With the growing building energy consumption, people have to pay more and more attention to adopt new methods, new techniques to save energy. The hollow block ventilated wall is a new building envelope with the cold air in summer and hot air in winter flowing into the cavity, which can carry away the cooling and heat stored in walls. The cooling and heating loads of the building can be greatly reduced or even eliminated by removing the outdoor environmental effects on the building envelope, it has important significance for building energy efficiency. To obtain the thermal performance of the hollow block ventilated wall, a simplified dynamic thermal network model using RC-network method is established in this study, and the parameters are optimized using genetic algorithm. (C) 2015 The Authors. Published by Elsevier Ltd.