The structural response of Insulating Glass Units (IGUs), formed of glass plates sealed by perimeter metal spacers entrapping a gas, is strongly influenced by the complex interaction between the glass plates and the gas, as well as by the structural coupling of the plates through the spacers. The former effect, called “load sharing”, depends on the flexural stiffness of the plates and the pressure variation of the compressible gas due to applied actions. The more accurate and direct model to evaluate the load sharing is the recently proposed Betti’s Analytical Method (BAM) (soon included in the new Eurocode on structural glass), which allows to evaluate the IGUs response under the most various support conditions and external loads. In this paper, the BAM model is revisited, and the result obtained by means of conjugate BAM-numerical analyses are carefully validated by means of comparison with the results of experimental tests. In particular, the results of an extensive experimental campaign, performed on Double GUs (DGUs) subjected to line-distributed and concentrated loads, both at the environmental and at high temperature, are presented. To properly account for the influence of geometric parameters on the DGU response, elements with various aspect ratio, glass thickness and cavity thickness have been considered. •The validation of BAM model for DGUs was made.•Complete analytical/numerical/experimental analyses for DGUs were carried out.•Structural effects of variations of gas temperature were considered.•“Load sharing” mechanism under linear/concentrated loads was studied.•Results were presented in terms of temperature/load–deflection responses.