What is the k-value or the R-value of ASTEC and how do these values compare with mass insulation?
The R-value is the measure of the resistance of a material to heat flow (or heat gain) by conduction only. The k-value is the measure of thermal conductivity; it measures the rate of heat transfer by conduction through a material from face to face. The R-value is always the reciprocal of the k-value. For instance, R = L/k and k = L/R where, R = thermal resistance, L = thickness, k = thermal conductivity; R-19 means 19 hr ft2 ˚F / Btu or 3.34 m2 ˚C/W. ASTEC’s thermal conductivity (k-value) is very low (0.00345 W/m K or 0.00199 Btu/h ft F). A very low k-value indicates a good conductive insulator. But the R-value depends on thickness and the thickness (L) of ASTEC is so small that the resistance (R-value) is not given serious consideration. What really counts in preventing heat transfer is solar reflectivity. R-value (resistance) is only valid when “managing” heat which has already transferred. To compare ASTEC’s thermal resistance (R-value) to the thermal resistance of polystyrene or of
