Second, the ways and methods of energy saving in the field of HVAC. With the continuous progress of science and technology, new technologies in the field of HVAC are constantly emerging. We can save energy in HVAC system by various methods. 1. Carefully design the HVAC system to make it run efficiently and economically. HVAC system, especially central air conditioning system, is a huge and complex system, and the design of the system directly affects the performance of the system. For example, the system is often designed according to the maximum load, but the actual operation is basically under part load. If the design of each part of the system can not meet the requirements of partial load operation, the energy consumption of the system is very large. For example, the design of fresh air system should be able to change the fresh air volume with the change of outdoor meteorological parameters to minimize the start-up time of the main engine. It can be said that the design of air conditioning system plays an important role in energy saving of the system. 2. Improve the thermal insulation performance of building maintenance structure and reduce cold and heat losses. As we know, for HVAC systems, the air conditioning load through the maintenance structure accounts for a large proportion, and the thermal insulation performance of the maintenance structure determines the comprehensive heat transfer coefficient of the maintenance structure, that is, determines the air conditioning load through the maintenance structure. Therefore, in the national building energy-saving design codes and standards, the primary requirement is to improve the thermal insulation performance of the maintenance structure. 3. Improve the control level of the system, adjust the indoor thermal and humid environment parameters, and reduce the energy consumption of the air conditioning system as much as possible. The effect of air conditioning system, especially comfort air conditioning system, on human body is carried out through the air temperature, humidity, wind speed and average radiation temperature of the environment, and the human body's cold and hot feeling to the environment is the result of the comprehensive action of these environmental factors. In the past, the control mode of air conditioning was only to measure and control the temperature and humidity of the air, even just the air temperature. Obviously, it is not comprehensive, which will inevitably bring many problems, such as the indirect effect of air conditioning system on human body, the slow adjustment of the environment when the environment changes, the discomfort of human body, and the energy-saving adjustment of air conditioning system. The application of the research results of hot and humid environment provides a theoretical basis for us to adopt new control methods. If the comfort evaluation index, that is, the somatosensory index, is used as the control parameter of air conditioning system, such as PMV or SET* index, not only the shortcomings of traditional control methods can be solved, but also energy can be greatly saved. According to our preliminary research, this control method can make the air conditioning system save energy by about 30% under the condition of human comfort. 4. Adopt new energy-saving and comfortable and healthy air conditioning methods. As mentioned above, there are many environmental parameters that affect human thermal comfort. Different combinations of environmental parameters can obtain the same thermal comfort effect, but the energy consumption of air conditioning systems with different combinations of thermal and humid environmental parameters is different. For example, in winter, if the whole indoor air is heated by traditional air conditioners, and the heat and moisture exchange between human body and environment is realized through air, higher air temperature is needed. At this time, the heat loss by maintaining the structure and heating fresh air is relatively large. If we change the traditional air conditioning mode and increase radiant heat (such as low-temperature floor radiant heating) according to the research results of thermal and humid environment, the required air temperature will drop obviously, generally reaching 12~ 14 degrees, while the traditional mode is generally 18~20 degrees. Obviously, the latter has a significant energy-saving effect than the former. Summer has a similar result. 5. Promote the application of air conditioning systems using renewable energy or low-grade energy. With the wide application of air conditioning system, the consumption of non-renewable energy by air conditioning will increase greatly, and the damage to the ecological environment will become more and more serious. How to use renewable energy and low-grade energy has become an important research topic in this field. Ground source heat pump air conditioning system is developed in this situation, which can use the soil heat in the underground constant temperature layer to significantly improve the COP value of the air conditioning system and greatly reduce the energy consumption of the system under the same heating (or cooling) amount. In addition, solar heating or cooling technology is also under development. 6. Carry out the research and application of cold and heat recovery to maximize the use of energy. At present, many researches on cold and heat recovery of air conditioning system are also vigorously carried out, such as the total heat recovery device for exhaust air of air conditioning system, and the supply of sanitary hot water by condensing heat in summer, all of which have recovered the cold and heat of the system and significantly improved the energy utilization rate of air conditioning system. Three. Problems and Countermeasures There are many mature conditions to realize energy saving and consumption reduction of air conditioning system, but there are also many problems to be solved: 1. Design and management of HVAC system As mentioned above, the design of air conditioning system has an important impact on energy saving of air conditioning system. However, in practice, some design departments and designers often do not pay enough attention to it, which makes the system designed and built not only have a large initial investment, but also have amazing energy consumption, which greatly exceeds the national standard. According to the actual measurement, the energy consumption of air conditioning in some public buildings accounts for 60% of the total energy consumption of buildings. Therefore, it is necessary for us to suggest that relevant government functional departments strengthen the management of HVAC design projects, and entrust relevant technical departments, such as the Institute, to strictly examine design drawings and documents, and prohibit design and construction that does not meet relevant national energy-saving standards. 2. Besides the design, we found that the operation management of HVAC system also plays an important role. In some units, the air conditioning system is only turned on and off all the year round, and it is switched between winter and summer. Obviously, the system cannot achieve the corresponding energy-saving effect. Therefore, the operation management personnel are required not only to have a strong sense of responsibility, but also to carry out systematic training and assessment before taking up their posts. Those who fail to meet the requirements should be retrained and can only take up their posts after passing the examination. In the investigation, we found that the energy consumption of different managers in the same system is very different, and some even differ by more than 50%. 3. Development and application of new air conditioning methods, control methods and new energy-saving technologies As mentioned above, adopting new air conditioning methods and new control methods can not only significantly improve thermal comfort, but also greatly save energy of the system. The research on the new mode and control mode of air conditioning in our province can be said to be earlier in the country, and some gratifying results have been achieved. As long as the government departments give a little support, these achievements will soon be applied and industrialized, and the implementation of these projects will greatly promote the energy, environment and economy of our province. 4, the public's understanding of the role of air conditioning system concept for comfort air conditioning system, from a professional point of view, is to make the human body have good thermal comfort. In society, we often find a concept that the colder the air conditioner is in summer and the hotter it is in winter, the better the effect. This obviously runs counter to the starting point of comfortable air conditioning. In fact, this not only greatly increases the energy consumption of air conditioning system, but also reduces the adaptability and immunity of human body to different environments due to the increase of indoor and outdoor temperature difference. All these can change people's ideas through publicity. 5. Development, popularization and application of renewable energy air conditioning system. HVAC systems using renewable energy, such as ground source heat pump air conditioning system and solar refrigeration heating system, have not only remarkable environmental and social benefits, but also remarkable economic benefits (such as ground source heat pump air conditioning system), which should be vigorously developed and popularized. Of course, like any other new technology, these technologies also have some problems (such as ground source heat extraction of ground source heat pump system, etc.). ), these all need further research and improvement, and also need the attention and support of government departments. To sum up, HVAC system plays an important role in building energy conservation. The research, development and application of energy-saving technology is the basis of energy-saving in HVAC system and building system, and the attention and support of government functional departments is the guarantee to realize substantial energy saving, produce remarkable environmental and social benefits and promote economic development.