Thermal damping is the ratio of indoor swing to outdoor swing: \[ \Delta T_{\text{indoor}} = 38 - 34 = 4^\circ\text{C}, \] \[ \Delta T_{\text{outdoor}} = 42 - 30 = 12^\circ\text{C}. \] Damping factor: \[ D = \frac{\Delta T_{\text{indoor}}}{\Delta T_{\text{outdoor}}} = \frac{4}{12} = 0.3333. \] Thermal damping in percentage: \[ D_{\%} = (1 - D)\times 100 = (1 - 0.3333)\times 100 = 66.67\%. \] Final Answer: \[ 66.67% \]
Using the following values of thermal conductance, surface conductance, and thermal resistance, the U value across the given wall cross-section is \(\underline{\hspace{1cm}}\) W/m\(^2\)°C (round off to 2 decimal places). 
