If you can not afford to buy emergency heat sources, you need to know how to stay warm. You can make a shelter around your bed to trap body heat to stay warm.
Your shelter needs to be small so that your body heat will be enough to warm the space in it. If you have more than one person, you need to make it so that you share the space so that more body heat will be trapped in it to keep you warm.
You need at least 15 inches of insulating material around your body heat shelter. That can be whatever kinds of fiber you have in your home. I plan to use couch and chair cushions, blankets, and linens around mine. I can get 15 inches out of them. If you do not have 15 inches from these items, you can add any clothing you are not wearing and books and papers.
You will need to find a way to support these items around you when you place them around your shelter. Chairs and a table or curtain rods or closet poles are some of the ways you can hold up your body heat shelter.
You need to allow vapor from your breath to get out of your body heat shelter so that it will not get damp inside. This is especially true if you have used plastic as part of your shelter. Plastic traps the heat well, but does not breathe at all.
You will need to allow fresh air to come in as well. When you make your openings for vapor to escape your body heat shelter, remember that warm air rises and cold air drops. You can get fresh air from a low spot and let out the vapor-laden air at a high spot.
If you have pets, you will be much warmer with them inside your shelter too. If you can not manage to do this, you need to provide shelter for the pets and make sure their water does not freeze.
You also need to make sure your own water does not freeze or have a way to thaw it. Bringing water into your body heat shelter will melt ice eventually. It will make you a little colder in there, however.
Since I live in a cold place I have made my bed into a body heat shelter for all the time. I put a book case at both ends of my bed and put it all in a corner. I put boards across the two book cases for a top.
I bought a closet pole and made a curtain out of a heavy blanket and added more material to it so it is thick and insulates well. I hung the closet pole between the book cases on the edge of the boards. I used a piece of pvc tube before I got the closet pole. The pvc bends in the middle, so it does not work as well.
I used a large piece of cloth over the top of my bed before I got the boards to put up there. The cloth does not trap the heat as well as the boards, but it makes it quite a bit warmer anyway.
When you have an actual cold weather emergency in your home you will need to add inches of insulation around your bed to make it a good enough shelter. The top will be easy. The open side will be harder. I plan to add furniture to hold insulation up higher and hang some things from the top. Couch and chair cushions are a fast and easy way to get some thickness.
When you make a permanent cold weather shelter around your bed, you can lower your heat more at night and save on your heating bill. This is good for your pocket book and also for the earth.
If your bed is too warm in the summer, you can take the curtains off. The top of the bed is good for storage, especially unused bedding.
I put a small electric fan on the book case at the foot of my bed to cool it off when it gets too warm. You can adjust the temperature by opening the curtain, as well.
A clamp light attached to the book case at the head of the bed makes it nice for reading in bed. A battery operated touch light is another way you could do this.
My cats really approve of this bed shelter and usually sleep in there with me, even though I have a heated bed for them. I keep a container full of cat treats on the book shelf near my head. We are all ready to trap our body heat in an emergency.
I am adding a note because of a change in earthquake disaster preparedness. Having things directly over your bed is now considered bad for earthquakes. New studies show that you are more likely to get squashed flat by trying to hide under things. Please look at my more recent earthquake posts to learn more if you are in earthquake areas.