Awhile back, I posted about a motor home I was hoping to purchase. I found the perfect unit, price and everything else. However, after looking at my finances and considering licensing, insurance, storage, gas costs, etc. I decided I couldn't afford it at this time. And so, I bought this tent http://shopping.yahoo.com/852644860-camping-high-sierra-appalachian-family-cabin-tent/ It's very roomy an comfortable. My goal now is to make it as comfortable as the RV would have been. So, I bought some camp beds for comfortable sleeping, tent lights, etc. Now, I want to add air conditioning. I've read a few blogs about this subject and decided what I needed was a liner to provide insulation. Mind you, the A/C would rarely be used, but I am planning some summer trips to Florida, and anyone who's been there in the summer knows A/C is an absolute requirement. So, after looking for something ready-made, and not finding it, I decided I need to make my own. At first I was looking at polyester fiber filled fabric, but it was way too expensive for the size I needd ( approximately 350 square feet ) Next I considered polyethelene foam aka "shipping foam fabric." I looked up the thermal conductivity and calculated the R-value to be just about 1 for a sheet 1/4" thick. That's not great, but I ran a quick calculation using a 5,000BTU unit to see what I can expect: ΔT=1/c*Q/A, or 1*5,000/350 = 14.3. So, in essence I can cool the interior by almost 15 degrees with a small 5KBTU unit. Now the best part, our S&R department throws away reams of this stuff that they receive as packing, so all the material is free. in the equation above; c=thermal conductivity = 1/R where R is the "R" rating. Q=Heat transfer 5KBTU A=area of liner = 350 sq feet - I'm only lining a portion of the tent as the front is a sort of screen room.