Retaining Heat During an Emergency

I've been wanting to be better prepared in keeping the house warm in case of an emergency.  Our main floor is pretty open with a lot of open doorways, so I've wanted to section off the family room with the fireplace and the kitchen.

I thought it might be smart to buy some foam board and cut it to fit in the doorways.  Shortly after purchasing the foam board, I went to a neighborhood class on emergency light and heat.  The instructors suggested taping those space blankets in your doorways. Duh!  That would have been a lot easier and cheaper than foam board!  Oh well, but I do think these will do a better job.

We had enough for solid pieces in some of the doorways.

But others I had to piece together.  It was easiest to cut with a utility knife like you're cutting sheetrock.

We're storing them in our garage suspended against the wall near the ceiling.