In this paper, we focus on the steady-state heat transfer in an in situ constructed, insulated, reinforced concrete wall. The wall consists of two reinforced concrete slabs that sandwich an insulation layer. The two halves of the wall are joined by a series of steel wires to provide the needed structural integrity but unavoidably act as thermal shunts that increase the heat transfer rate. Nonetheless, the thermal performance of the wall surpasses that for an uninsulated wall because of the presence of the insulation. We compare the heat transfer rates predicted by a three-dimensional, numerical model with laboratory test data. The results from these data, and from numerous sensitivity studies performed with the model, show that the steady-state heat transfer in the wall may be approximated by the isothermal planes model. A more accurate estimate is obtained by a weighted average of the isothermal planes result and a simple parallel path model in which the isothermal-planes result is weighted by the factor 0.85. An appropriate value of the weighting factor, specific to a particular wall panel configuration, may be obtained using a correlation and graphical results that are presented in the paper. These quantitative results for the steady-state panel conductance are expected to be useful in exploring manufacturing strategies that would improve the thermal resistance of the panel, in designing energy-conserving buildings that employ such panels, and in establishing accurate energy standards and energy code compliance methods.