## 4 EnergyPlus Simulation Results
### Analysis of Energy Saving Rate in Different Climate Zones
Passive systems that are effective in New Delhi are high efficiency SHGC windows (double tinted low-e) and external blinds. Their energy saving rates were 16.0 and 26.0%, respectively. Among the active systems, the VAV system, the high efficiency centrifugal chiller, the combined VAV-ERV system, and the combined VAV-UFAD system are effective in New Delhi. These are air-conditioning and plant systems that can change hot and humid outdoor air to a comfortable indoor environment. The energy saving rates of these technologies, when compared with the base model in New Delhi, were 36.5, 41.4, 51.3, and 56.2%, respectively. The heating energy consumption was greater than the cooling energy consumption in Minneapolis, because of a high number of heating degree days (HDD). The primary energy consumption in the Minneapolis base model was 505.1 kWh/m\({}^{2}\), which was higher than that of Incheon. Passive systems that are effective in Minneapolis are the high-R insulation wall and the high efficiency U-value window (triple low-e), which significantly prevent heat loss. Their energy saving rates were 9.3 and 14.7%, respectively, when compared with the base case. The active systems that save more energy in Minneapolis than in Incheon are the high efficiency heating system, the combined VAV-economizer, the combined VAV-ERV system, and the active chilled beam with DOAS. The energy saving rates of these technologies, when compared with the base model in Minneapolis, were 36.9, 42.9, 45.4, and 55.7%, respectively. The effective technologies in Minneapolis are the control of the low outdoor temperature to create comfortable indoor environments, and technologies that utilize outdoor air or heat recovery. When the GSHP was applied in Minneapolis as a renewable energy system, the energy saving rate was 39.3%. Berlin has a higher HDD value and a lower CDD value than Incheon. Thus, its actual heating energy is higher than that of Incheon, whereas the cooling energy in Berlin is lower. The base model primary energy consumption in Berlin was 416.6 kWh/m\({}^{2}\), lower than that of Incheon. The technologies that are effective in Berlin are the high-R insulation wall and high efficiency U-value window (triple low-e), which are envelope systems that prevent most heat loss. Their energy saving rates were 7.9 and 12.6%, respectively. Among the active systems, the high efficiency heating system, the combined VAV-economizer, the combined VAV-ERV system, and the active chilled beam with DOAS showed higher energy saving rates in Berlin. The energy saving rates of these technologies for Berlin were 33.7, 40.5, 42.8, and 52.7%, respectively, when compared with the base case in Berlin. When the GSHP was applied in Berlin as a renewable energy system, the energy saving rate was 35.9%. The technologies that showed higher energy saving rates in Minneapolis showed similar trends to those in Berlin. Figure 11 compares the primary energy saving rates in four regions when using high-performance technologies. The energy saving rate of a technology differs according to the characteristics of the climate in which it is applied. The technologies that are more effective in hot regions are shading systems, such as the high-efficiency SHGC windows in Case 4 (16.0%), and the external Venetian blind in Case 5 (26.0%). In addition, air-conditioning and plant systems that can convert hot and humid outdoor temperatures to create comfortable indoor environments are the VAV system in Case 6 (36.5%), the combined VAV-rotary ERV in Case 8 (51.3%), the combined VAV-UFAD in Case 9 (56.2%), and the high-efficiency centrifugal chiller in Case 12 (41.4%). In cool and cold regions, envelope systems that prevent heat loss, such as the high-R insulation wall in Case 1 (12.2%), and the high-efficiency U-value window in Case 3 (14.7%), are effective.