# Energy Saving Potential of PCMs in Buildings under Future Climate Conditions
## 6 Conclusions  
This study aimed to support the application of PCM technology in the building sector as passive alternative to save energy in the buildings and assess its influence on building energy performance under future climate conditions. However, use of numerical models is the fastest tool to assess applicability of specific technology or materials in the buildings, especially with regard to energy requirements under future climate conditions. As such, results presented in this study highlight the energy saving potential due to incorporation of various PCMs with different phase temperature in the building envelopes both for cooling and heating periods in humid and snowy regions in the hot continental and humid subtropical climates of East Asia (Seoul, Tokyo and Hong Kong). Utilizing PCMs-incorporated BioPCM, DuPonEnergainPCM, RubBITHERMPCM into the building envelope was shown to be a promising strategy to increase energy performance in buildings during both heating and cooling seasons in the humid regions (Seoul, Tokyo and Hong Kong) and snowy regions (Seoul and Tokyo) under future climate conditions. The highest energy savings achieved by using PCMs in those regions are: electricity savings of 4.48-8.21%, 3.81-9.69%, and 1.94-5.15%, and gas savings of 1.65-16.59%, 7.60-61.76%, and 62.07-93.33% in Seoul, Tokyo and Hong Kong, respectively. On the other hand, these materials (PCMs) can be used in both new buildings and existing buildings to improve their thermal performance and energy consumption reduction. PCM efficiency depends on the local climate zone, melting temperature, PCM location in the building envelope and thickness of the PCM layer. Especially, a PCM's optimum melting temperature for energy savings depends on the details of a particular climate zone, where PCM with a melting temperature outside the thermal comfort range does not provide energy reductions regardless of large future fluctuations in the temperature. The results also showed, the PCMs implemented in the building envelopes with melting point of 29 \({}^{\circ}\)C (BioPCM) and 25 \({}^{\circ}\)C (RubBITHERMPCM) have allowed achieving important reductions of electricity and gas consumption for cooling and heating periods under future climate conditions:  
For Seoul, electricity savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 8.21%, 8.18%, 7.81% and 6.91% respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 6.53%, 6.95%, 6.62% and 5.82% respectively. For Tokyo, electricity savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 9.69%, 8.78%, 7.94% and 6.60% respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 7.89%, 7.32%, 6.53% and 5.48% respectively. For Hong Kong, electricity savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 5.15%, 4.37%, 3.71% and 2.49%) respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 4.45%, 4.17%, 3.79% and 3.10%, respectively. For Seoul, gas savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 1.65%, 3.61%, 4.75% and 6.77% respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 3.25%, 5.51%, 7.36% and 9.72% respectively. For Tokyo, gas savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 7.60%, 22.94%, 30.13% and 38.43% respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 10.63%, 29.44%, 37.62% and 46.86% respectively. For Hong Kong, gas savings by BioPCM in present, 2020, 2050 and 2080 were shown to be 67.20%, 62.07%, 88.33% and 0.00% respectively and RubBITHERMPCM in present, 2020, 2050 and 2080 were shown to be 76.92%, 69.40%, 93.33% and 0.00%) respectively. Finally, Future climate change will not have much effect on the energy saving potential of a PCM with characteristics appropriate to the local climate and prevailing conditions. In future work, it would be interesting to answer the questions: What are the appropriate characteristics of the PCM within the local climate prevailing conditions?