# Adaptive HVAC System Based on Fuzzy Controller Approach
## 4 System Model Implementation
### Generation of FIS Rules
During peak hours, the cost of electricity tends to be higher than the rest of the day because of high energy demand. This is a strategy applied by energy providers to lower their energy loads and avoid power imbalances. ### Energy Consumption

Because thermal comfort was given more consideration in both Scenario 2 and Scenario 3 (see Section 5.2), the controller had to keep the thermostat operating continuously to maintain the desired comfort level. Consequently, HVAC energy consumption increased. Whenever the room temperature reaches the desired comfort level, the thermostat shuts off the compressor for a while before the room temperature deviates from the desired level. This process will continue as long as the occupants are in the space. Figure 12: Scenario 2. Figure 13: Scenario 3. As shown in Figure 14, the HVAC energy consumption is 18.6328 kW for Scenario 1, 32.4284 kW for Scenario 2, and 25.6724 kW for Scenario 3. In comparison with existing approaches [26] (IoFClime), the proposed approach can reduce energy consumption by up to 45% with the help of feedback loop control. ### Impact of Occupancy Variation

This section provides thermal comfort analysis with respect to the varying number of occupants in the conditioned zone using three different established scenarios. The proposed controller's primary goal is to achieve changes in indoor parameters that influence the level of thermal comfort. In this case, the controller is expected to respond to variations in the occupancy number through the feedback loop operation. The interpretation of thermal comfort analysis with respect to the variation of occupancy is presented in Figure 15. This analysis was performed under the same indoor temperature and humidity settings as in Figures 11 and 12. The initial setpoint of 24 \({}^{\circ}\)C was set for 10 occupants. Every five minutes, 10 occupants were added to the zone, and a feedback loop was expected to update the controller with the current state of thermal comfort each time occupants were added. HVAC operation is one of the primary factors that ensure a healthy living environment, which many studies claim can improve occupant productivity at work. This study adopted the Fanger thermal comfort scale to assess the potential of the proposed controller to manage room temperature. Figure 15 represents the analysis of the thermal comfort of the proposed controller examined for three different scenarios (Scenario 1, Scenario 2, and

Figure 14: Comparison of energy consumption under three settings. Figure 15: Analysis of occupant thermal comfort perception for the proposed approach. Scenario 3). In all scenarios, the controller is expected to maintain a room temperature of 19-24 \({}^{\circ}\)C regardless of weather conditions or the number of occupants in the room. The controller was designed to assess thermal conditions and notify the thermostat to increase or decrease HVAC operation through feedback loop control every 30 min. Thermal perception information in Figure 15 indicates that in Scenario 1, 10% of the participants reported normal (comfortable) temperature, 35% of the participants reported a warm temperature, 40% of the participants had no report, and 15% of the participants reported feeling very hot. In Scenario 2, 88% of the participants reported a normal (comfortable) temperature and only 12% reported a warm feeling. Similarly, in Scenario 3, 78% of the participants reported a normal temperature, with only 22% of the participants reporting a warm temperature. Our analysis demonstrates that Scenarios 2 and 3 produced the most satisfactory results, which were within the defined comfort bounds. Conversely, Scenario 1 produced the least satisfactory results. ## 6 Conclusions

Occupancy number and desired comfort level are essential parameters in modeling thermal comfort control, but they are often ignored or inappropriately applied. To attain higher energy savings and satisfactory comfort, the occupancy number and desired comfort parameters must be considered.