In the design of a cold-storage warehouse, the specifications call for a maximum heat transfer through the warehouse walls of 30,000 joules per hour per square meter of wall when there is a 30°C temperature difference between the inside surface and the outside surface of the insulation. The two insulation materials being considered are as follows: Conductivity Insulation Material Rock wool Foamed insulation Cost per Cubic Meter $12.50 14.00 (J-m/m²-°C-hr) 140 110 The basic equation for heat conduction through a wall is: K(AT) Q = L where Q=heat transfer, in J/hr/m² of wall K = conductivity in J-m/m²-°C-hr AT=difference in temperature between the two surfaces, in °C L= thickness of insulating material, in meters Which insulation material should be selected?