Summer thermal comfort is often a problem encountered in internal insulation buildings with low inertia. To lessen these problems, Phase Change Materials (PCM) can be used and introduced in walls. Some studies have already been carried out on this subject introducing PCM in concrete wall, in plaster board, in light internal components… conclusive that it is a great solution to improve building inertia. In this paper, experiments on a glass block wall containing PCM are carried out. The experimental setup is described and results are discussed for three MCP. These experimental results are used to assess a one-dimensional model developed in TRNSYS, which is used to study how phase change materials affect model houses thermal performances. Some differences are observed between experimental and numerical results and are explained by several reasons.