From thermodynamics, we know that the coefficient of performance of an ideal air conditioner \(\left(C O P_{\text {ideal }}\right)\) is given by

\[C O P_{\text {ideal }}=\frac{T_{L}}{T_{H}-T_{L}}\]

where \(T_{L}\) and \(T_{H}\) are the room and outside temperatures (absolute). If an \(\mathrm{AC}\) is to keep a room at \(20^{\circ} \mathrm{C}\) when it is \(40^{\circ} \mathrm{C}\) outside, find the \(C O P_{\text {ideal }}\). Convert to an \(E E R\) value, and compare this to a typical Energy Star-compliant \(E E R\) value.