Double layers SSPCM wall could improve indoor thermal performance and reduce building energy consumption for a whole year. SSPCM layer with higher melting temperature was active in hot seasons and that with lower melting temperature was active in cold seasons. One SSPCM layer on external and the other one on internal wall surface was named "SSPCM wall I". Two SSPCM layers on internal surface was named "SSPCM wall II". Location of SSPCM layer affected heat transfer process of building envelope. In order to improve performance of double layers SSPCM wall by optimal location, two dynamic heat transfer models of double layers SSPCM walls in Wuhan city were developed by TRNSYS. The results showed that room with SSPCM wall I could reduce energy consumption 20.51% in winter and 0.65% in summer compared with room with reference wall I. And room with SSPCM wall II could reduce energy consumption 18.75% in winter and 13.46% in summer compared with room with reference wall II. The indoor air temperatures of rooms with SSPCM wall I and II were all in comfortable range for a random selected day both in winter and summer. The optimum melting temperature of SSPCM layer was close to set point of indoor air temperature. It was 0-1 degrees C higher than set point of indoor air temperature in winter and 0-2 degrees C lower than set point of indoor air temperature in summer. (C) 2017 Elsevier B.V. All rights reserved.