# Adaptive HVAC System Based on Fuzzy Controller Approach
## 4 System Model Implementation
### Generation of FIS Rules
The three scenarios include (a) when the occupants are concerned about the cost of energy usage and are keen to engage in the demand control strategy; (b) when the occupants are concerned with comfort requirements and are willing to bear the cost of electricity at any hour of the day; and (c) when the occupants try to balance comfort and energy usage and are willing to compromise the comfort level when the energy tariff is at its peak rate. A temperature of 24 \({}^{\circ}\)C is within the acceptable indoor comfort level and is chosen as the initial setpoint throughout the experiments. Note that the temperature values used in the figures are in degrees Celsius throughout the study. Similarly, the study adopts ASHRAE Standard 55 for Thermal Environmental Conditions for Human Occupancy throughout the study [60]. Figure 10 represents the hourly indoor temperature in Johor Bahru, Malaysia. From 8:00 a.m. to 9:00 a.m. and from 4:00 p.m. to 8:00 p.m., the temperature was \"hot.\"From 9:00 p.m. to 11:00 a.m. and from 3:00 p.m. to 4:00 p.m., the temperature was considered \"very hot.\" \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Properties** & **Material** & **c (J/Kg-K)** & **(W/m-K)** & **Thickness (cm)** \\ \hline \multirow{4}{*}{Wall} & Tuff & 650 & 1.5 & 10 \\  & Brick & 1000 & 0.11 & 18 \\  & Polystyrene & 1600 & 0.028 & 8 \\  & Concrete & 650 & 0.43 & \\  & Stoneware & 650 & 1.25 & 1.3 \\ Ground Floor & flooring & 650 & 0.07 & 8 \\  & Igloo & 650 & 1.1 & 1 \\  & Gravel & 650 & 1 & 5 \\  & Screed ordinary & 650 & 0.7 & 25 \\  & concrete & 650 & 0.4 & 8 \\ Ceiling & XPS polystyrene & 650 & 0.4 & 8 \\  & panel & & & \\  & Bricks stuff & 650 & 0.5 & 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: The thermal properties and thicknesses of the building materials. Figure 11 represents the state of indoor temperatures from 8:00 a.m. to 5:00 p.m.. The goal of the controllers is to bring the room temperature to a satisfactory level under the initialized temperature (24 \({}^{\circ}\)C). The operation patterns indicate that both the existing and proposed controllers achieved fairly cool room temperatures except during peak energy demand periods. One of the reasons is that the occupants were worried about the cost of energy during these hours. In this setup, the feedback loop control did not show any impact during these hours, causing a predicted percentage of dissatisfaction (PPD) of 20% and 37% at 24.9 \({}^{\circ}\)C and 25.8 \({}^{\circ}\)C, respectively. Similarly, to maintain a healthy comfort level, no room should go beyond 20% PPD. The pattern of indoor temperature control in the second scenario is the same as the state of the first scenario for the existing method, while the proposed approach reflects excellent temperature control during very hot periods, as indicated in Figure 12. This indicates that the proposed approach can manage indoor comfort through feedback loop control, resulting in an overall minimum and maximum PPD of 4.4% and 10% occurring at 24.1 \({}^{\circ}\)C and 24.3 \({}^{\circ}\)C, respectively, keeping indoor comfort satisfactory. One of the limitations of the existing approaches [26; 52; 57; 58] is the lack of feedback loop control to respond to undesired comfort situations, especially in the afternoon when the temperature is not stable. Figure 11: Scenario 1. Figure 10: Temperature from 8:00 a.m. to 5:00 p.m.

As can be seen in Figure 13, from 11:00 p.m. to 3:00 p.m., the temperature was \"extremely hot.\" However, the proposed controller brought the temperature down as much as possible to ensure a satisfactory comfort level while accounting for the cost of energy consumption. Similarly, in the third scenario, unlike the existing approach, the proposed approach reflects moderate temperature adjustment during very hot and extreme hours. This indicates that the proposed approach can manage indoor comfort levels through a feedback loop according to the state of the electricity tariff (see Figure 13).