one of the "tricks" some manufactures use to build large R-factor numbers is to treat reflective values as if they are R-values .... example: an aluminum space blanket has higher reflective values but very little R-value .... the best way is to see if the line of camper being considered has been certified by an independent source (Dometic for one) which test campers and provides high and low temp ratings .... from Dometic getting such certification is free to manufactures .... if a company won't tell you the rating or won't submit their campers for testing, that says more than any claimed R-values .... in addition they play games with the ratings given .... example side wall values don't take windows into consideration .... with regular RV window glass having an R-value of 1 and Thermopane having an R-value of 2, campers with large windows can't possibly have high numbers for the entire surface of a side wall .... many have little or no insulation is slide floors and/or walls .... knowing the construction and having the unit tested to see how it performs is far more important than any single set of numbers
Jim
