Comparative Study Of Sino And American Building Energy Efficiency Codes And Standards

Design Codes or Standards for building energy efficiency are the starting point of building operating energy consumption control. The first design and evaluation criteria for energy conservation in new buildings in the world was issued in America in1975, and after40years development, the standard system of building energy efficiency design has been developed maturely and steadily. In1986, the first building energy efficiency design standard of China was issued, and related standards and codes have covered almost all building types and climate zones, in the order of north to south, the residential buildings to the public buildings during the30years’development, and made great achievements.Since the two nations both have vast territory and various climate types, furthermore, China’s design standards for building energy efficiency have strong original relationships with those of America historically. In the background that energy conservation has become China’s basic state policy, the main purpose of this doctoral dissertation is to explore the similarities and differences between the two nations’ building energy codes or standards and the causes of similarities and differences, as well as the impact of these similarities and differences in code development, implementation and enforcement of the standards produced, in order to provide new perspectives and viewpoints for the China’s building energy standards for future development and updates.The research mainly used comparative analysis method and combination of logical deduction and simulation analysis method from various aspects, and drew the following conclusions:1. Comparisons of both nations’building energy codes or standards from the perceptive of historic development, is to investigate and compare the economic, social and technical backgrounds, and development history when the codes or standards were developed and updated, as well as the effects by the standards. The study found that there were huge differences between the two nations in the initial conditions and original intentions. The different levels of economic development and social and political systems, the differences of basic research inputs in the field of building energy efficiency, and the role of government were all reflected in the development history of building energy codes or standards.2Comparisons of the mechanisms for the development process, adoption, implementation and enforcement of the two systems. Studies showed that China adopts single standard system run only by government, which lacks dedicated institutions and full-time staffs, and the mechanisms for the development process, as well as openness and transparency during the process. The United States uses diverse standards system, non-government codes or standards has priorities, in which the government only plays the role of assistance. Openness, transparency, balance and competition are important differences compared to china in the code development and process. In the perspective of implementation and enforcement, building energy codes or standards have legal forces once they are issued in China, implementation and enforcement will be supervised in the stage of design and construction individually. In contrast, building energy codes can be adopted in practice only through legislative action or by regulatory action in most states or local level while codes are published or updated in the United States. The code officials will be in charge of the whole enforcement process in their system.3. Comparisons of ideas for building energy codes or standards development. The research revealed that China adopts an overall strategy to develop building energy standards according to building types and climate zones step by step, and proposed buildings need compliance with the given energy consumption level regardless of building size and height in most building energy standards. In contrast, one standard was initially required to cover all building types and whole territory in the United States. The building energy codes do not set clear energy efficiency goals, but focus more on economic and technical feasibility and cost-effectiveness that can be widely accepted.4. Building shape coefficient, which is one of the most important difference between the two systems. This concept becomes more and more important in most china’s energy codes, however it is never adopted in the America’s, and this difference results in a series of other differences between the two systems.This section critically studied the problem of that the building shape coefficient applied into China’s building energy codes, revealing that there is a logical flaw for the concept to be used in building energy codes or standards, and there is a need for additional preconditions. In the non-heating areas, there are no relationships between shape coefficient and energy assessment indicators in the non-ideal operating conditions. The study also pointed out that in the heating zone, from the perspective of building energy conservation assessment indicators, the dimensionless parameter, the ratio of the surface area to the building area is more accurate than the building shape coefficient, and will not bring fundamental changes to the existing standards update.5. Comparisons of compliance paths. The research revealed that the similarities and differences of compliance path for prescriptive buildings envelope option and performance-oriented buildings envelope option of both country’s building energy codes or standards. The research indicated that in China’s standards, some similar concepts have different connotations, and different terms have the same definition.The study also pointed out that combination of prescriptive design requirements and performance-oriented option is the general trend of the development of standards or codes in the world, however provincial standard of Wuhan cities circle adopted prescriptive buildings envelope option as only an compliance approach, which will limit the architectural creation, meanwhile will lead to a certain level of homogenization of new buildings. Obviously it lacks convictive evidences.