Consider a double-pane window. The glass surface may be treated with a low-emissivity coating to reduce its emissivity from \(\varepsilon=0.95\) to \(\varepsilon=0.05\). Determine the radiation heat flux between two glass sheets for case 1: \(\varepsilon_{1}=\varepsilon_{2}=0.95\), case \(2: \varepsilon_{1}=\varepsilon_{2}=0.05\), and case 3 : \(\varepsilon_{1}=0.05, \varepsilon_{2}=0.95\). The glass temperatures are \(T_{1}=20^{\circ} \mathrm{C}\) and \(T_{2}=-20^{\circ} \mathrm{C}\), respectively.