilts would also work (cut to size), as long as you have laundered everything.
Forget mylar. Sheep wear all that wool for  a reason.
When did you last see a mylar sheep?

ER WHAT DO YOU CALL THIS? Indoor shutters?
I also have a large polystyrene block cut to the same size as the window near my sleeping space. It is covered in fabric, and I simply place it over the window at nightfall, to completely insulate the window. The fabric covering helps eliminate any drafts trying to creep in through the edges.
It s light and no trouble to lift into place and take down again.

CLOTHING..... THINK LIKE A SHEEP
I have special clothing, and sew special outfits constructed like quilts with old woolen blankets for the inner layer, and they are super toasty warm. I also have special sets to change into at nightfall that are even more snuggley so that as the temperature changes, so do I.
Making these clothes myself, I can craft them to be as warm and as cute as I want them to be. There are really no rules or limits. I source most materials second hand and my favourites are overalls make with vintage kimono wool, and a hooded parka make with a blanket baffle, lawn liner, and vintage kimono wools and cottons on the top layer.
I adore my clothes and making them. They make me feel more me than any bought item ever does.

DOWN SLEEPING BAG AND HWB
Also when I hang out, sitting and reading or sewing, I am always tucked up in a down sleeping blanket to conserve heat.
As a last ditch resort, I will fill a hot water bottle and snuggle it inside the down bag. Instant hypercomfort.

BED CAVE
I also have my bed set up in a Japanese mosquito net tent which warms the space when I am present in it.
I can stand up inside it (it is a little bigger than my bed), so it is both roomy and warming.  I even have a reading table inside, a lamp my favourite books and a floor cushion if I feel like a late night study session. (For which I first climb into my sleeping bag).

BED SET UP
I also have a special set up for the bed in winter. I would never sleep on the floor, if I could help it, as the bedding gets damp and the floor is cold and dust prone.
Bed is definitely the way to go, with it's own curtaining or tent.

I sleep on top of a double layer of down quilt in it's own duvet cover.
Then comes a vast linen duvet cover that I sleep Inside of , this is why it needs to be vast, so it also drapes down to the floor, and can be tucked in if I want. This performs better than sheeting to eliminate all possible drafts. Really, it does, believe me. It is easily removed for laundering, and keeps me toasty warm all winter......
Then INSIDE of the duvet cover I have an alpaca mohair single blanket that I snuggle under (against my skin). This traps an amazing amount of warm air, and can be pushed aside when I warm up, or replaced if my temperature drops, without my ever having to wrestle with covers on the outside and top of the bed.
Then the woolen duvet.... light and very warm.
Really, those sheep know a thing or two. Did I mention that before?
We in NZ have a lot of sheep. The place is known for it. You practically have to speak sheep to be able to come here.

HEADSES AND EARSES
Lastly, keep your head AND ears warm at night. Most body hear is lost through the head, so that is an important piece. I wear a super lightweight cashmere scarf which I can pull up around my head or a cashmere headband for over my ears. They are made from lightweight cashmere from an old sweater I found in the thrift store. Score!

SLEEPING BAG STRIKES AGAIN
You can even sleep Inside a down sleeping bag inside your bed if things get really cold. It is a little less comfortable but could be a deal breaker in the coldest conditions. And you get to stay IN your bed, up off the old and damp floor.

IN CONCLUSION
My bed is my tent.
You do not need to be cramped to stay warm in winter. You do need good air and clothing and bedding and drapes or bed insulation.
And all of these come before a tent because they are more comfortable, and better ventilated.....
Then, if that is not enough, crack out the tent, adopt a bunch of kittens and have a handy torch, a slew of batteries and some good reading.

Stay warm my friends, from New Zealand where is is coolish midwinter, and I swam in the icey cold Pacific for all of three seconds this morning to celebrate being darned stubborn.
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Pearl Sutton wrote:My thought on mylar and it may be wrong)  is that it's main usefulness is a reflector, it's not insulative. So covering it would be counterproductive. If I use it as part of a tent, I'd put it on the inside.

If I am correct about that (and I am not 100% sure I am) all mylar would do in a curtain sandwich is act as an air barrier, and there are cheaper things to do that with. But if I was going to sandwich it, I'd do the attach it only at the edges bit.

I am considering getting a roll of it for heat control in both summer and winter, reducing heat gain when we don't want it in summer. But if I use it in a tent, it'll be on the inside, uncovered.  

This makes sense, to me, in my own experience. Going through my divorce, a situation instigated by my ex left my 9yr old daughter and me in a very old (1,800s) house, in Kentucky with the only heat sources being 3 old blocked-off fireplaces which actually hadn't been blocked off very well, and sucked heat out. I stopped watching the temps in the house when it dropped down to 32°F (with ice on all the windows) in my bedroom - the warmest room in the house, with the outside temps continuing to drop. I layered mylar emergency blankets under the fitted sheet and over the flat sheet with comforters over that. We both crawled in, snuggled up, and slept very comfortably. The mylar held in our body heat, but needed the comforters on top to insulate us from the external cold. The mylar under the fitted sheet did the same, keeping our body heat from being absorbed into the mattress, and stolen from us.

I think mylar only works to reflect radiant heat loss.  And being a moisture barrier, protects against heat loss through evaporation from the skin, and blocks drafts.  

It probably does all that in an application like layering it into sandwich curtains… but it doesn’t stop the conductive heat loss… which we certainly feel.  So to get the most out of mylar, it’s most effective when not in contact with a cold surface or mass…. or a warm one

Andrea, Amazon has rolls of various different kinds of insulating materials available.  Reflectix is one kind I am considering.

Windowquilt.com has a pretty good design for a roll-down insulated curtain that velcros to the sides and bottom of the window frame.  It is called their economy model I believe.  I'll probably do something along that line for mine.

Someone asked me to elaborate on metallized mylar aka space blankets. Not sure why except maybe I'm the only one here who spent 3 winters in an onion. Comfortably.

They don't provide any significant insulation. They work by reflecting heat. Put the shiny side towards the body to stay warm. They might reflect sunlight to help keep someone cool in summer but I've never tried that. Many of them are semi-transparent so they might make reasonable summer window screens. Someone mentioned sewing them into winter curtains & was wondering how the holes would affect the function. Those would be such small holes I don't think that would be much of a factor. I think it would work quite well sewn into the interior. Not quite as good as on the outside but it would look better & more normal. If normal is a thing for you:) Mylar doesn't breathe so consider that if you're covering a tent or using a mylar emergency sleeping bag. I kept some air vents open in the onion even though that gave up some of the retained heat. During the day I kept the main door open so any accumulated moisture could dry out. Moisture will make you colder. I used the mylar on the outside of the tent even though it would have been slightly more effective inside. Outside was just easier to install & stayed in place all winter.

I keep a space blanket in several backpacks. One I take into the woods with me every day & one stays in my car. Just in case. They make good impromptu rain gear. They can be used for several other situations too. Slings, chest seals, hypothermia, possibly shock, waterproofing a bandage, carrying or capturing water, signaling, etc. It's lightweight, versatile, & relatively inexpensive compared to some other options. In an outdoor situation they make good backdrop for a lean to built near a campfire. The heat it reflects from the fire can make all the difference in comfort.

My response isn't tents, but related in trying to keep warm on cold nights without a heat source beyond your body and insulation.

Even here in Southern California, Riverside and San Bernardino counties can see some pretty cold winter nights. When I was single, I had 2 body pillows plus several regular pillows. I also had a couple of the heavy blankets with images like wildlife or floral print, often found (here at least) at flea markets or swap meets. I arranged my body pillows on either side of where I slept and one near my feet. Then I covered them with one heavy blanket creating a nest, and a second heavy blanket to go over me.
Going to bed a bit early so my body would heat my nest, and when I went to sleep I'd cover my head and allow my breath to assist in further warming the space, leaving a strategically placed small opening for fresh air. Once my feet were warmed I could sleep.

I like the idea of an indoor tent for the bed. I will consider trying it for my West Virginia winters.

A memory bubbled up today while thinking about this thread...

I college I knew  a guy who lived in an unheated house. He did something he called "sleeping with the laundry" He had four big sheets, safety pinned together two and two, into giant pillowcases, and his clean laundry was in one (the top one) and his dirty clothes were put in the bottom one. He slept between them. When he started getting cold at night because there wasn't much in the clean bag above him, it was time to do his wash.

Definitely using what was at hand, and the things at hand did not include a closet or dresser. So he killed a lot of birds with one rock here, kept his room neater as all his clothes were in one bag or the other, warmed up at night, plus had storage space for his clothes. In summer he slept on top of both bags.

Pearl Sutton wrote:When he started getting cold at night because there wasn't much in the clean bag above him, it was time to do his wash.  

Haha, awesome! Reminds me of my student bachelor days. It might be a harder sell now.