A method is described for measuring the radiative and gas conductance of vacuum glazing while at room or elevated temperatures. Such measurements are used to determine the residual gas pressure, permitting studies to be made of the accelerated degradation of vacuum glazing. The heat flows associated with this method have been analysed using a detailed finite element model and the technique has been calibrated against both high accuracy measurements on a guarded hot plate apparatus, and calculations of the thermal conductance due to radiative heat transfer. The technique is reasonably accurate-total uncertainties are less than about +/- 5% and measurements are reproducible to about +/-2%, for temperatures over the range 20-200 degrees C.