# An Automated IoT Visualization BIM Platform for Decision Support in Facilities Management
## 2 Research Methodologies and Experimental Design
### Experimental Design
#### 2.2.3 Dynamo Automation Platform  
This study used Dynamo to establish a temperature and humidity data automation platform. Arduino microcontrollers were employed to collect temperature and humidity data in the classroom. The transmission interface established by this platform performed data processing and color spatial visualization, and it could automatically input data into the BIM model. The platform was established employing the following four steps:  
1. Use the Firefly suite to create a node linking Dynamo and Arduino, forming a basis for interactive prototyping and importing environmental data into Dynamo (see Figure 7). 2. The interpolation method was used to calculate the value of each grid square, as shown in Figure 8. The visualization components of the context view index and the RGB color rendering values of the grid squares are as shown in Figure 9.  
Figure 6: **(a) Arduino Mega 2560 R3; (b) Arduino connection to DHT-11 temperature and humidity sensor. **  
Figure 7: Arduino and Dynamo linking process. 3. The code fragments first create a layer component in BIM at the predefined elevation, collect sensor data and calculate the context view index (PMV) for each grid in the layer using interpolation, and then paint the corresponding color for each grid based on the predefined color palette scheme. The result of this step creates a thermography-like image and allows a user to visually see the distribution of the desired context view index value of the space in BIM (see Figure 10). Figure 8: Calculation of grid data by interpolation. Figure 9: Grid data and RGB conversion. 4. Decisions concerning the indoor comfort pointer are based on predicted mean vote (PMV), and the results of analysis can be presented in the BIM model on this platform as shown in Figure 11. Note that PMV is a common metric for assessing the comfort level of an indoor environment, and has been adopted in ISO 7730 [25]. The PMV formula used in this study is shown in Equations (1)-(4). When PMV = 0, the indoor environment is in the best thermal comfort state [26]. According to ISO 7730, an ideal PMV value is between \(-0.5\) and \(+0.5\)[25]. PMV can be calculated based on factors including the body's metabolic rate and clothing insulation, as well as environmental parameters (air temperature, average radiant  
Figure 11: PMV analysis and improvement suggestions. Figure 10: Adaptive components and addition of a plane in the Revit process diagram. temperature, relative air velocity and humidity). As illustrated in Figure 12, a PMV formula can be written in Python and nested in Dynamo to create a node for reading the PMV. \[ \begin{split}\text{PMV}=[1.303\exp(-0.306\,M)+0.028]\ \{(M-W)-3.05\times 10^{-3} \times[5733-6.99(M-W)-P_{a}]-\\ 0.42[(M-W)-58.15]-1.7\times 10^{-5}\text{M}(5867-P_{a})-0.0014\text{M}( 34-t_{a})-3.96\,10^{-8}f_{cl}\ [(t_{cl}+273)^{4}-\\ (t_{r}+273)^{4}]-f_{cl}\ h_{c}\ (t_{cl}-t_{a})],\end{split}  \tag{1}\]  
where  
\[t_{cl}=35.7-0.028(M-W)-I_{cl}\{3.96\,10^{-8}f_{cl}[(t_{cl}+273)^{4}-(t_{r}+273 )^{4}]+f_{cl}\ h_{c}(t_{cl}-t_{a})\}, \tag{2}\]  
\[h_{c}=\left\{ \begin{array}{ll}2.38(t_{cl}t_{a})^{0.25}&\text{for}\ 2.38 \cdot|t_{cl}t_{a}|^{0.25}>12.1\sur a\\ 12.1\sur a&\text{for}\ 2.38\cdot|t_{cl}t_{a}|^{0.25}<12.1\sur a\end{array}  \right., \tag{3}\]  
\[P_{a}=RH\times 610.6e^{\frac{17.260\text{m}}{273.3+1\text{m}}}. \tag{4}\]  
\(M\): metabolic heat rate, ranging from 46 to 232 (W/m\({}^{2}\));  
\(W\): effective mechanical power (W/m\({}^{2}\));  
\(I_{cl}\): clothing insulation (m\({}^{2}\)K/W);  
\(f_{cl}\): clothing surface area factor;  
\(t_{cl}\): clothing surface temperature (\({}^{\circ}\)C);  
\(t_{a}\): air temperature (\({}^{\circ}\)C);  
\(h_{c}\): convection heat transfer coefficient (W/m\({}^{2}\)K);  
\(t_{r}\): mean radiant temperature (\({}^{\circ}\)C);  
\(v_{a}\): relative wind speed (m/s);  
\(P_{a}\): water vapor partial pressure (Pa);  
\(RH\): humidity (%).