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

3.3 Building EnvelopeKey Findings All countries have requirements regarding the building envelope in their buildingenergy codes. These requirements cover thermal characteristics of buildingenvelope components such as roofs, walls and windows. Australia, China, India, Japan, South Korea and the United States address shadingin their building energy codes. Australia, China, India, Japan and South Koreaalso mention orientation in their building energy codes. In comparing U-factors for walls, roofs, floors and windows across four climatezones, no one country stands out as having consistently the most stringentrequirements. India tends to have relatively low U-factors (or high efficiencyrequirements), although at present, the prescriptive requirements are notmandatory. Japan has relatively stringent requirements regarding windows incommercial buildings. China tends to have lower requirements than the majorityof countries in many categories, but not by dramatic amounts. The United Statesin some categories has the most stringent requirements, and in others is the leaststringent, particularly in the warmest zone. For example, the United States overallhas the most stringent requirements for roof insulation in single-family homes.Canada has comparatively stringent envelope requirements for buildings heatedwith electricity, but generally less stringent requirements for other types ofbuildings.Building envelope refers to building components that separate indoor space from outdoorspace, exterior air or the ground. The main building envelope components include theroof, walls, floors, doors, windows and skylights. The thermal characteristics of thebuilding envelope are widely believed to be the most important topic in building energycodes from the perspective of impact on energy use. Building energy codes in all APPcountries cover building envelope requirements among one of the first issues addressed inthe text of the codes (Table 8).Table 9 Building Envelope in Building Energy Codes of APP CountriesSection Title (s)Main ContentBuildingEnvelopeAUSBCA 2007ExternalWindowBuilding SealingBuilding envelope must have insulation that complies withthe Australian-New Zealand standards (AS/NZS 4859) 29 .There are detailed provisions on how insulation is to beinstalled, and requirements on the degree of thermalresistance in roofs, walls, floors and skylights.Energy efficiency characteristics of windows.Building sealing for chimneys and flues, skylights, windowsand doors, exhaust fans, construction of roofs, walls andfloors, and evaporative coolers.29 AS/NZS 4859 provides general criteria, technical provisions and test procedures for building insulation.34