Experiment: Mylar insulation under-rug

[livewire516]

Admittedly, I just threw this together so I don't even have subjective results, and I don't plan to have a rigorous pre/post measurements.

I lived in a beautiful, old (read: poorly insulated) Queen Anne style house in West Philly. My desk is in the middle of the second floor bay window, meaning that the area of floor underneath is exposed to the outside. I've filmed the windows and bought insulating curtains, and threw down an area rug; however, even when wearing winter slippers, my feet get very cold pretty quickly.

I took an extra mylar space/emergency blanket from a first aid kit in my bathroom (Of course, I wouldn't recommend taking one out of a first aid kit in you car or camping bag). And taped it to the bottom of the area rug. It was just slightly larger the area rug itself so I folder over two edges.

It's my understanding that they largely work by reflecting radiant heat, so I'm unsure how much it will help my feet. Being directly in contact with the floor, I'm losing heat through conduction. However, it's my hope that it may form at least two modest air pockets between the floor and the mylar and the mylar and the area rug, as well as reflect any heat from my radiator-style heater when it's in use.

Please see the picture attached. I'd love any thoughts and suggestions and I plan to follow up to tell you (subjectively) if I think it worked. Any additional ideas for check, under rug insulation is appreciated!

[deborah]

You may want to put some of that plastic antislip stuff under the mat so it stays in place. Do you have a pelmet? Insulated curtains don't work particularly well if the air can easily come out at the top or bottom of the curtain.

[livewire516]

Both good points.
I would definitely agree that precautions should be made to prevent slipping because the mylar is pretty slick. It seemed unnecessary because it's a small rug, almost entirely covered  and held in place by the desk. Reading your post and now testing it, I'll probably use something to prevent slipping on at least the small part people may walk on.
I had to look up what a pelmet was but yes, I had planned to add valences above the top as well as flanking the sides of each curtain. Admittedly, I planned to do that more for light blocking purposes more than anything.

Subjectively, it seems as though by bare feet on the rug feel less cold that it would have on similarly cold days!

[GrowingTheGreen]

Radiant barriers really only work when there is an air gap.  What you're trying to prevent is conduction heat transfer.  Solid rubber mat will work well.  Try a yoga mat.

[livewire516]

Thanks Will, you've confirmed what I thought may be the case. 

I have rubber horse stall mats lying around; they're thick and larger than the area rug, but truthfully the area rug is already ugly and going to be taken out as soon as it's no longer cold.

I did some searching around and found a table of R-values of different floor materials, typical thickness, and R-value per inch thickness. Here's the link: http://www.houseneeds.com/learning-center/pex-tubing-radiant-floor-heating/flooring-r-value-different-materials

I also copied it into a spreadsheet so I could filter/sort, find it attached if you're interested.

It actually seems like the best option might be simply finding another carpet layer over/under this one!

[HipGnosis]

I was going to suggest cork, and I see it's pretty high on the R/inch.
You can buy big sheets of it from 1/8" to 1/2" thick. It's used for whole floor underlayment.
Or you can by cork flooring tiles or planks - also in different thicknesses.
Cork is both thermal and sound insulating.  It's also renewable.
I'd put cork over the whole bay.