# Research on Real-Time Control Strategy for HVAC Systems in University Libraries
## 3 Experimental Cases
### User Comfort  
In the standard specification GB 50189-2015 [35] \"Design standard for energy efficiency of public buildings\", it is mentioned that the design of air conditioning systems in public buildings should meet the comfort requirements of indoor temperature and humidity. For example, for an air conditioning system with independent control of temperature and humidity, it is necessary to select appropriate dehumidifying methods and temperature sources to ensure that the indoor humidity is within a comfortable range. In addition, GB 55016-2021 [36] \"General code for building environment\" clearly states that the building environment should meet the basic requirements of human health for sound, light, thermal environment, and air quality, including the reasonable control of indoor temperature and humidity.  
To understand the temperature and humidity control of the library HVAC system, an experiment was conducted to detect temperature and humidity data in the user reading area on the first floor of the library.  
Five test points were established in the test area; their locations are shown in Figure 16. The experiment used a TES-1341 electronic breeze meter (Manufacturer: Taiwan Taishi, place of origin: Shenzhen, China) for data measurement, which included wind speed, temperature, relative humidity, and other relevant data. The equipment was positioned on a tripod at a height of 1.5 m above the ground, as shown in Figure 17. The measuring instrument was operated in automatic mode, collecting data at 5 min intervals. According to the comparison principle in Section 4.1, 18 and 21 June and 22 and 23 June were selected for comparison in the experiment. The data were extracted, and the temperature change curve and relative humidity change curve of the test points (A-E) were drawn, as shown in Figures 18-22.  
Figure 16: Equipment test point location.  
As can be seen in the graphs of the data from the individual test points, both the temperature and relative humidity initially rose during the morning hours in original mode. This indicates that the cooling capacity of the unit in this mode was insufficient to meet the demands of the increased library staff and higher outdoor temperatures. However, after retrofitting the HVAC system with an energy-saving mode, the unit was able to provide sufficient cooling capacity to adapt to changes in external factors and meet the temperature requirements of library users. In accordance with GB 50189-2015 [35] \"Design standard for energy efficiency of public buildings\", the indoor temperature of the library building is set at 26 \({}^{\circ}\)C in air conditioning mode. Compared to the original model, the temperature requirements of the library users were not sufficient to meet the demands of the library staff and the indoor temperature requirements of the library users.  
Figure 19: Test point B.  
Figure 17: Electronic breeze meter and tripod.  
indoor temperature after the energy efficiency retrofit is closer to the temperature value set by the specification, thus, creating a good temperature environment for library users more quickly. In GB 55016-2021 [36] \"General code for building environment\", the relative humidity of indoor air should be taken as 60% as the design reference value. According to the data in the figure, the relative humidity value after the energy-saving renovation was closer to the design reference value than in the original mode.  
The comparison of different measurement points revealed variations in temperature and humidity across different regions, which may be attributed to factors such as the  
Figure 21: Test point D.  
Figure 22: Test point E.  
Figure 20: Test point C.  
building's external wall material and exposure to sunlight. This aspect warrants further investigation and potential modifications. By examining the functional use of various regions, as well as considering external wall materials and other relevant factors, adjustments can be made to control the strategies and methods for each specific region.