Commonly Used HVAC Terms and Explanations Part 3

14. Energy efficiency ratio: The energy efficiency ratio of an air conditioner is the ratio of cooling capacity (heating capacity) to operating power. That is, the mathematical expressions of EER and COP: EER=cooling capacity/cooling power consumption. COP=heating capacity/heating power consumption. The higher the EER and COP, the lower the energy consumption of the air conditioner and the higher the performance ratio. 2.6～2.8 level five, 2.8～3.0 level four, 3.0～3.2 level three, 3.2～3.4 level two, 3.4 and above is level one. Level 1 is the most energy-efficient, Level 5 is the lowest, and products below Level 5 are not allowed to be marketed. Air-conditioning companies need to affix energy efficiency labels on their products to inform consumers of their energy efficiency levels.

15. Vertical imbalance: In the hot water double-pipe system, due to the difference in height between the radiators of each layer and the boiler, although the temperature of the supply and return water entering and flowing out of the radiators of each layer is the same (the influence of cooling along the pipeline is not considered). However, the radiator with a large distance from the boiler has a large pressure, and the radiator with a small distance has a small pressure. Even if different pipe diameters are selected, the resistance balance of each layer cannot be achieved, and there will be uneven distribution of flow between the upper and lower layers, and uneven heating and cooling, which is usually called vertical imbalance. Moreover, the more floors there are in the building, the greater the pressure difference between the upper and lower floors, and the more serious the vertical imbalance will be.

16. Design heat load of the heating system: The design heat load of the heating system is the heat supplied to the building per unit time in order to meet the indoor temperature requirements and maintain the heat balance of the room at a certain outdoor temperature. The design heat load Q′ of the heating system includes two parts: one part is the heat consumption Q1′ for maintaining the structure heat transfer. That is, the heat lost from indoor to outdoor through building doors, windows, floors, roofs and other maintenance structures. The other part is the cold air infiltration heat consumption Q' of heating the cold air infiltrated into the room through the gap of the door and window and the cold air intrusion heat consumption Q' of heating the cold air entering the room due to the opening of the door and window.

17. Calculated indoor air temperature: The calculated indoor air temperature generally refers to the average temperature of the environment in the area where people are active within 2.0m from the ground, which should meet the technological requirements of human life and production.

18. Lower limit thermal resistance (minimum heat transfer resistance): specifically refers to the lower limit value of the heat transfer resistance of the enclosure structure that is allowed to be used in design calculations. The purpose of specifying the minimum heat transfer resistance is to limit the excessive heat transfer through the enclosure structure, prevent condensation on the inner surface, and limit the excessive radiation heat exchange between the inner surface and the human body, which will cause the human body to suffer from cold.

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