Energy-saving design of HVAC is the basis of energy-saving of air conditioning and building. The research on HVAC design can not only reduce energy consumption, effectively protect energy and improve the environment, but also improve economic benefits and promote sustainable economic development. Therefore, using the air conditioning design principle and combining with the actual situation, making a reasonable and effective HVAC design scheme can not only improve the effective utilization rate of energy, but also promote the sustainable development of economy. 1 design principle of HVAC 1. 1 basic principle-the most basic principle of energy-saving HVAC is energy saving. In the process of energy-saving design, thermal comfort index is the guidance of practical application. The main influencing factors of thermal comfort index are temperature, air humidity, wind speed, labor intensity and radiation temperature. Explore the combination of the above factors in an appropriate proportion to coordinate comfort and energy saving realistically. The thermal conductivity of the building is properly protected to cope with outdoor climate change and ensure indoor comfort. In addition, the design of pipeline system needs to be simplified, the amount of consumables is reduced and the investment is saved. 1.2 comfortable environment is the main factor to meet the requirements of daily living environment and keep people comfortable. But light, sound and color in daily life are also factors that cannot be ignored. For example, in the indoor environment where people live, warm colors are dominant, which not only reduces the indoor temperature relatively, but also plays an energy-saving role. 1.3 correctly handle the relationship between the whole and the parts. In real life, we live in a collective. By adopting the measures of central heating, not only the energy consumption is reduced, but also the energy utilization rate is improved. In order to meet the different needs of individuals, the following two measures need to be taken: 1) When designing HVAC, the temperature of each room should be controlled independently; 2) Share heat among households. 1.4 controlling indoor air quality and large ventilation is the design trend of HVAC, and solving air quality is the most important problem. Therefore, reasonably exhausting and inhaling indoor airflow and improving indoor air quality not only ensure indoor air quality, but also achieve the purpose of energy saving. 2 Ways and methods of energy saving 2. 1 Improving the HVAC system of building envelope accounts for a certain proportion of air conditioning load in the maintenance structure. The comprehensive heat transfer coefficient of envelope is directly affected by the thermal insulation performance of envelope, and it also changes the air conditioning load. Therefore, in the newly promulgated building energy-saving design standards and codes, the thermal insulation performance of HVAC is the first problem to be solved in the regulations. In order to reduce the cold and heat load of the envelope, it can be achieved by increasing the thermal insulation performance of the roof and wall. For example, the latest wall has skill effect, which helps to reduce the load of the building. The thermal conductivity of this kind of wall is more than twice that of the traditional wall. In the thermal test of the building envelope of authoritative organization, according to the results, the loss of indoor heat caused by doors and windows is between 40% and 50%. Therefore, it is necessary to do a good job in sealing, heat preservation and energy saving measures for doors and windows. 2.2 Reduce the impact of fresh air volume of air conditioning. Fresh air is the key part of energy saving. Excessive air volume will increase the load and power consumption; If the air volume is too small, it will affect the quality of the surrounding environment. Therefore, in order to save energy, it is necessary to adjust the fresh air ratio and supply air temperature. For example, in the spring and autumn transition season, air-conditioned rooms do not need heating or cooling, and fresh air can be used. In winter and summer, the outdoor fresh air volume should be controlled as small as possible. 2.3 Using frequency conversion technology to reduce energy consumption Choosing a reasonable air conditioning method can effectively reduce energy consumption. In recent years, frequency conversion air conditioning has developed rapidly, which not only saves energy, but also has good indoor comfort. In air-conditioning stores in Japan, the sales of inverter air conditioners account for nearly 90% of the total. According to Japanese standards, inverter air conditioners are more energy-efficient than ordinary air conditioners in most seasons. If the cooling load is the same, the inverter air conditioner can save energy by 34% compared with the fixed frequency air conditioner. Therefore, variable frequency air conditioning will be the development direction of air conditioning in the future, with outstanding energy-saving effect. The application of frequency conversion technology in central air conditioning is mainly reflected in two aspects: 1) replacing the original regulating valve with variable speed fan and variable speed pump to reduce energy consumption and improve efficiency; 2) The water flow rate is changed according to the load of air conditioner by variable flow rate, so as to achieve the purpose of energy saving. 2.4 Strengthen the cold and hot cycle to improve energy utilization. In today's society, the cold and hot recycling of air conditioners has been widely concerned and popularized. For example, in summer, the utilization of sanitary hot water and the application of total heat recovery device in air conditioning. Various measures have improved the utilization rate of energy recovery. At present, it has become a new trend to transfer excess energy in the system to the needed part. The total heat exchanger improves the energy utilization rate, which can reach 75% ~ 80%. In air conditioning systems, energy recovery equipment, such as heat exchangers, such as recovery circuits, can also be used. Statistics show that the heat pump system is the most commonly used and can recover energy below 1 10℃. As for heating materials, low-temperature heat sources and natural environment can be fully utilized. This energy-saving technology is new and efficient. If the heat pump and recovery equipment are used together, the energy saving effect is better than that of a single equipment. Conclusion With people's concern about environmental pollution, people pay more and more attention to the concept of low carbon, and the slogan of building a conservation-oriented society reflects China's attention to environmental pollution. Therefore, HVAC designers pay more and more attention to the energy-saving design of air conditioning system, and adopt a series of measures and technologies in the design process. These measures and technologies can only improve the utilization rate of energy within a certain reasonable range, avoid unnecessary energy waste, and promote the utilization of energy in all aspects. Save energy according to local conditions, take different energy-saving measures according to different natural environments, and make full use of the local natural environment. In the investigation of HVAC industry, it is found that the energy-saving measures adopted by the existing air conditioning system can save energy by more than 50% at most. The popularization and application of energy-saving technology not only effectively reduces energy consumption, but also improves environmental pollution and effectively protects natural resources, which is of dual significance to society and nature, promotes economic revitalization, and is also an inevitable trend of social development.

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