You are given a passage. You need to construct a question about the information present in the passage. Construct a question in such a way that (i) it is unambiguous, (ii) its answer is the whole paragraph. Avoid creating questions that can be answered correctly without actually understanding the paragraph.

There are such values, called R-values.  They define the resistance to heat loss per unit time, temperature difference and area (i.e., higher is better).  These are English units, hour-degreeF-ft^2/BTU.  An R-value of 20 means that 100 sq. ft. of wall separating a 20 deg F temperature difference for 8 hours passes 800 BTU of heat.  Typical recommended R-values (ref. 1) for use in residences are 4 to 60, depending on climate and location in the house.  For walls the range is 11 to 28.  In the ref. 2 web site you can find R ratings for various insulation materials, in R-value per inch of insulation thickness, and thicknesses required for various recommended R-values.
What's the rate of heat loss through a domestic well-insulated wall per sqm when the heat differential is 15C?