Shaping the Energy Efficiency in New Buildings - Building Energy ...

thermal requirements for roofs, floors and windows because it has particularly stringentrequirements for electrically heated buildings. Canadian U-factors for buildings withnatural gas heating are much lower. The United States has the most stringentrequirements for walls. Excluding Canada’s electrically heated buildings, India has themost stringent wall requirements and China has the most stringent window U-values.China’s thermal requirements for opaque building envelope components for commercialbuildings are average for this climate zone. Figure 4 highlights the window U-factors,while Table 13 provides details on the range of requirements in the very cold climatezone.Figure 4 Comparison of Wall U-factor Requirements in the Very Cold Zone0.60.50.4U-factor0.3Low maximumHigh maximumMidpoint0.20.10Harbin, CHN(Residential)Calgary, CANHarbin, CHN(Commercial)Duluth, USALeh, INDTable 14 Thermal Characteristics of Roofs, Walls, Floors and Windows in the Very Cold ZoneCitiesCalgaryCANHarbinCHNMaximum U-factors W/(m²·K)Window IndicatorsRoof Wall Floor Window0.22 (Type I),Maximum U-factor:0.29 (Type II0.33 (Non natural2.80 to 1.40 (Non naturalby electricitygas), 0.55gas) and 3.40 to 1.90and other), and(Natural gas)(Natural gas) by WWR.0.47 (Type IIOthers)0.23 (Type II),0.29 (Type IIInon naturalgas), and 0.47(Type IIInatural gas)0.30-0.35 0.40-0.45 0.40-0.45Maximum U-factor: 3.0 to1.7 by WWR0.30-0.50 0.40-0.52 0.30 to 0.52 Maximum U-factor: 2.544