The determination of the thermal resistance of a building envelope is fundamental for the evaluation of the thermal performance of buildings. This could help to evaluate and verify the energy efficiency performance of constructions before renovation, during construction, upon delivery and during use. Some methods exist in the scientific literature but they do not allow a systematic, accurate and rapid evaluation. This paper presents a numerical benchmark of identification methods used to estimate the thermal resistance of an opaque wall. The robustness of each identification technique is investigated in terms of bias and uncertainties. The proposed estimation approach is based on an active method, in which the structure is heated in order to create a temperature gradient across the wall, and on the analysis in dynamic regime of the thermal response of the wall. The investigated walls are internal wall insulation (IWI) and single-wall structures (SWS). The results of the numerical study show that RC model-based identification techniques are the most suitable to estimate the thermal resistance of IWI at a very low computational cost. Nevertheless, the modelling error being larger for the SWS than for the IWI, 1D transient heat equations should be preferred for the identification of SWS thermal resistance. The active thermal strategy allows a relevant estimation of the thermal resistance with an observation time of less than 24 h.