| It is well accepted that energy saving is to be the way of changing the style of economic development and achieving sustainable development in different Countries. China which is a responsible big country commitments to achieve40%～45%energy reductions in unit GDP in2020, including the building energy efficiency as an important part of energy saving. According to the research reports of academician Jiang Yi and other scholars, China's construction operation consumption had dominated about25%of the total energy of national economy consumption in2001. With the development of economy, building energy consumption increases rapidly. According to data released by the authoritative department, the total area of large-scale public buildings is fewer than5%that of towns, but the total energy consumption accounted for more than20%of towns, and the national office buildings annual per capita power consumption is3072.5degrees in2007, about10to20times that of towns, we can see that building operation consumption waste is serious, and the efficiency of energy efficient use is very low. So researching on building, especially the effective use of public building energy consumption and operating energy problems, improving the energy efficiency of building, not only provide theoretical guidance of effectively reduce the energy consumption, but also play an important role of social benefits and economic benefits,which is of great significance to honor the solemn commitment of the country.The energy consumption of large and medium-sized construction especially public buildings is very high, and the phenomenon of energy wasting is very obvious, the potential of energy saving potential is huge. The main reason to create waste can be divided into two categories:the one is that the system design is not optimal, the equipment and the system efficiency is low. Such as "big horse draws small car" causes low efficiency of equipment operation; the other one is the Man-made waste, such as "ever-burning lamps" in the office and turn on air conditioning for a long time with no person in room. The waste generated about the former, there are a variety of theoretical results and the technical method to control and management the energy at present, but for the second phenomenon caused waste, there is not a better method to evaluate the situation of wasting, in order to take appropriate optimization strategy to solve this problem.In total energy consumption, the proportion of the air conditioning system is the largest. So the high and low efficiency of the air conditioning system is of great significance to building energy efficiency. The equipments which constitute air conditioning system has a clear energy efficiency indicator, but the indicator is usually detected in a particular condition (such as the power rating).In the actual using, operation condition often changes, the time to meet the rated operating conditions is very little, which is only about5%of the total working hours, the workload is only50-70%of full load in most of the time. The energy which the device consumed will certainly reduce in the low load. What is reasonable to reduce the amount of energy consumption? At present the common method of evaluation is to compare the average energy consumption or total energy consumption, it is clear that there is a large deviation in this evaluation. Regardless of any energy-using equipment, for specific building load, as long as the energy efficiency of the equipment or the system energy efficiency of the entire building is maintained at the optimal state, it can be said that the energy consumption is the lowest at this time, therefore we can take energy efficiency as a indicator evaluating the advantages and disadvantages of building energy consumption efficiency, which is more scientific. Energy efficiency can directly evaluate the efficiency of the equipment worked independently, but for the energy-using equipment which works in system mode, such as air-conditioning system, only by raising a single device energy efficiency evaluation to reduce system power consumption is not entirely feasible, the energy consumption status of running BAS(building automation system) building proved the limitations of this approach.Aiming at these questions, the article covers improving the energy efficiency in buildings, optimizing energy efficiency in buildings and launching the research, the main contents include the following factors:1. This article briefly analyzes the causes of high energy consumption, discusses the key issues that need to be addressed in reducing building energy consumption. Building palisade structure and building materials are one of the important reasons for the building energy consumption; The choices of equipment used in buildings are not reasonable, the "big horse draws small car" causes equipment efficiency declined and energy consumption increased; there exists serious waste in building; lack of theoretical support of building energy efficiency. Although it is impossible to change the load generated by building palisade structure, we can reduce human waste to improve the energy efficiency of building energy-using equipment and decrease energy consumption. At present, it is not very clear that the effect of research about building energy efficiency to reduce the system building energy consumption, So it is possible to effectively reduce energy consumption through solving the key basic theory of the building energy efficiency.2. This article analyzes the current situation of the building energy efficiency optimization and the existing problems. American Society of Heating, Refrigeration and Air Conditioning Engineers(ASHRAE) earliest adopted the energy efficiency to evaluate the work efficiency of the chiller, however, this method can not effectively evaluate the energy efficiency of the equipment throughout the work cycle, so ASHRAE and the relevant department in China have proposed an integrated part load coefficient of performance(IPIV), an integrated part of energy efficiency(IEER), seasonal energy efficiency(SEER), the design of energy efficiency(DEER) and other indicators, evaluating the overall operating efficiency of the chiller equipment from multiple perspective. In recent years, there began to have some reports which using the system energy efficiency to evaluate the system efficiency of the central air conditioning and implementing energy-saving control, but it is also limited to comparatively analyze the overall system efficiency in different states, not studying on the optimization theory that improve the system energy efficiency. Although the theoretical results of system energy efficiency are seldom, the projects focusing on the system energy saving have achieved splendidly results. Such as the BKS central refrigeration plant fuzzy control system developed by Huitong Huacheng, take a frozen station(chilled water pumps, chillers, cooling water pump) as a whole to implement fuzzy control, pursuing system rather than each of devices which is the most energy efficient, it can reach up to51%of the energy saving effect. Therefore, studying theoretically on the model of energy efficiency and optimization strategies to effectively reduce the energy consumption of energy-using equipment is of great significance.The energy consumption of building is to provide a comfortable working and living environment, even if the efficiency of the energy-using equipment is high, if the body does not take full advantage of the comfortable building environment, the energy consumption is invalid and meaningless. Therefore reducing the building energy consumption must establish the link between energy consumption and human use, study on the level of utilization of the human body for building energy consumption. This paper presents a model of the evaluation of the effectiveness of building energy consumption-energy using efficiency, Energy using efficiency provides an algorithm for the quantitative evaluation of the effectiveness of the energy consumption of building, Energy utilization efficiency model for the energy consumption facility of the building ends can provide energy efficiency optimization control strategy. The experiments show that the model of the energy use efficiency can quantify the degree of utilization of the human body for energy, screening the body's energy-using mode can find energy waste and optimal control the work state of the energy-using equipment, we can achieve the goals of reducing the building load and correspondingly increasing energy efficiency in buildings by reducing or completely cutting off the ineffective energy consumption output.3. Establish the system energy efficiency model of the buildings energy consuming equipment. Research the system energy efficiency optimization algorithm. Solve the uncertain target of energy efficiency optimization. Explicate the energy efficiency optimization goals and optimization strategy under different load. Energy using equipment is usually designed in accordance to meet the most unfavorable load conditions, but building load changes with time, weather and number of personnel. As the load changes, the efficiency of energy using equipment will change. Like submersible pumps and other independently working equipments, because of its inherent characteristics, it's unable to adjust its inherent energy efficiency, only by adjusting frequency, downtime and other measures to improve the characteristics of low load conditions, reducing the total working time to increase equipment energy system efficiency in a time period. For air conditioners and other system working equipments, optimization of energy efficiency of a single device does not mean the entire system energy efficiency optimization, and the pros and cons of building energy consumption is embodied through the entire system, rather than a single device. So under the conditions of maintaining energy using equipment to stabilize working and meeting the requirements of the built environment, the higher energy efficiency, the lower building energy consumption. Experiments show that the realizations of system energy consumption model and rated energy efficiency optimization goals can provide an optimization strategy for system energy using equipment in different load operating mode. Working status of control equipment can make the system energy efficiency reach the optimal or near optimal state.4. Introduced the development of building energy management system based on energy efficiency optimization. The system is a typical distributed control system (DCS), according to the building energy-using equipment and work characteristics, introduce the energy efficiency optimization algorithms that this paper researched. The development of the system adopted the self-developed microkernel preemptive embedded operating system, the introduction of operating system has played a positive role for the continued expansion and operational stability of the energy management system functions. So the paper gave a brief introduction to the microkernel operating system. Finally it briefly introduced the engineering application of the building energy management system based on energy efficiency optimization and the energy-saving effect.It can reduce the building load of the building ends by improving building energy use efficiency; we can obtain the equivalent building load with less energy consumption by optimizing energy efficiency of the building energy-using equipment, it has a double role for reducing building energy consumption by improving energy use efficiency and energy efficiency of the building energy-using equipment. The building energy efficiency optimization researched in this paper contains two levels of the optimization: one is the optimization to the energy-using equipment, the other one is the optimization to the building load. Energy using equipment optimized is mainly realized through the control of energy using equipment in building. With the implementation of optimized strategy, reduce the energy consumption of the same building load required. Through energy utilization efficiency algorithms to control the energy use equipment can reduce energy consumption of the end-using equipment and also reduce the corresponding building load. Meanwhile, reduction in building load can further promote the improvement of building energy efficiency.The main innovation points:1. Propose the concept of building energy use efficiency, give the model and calculation method of the building energy efficiency.2. Through the calculation of energy use efficiency, we can do the quantitative evaluation of the effective use of building energy, and provide a quantitative indicator to reduce building energy consumption.3. Propose the system energy efficiency model of the energy-using equipment working in the form of systems, optimization goals and optimization methods of system energy efficiency at different loads. It will effectively reduce the overall system power consumption of the energy-using equipment by implementing system energy efficiency optimization for energy-using.
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