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According to the U.S. Department of Energy, about 40% of total energy is consumed on buildings in industrialized countries, among which 68% is electricity. Recently research shows that 20%∼30% of building energy consumption can be saved with optimized operation and management without changing building structure and hardware configuration of energy supply system significantly. Therefore, there is a huge potential for building energy savings through efficient operation.

Abstract Air source heat pumps (ASHPs) are widely used in various types of buildings in different regions of China. Considering the significant differences in the characteristics in heat source side and user side, providing different products for different zones is an effective strategy to promote the systematic development of the ASHP technology. To realize the goal of energy conservation, standard rating conditions are extremely important. The principles for determining the standard rating conditions based on a two-side (heat source/user side) multi-grade (different conditions) method were proposed along with the development of related standards. Therefore, the establishment of standard rating condition is introduced and summarized systematically. For heat source side, the standard rating conditions for heating were classified into four types according to the lowest ambient temperature (−25, −12, −2, 7 °C), while for cooling they were constant (35 °C). For user side, the conditions for supply air (20/27 °C for heating/ cooling), floor heating (35 °C), radiator (50 °C), fan coil unit (41/7 °C for heating/cooling), domestic hot water (55 °C), and industrial use were also determined. This study introduced the implications on ASHP by different standard rating conditions, especially the technical requirements, which indicated the necessity of providing different system cycles and compressors. The energy savings and economic benefits were also evaluated. The primary energy saving rate reached 15.3% and 41.6% compared with coal heating and conventional ASHP respectively by using low ambient temperature ASHP. The results showed that these standards have been satisfactorily developed.

The DC distribution system is an important development direction of the distribution system, which can improve the reliability and the quality of the power supply, and support the new energy, the energy storage, the electric vehicles, and the flexible access of AC and DC loads to grid. To realize the demonstration application of the DC distribution technology, China’s first demonstration project of the medium voltage DC distribution network will be built in Zhuhai, Guangdong Province to support the construction of the city energy internet. First, this paper analyzes the demand of the DC distribution network project, and puts forward the construction content and construction target. Then, it designs and analyzes the electrical connection mode, system operation mode, and startup and shutdown mode of the DC distribution network, and proposes the overall project construction plan. Finally, it conducts the specific project design and analysis, which mainly include the selection of equipment such as inverters, DC transformers and DC circuit breakers, the design and analysis of the DC control and protection system, the design and analysis of the over-voltage protection and the configuration scheme of the lightning arrester, and analysis of the system transient characteristics. The design and analysis of the engineering program is a combination of China’s distribution network engineering practice and technical characteristics, which lays a solid foundation for the advancement of the DC power distribution technology in China, and has reference value and demonstration effect for the design and construction of other projects.

Abstract The automotive operating protocols is a comprehensive expression of a country or a region’s road, climatic environment and driving habits. It is the foundation of energy consumption, test method and limit method for automobile products. It has direct impact on R & D, production and government access management of enterprises. For fuel cells vehicles, the lifetime is one of the main factors restricting their commercialization. Furthermore, the lifetime evaluation methods and its standard specifications of vehicular proton exchange membrane fuel cell are the critical factors to its technological development, but there is no authoritative recognized life evaluation method and test protocols so far. A logical fuel cell durability test protocol is the fundamental for developing the fuel cell life evaluation methods. A review on the state-of-art in the world for fuel cell accelerated test protocols was given, the research circumstances of different universities and research institutions in China, America, the European Union, Japan and so on are analyzed and summarized in detail. Then the essential characteristics and applicable environments of a comprehensive and effective durability test protocol are summarized based on the analysis and demonstration of the existing durability test protocols in literature. The work in this paper focuses on the research of durability test protocols of the fuel cell stack for the first time. The final conclusion will provide theoretical basis for establishing fuel cell durability test specifications and proposing life evaluation methods, and make a contribution to the long life research of vehicular fuel cells.

Abstract Air change rate is a very important parameter for indoor air quality estimation as it influences the exchange of air pollutants between indoor and outdoor environments. Consequently, determining air change rate distribution is indispensable for assessment of a population's exposure to air pollutants. In this study, the annual and seasonal average infiltration rates (air change rate for window close conditions) of 180 representative residences were simulated using the multi-zone network airflow model (CONTAM) to understand the residential infiltration rate distributions in Beijing. The representative residences were selected by probability sampling based on building characteristics, including building type, floor area, number of rooms, construction year, number of floors, and building orientation. The results show that the annual average infiltration rates in Beijing range from 0.02 to 0.82 h−1 with a median value of 0.16 h−1. The empirical distributions of the annual and seasonal average residential infiltration rates in Beijing were provided. The annual average infiltration rates were also found to well fit a two-parameter lognormal distribution, the median and standard deviation of which is −1.79 and 0.62. Infiltration rates of 34 residences in Beijing were measured via the CO2 decay method, and the measured infiltration rates of residences matched the simulated distribution well. The differences between the simulated and measured infiltration rates are discussed.

Abstract The civil nuclear energy deployment in China is important for future “Nuclear Renaissance” of China and worldwide. Compared to the other nations that developed their nuclear power energy system in last century, China can take advantage of the research and mistakes made by those states with regards to the back-end of the nuclear fuel cycle (NFC). The spent fuel accumulated by decades of operations of civil nuclear power is today a big burden for the nuclear industry. China must carefully plan the NFC for a sustainable development of the nuclear energy with special consideration to closing the fuel cycle. The present paper addresses the NFC option and implication of a LWR reactors scenario development and of a fast reactor park developed after 2035 and 2050, and covers the historical development of nuclear energy in China (i.e. from the first criticality of the first reactor) to the year 2100. The paper studies the partition and transmutation strategy with the use of accelerator driven system (ADS) to burn the MA to understand the ADS impact on the NFC and to estimate the number and the necessary deploying schedule of the ADS reactors to limit the minor actinides stock build up. The code INFCIS developed by the International Atomic Energy Agency (IAEA) is used in the present study.

Abstract Motor vehicle emissions contribute significantly to air pollution in Beijing. Therefore, a number of measures have been taken to control emissions from motor vehicles, including the elimination of high-polluting old vehicles and driving restrictions. We compared the pollution reduction effects and implementation costs of these two policies. The results showed that an average annual investment of about 1.7 billion RMB was invested in a policy of eliminating old vehicles in Beijing, resulting in annual emissions reductions of about 22,600 tons of CO, 1330.2 tons of NOx, 2197 tons of HC, 78.6 tons of PM2.5, and 81.3 tons of PM10. Meanwhile, a driving restrictions policy resulted in an annual loss by consumers of more than 17.84 billion RMB and annual emissions reductions of just 12,000 tons of CO, 845 tons of NOx, 1356 tons of hydrocarbons HC, 53 tons of PM2.5, and 57 tons of PM10. A policy of eliminating old cars is more cost-effective than a driving restrictions policy, policy formulation should take into account the cost-effectiveness of policies.

Abstract Traditional life cycle assessment (LCA) methods are used to conduct building environmental impact assessment (EIA) with little consideration of influential factors that vary in time and of variation in occupancy behaviors. Because the life cycle of a building is quite long, such details have significant influence on the accuracy of evaluation results. To fill in this gap and extend the LCA system, this paper developed a dynamic assessment framework based on LCA principles after reviewing the research progress of DLCA (dynamic LCA). The new framework identified four dynamic building properties (i.e., technological progress, variation in occupancy behavior, dynamic characteristic factors, and dynamic weighting factors) and considered them in corresponding assessment steps to realize real-time EIA. In addition, residential occupancy profiles were described at personal level, family level, and social level; and three potential quantification methods were introduced to explore the relationship between occupancy profiles and household energy consumption. The DLCA framework expands the connotation of the LCA system from a dynamic perspective, making it possible to present time-varying EIs of buildings over their long life cycle and guide occupancy behavior in time. This framework has the potential to be base for developing a useful tool for conducting forecast evaluation and promoting sustainability.

Abstract Effective low carbon transport policy-making needs to first understand what are the factors influencing residents’ modal choice and how it can be intervened. This study uses a discrete choice model to analyse the factors influencing residents’ mode choice in Beijing. A questionnaire survey was conducted in 2015, with sample data containing 865 respondents and 1704 trips collected. The results suggest that residents’ mode choice is closely related to their characteristics. Moreover, our study has linked residents’ mode choice with travel carbon emissions and estimated the emissions reduction potential of those policy measures aiming to improve public transport. For commuting and education trips, public transport improvements can reduce carbon emissions by 12.3~16.6% on average, but for other trip purposes, the reduction is only 2.9~6.8%. As commuting and education trips account for the largest proportion of urban residents’ daily travels, it suggests that policy should primarily focus on the improvement of public transport and its particular support for major commuting routes.