The SI derived unit for heat density is:     joul per square meter (J/m²)

(CGS unit)   1 langley (Ly) = 1 (cal_th/cm²) = 41.84 kilojoule per square meter (kJ/m²

The SI derived unit for heat flux density is:     watt per square meter (W/m²)

The SI base unit for Thermal resistance is:   kelvin per watt (K/W)

The SI base unit for Thermal resistivity is:   kelvin meter per watt (K⋅m/W)