## 2 Materials and Methods
### Data Collection and Overview  
The inside environmental parameters (temperature, humidity, and radiation) were measured by the sensors in the center of the greenhouse. Temperature and humidity (RS-WS-N01-2, Shandong Jianda Renke Measurement and Control Technology Co., Ltd., Jinan, China) were installed 2 m above the ground, solar radiation was monitored with a radiation sensor (RS-GH, Shandong Jianda Renke Measurement and Control Technology Co., Ltd., Jinan, China), it was also installed 2 m above the ground. The three environmental datapoints were collected in one minute and uploaded to the cloud platform (T-Link, [[https://www.tlink.io/](https://www.tlink.io/)]([https://www.tlink.io/](https://www.tlink.io/)), accessed on 15 July 2020), and 1073 internal environmental parameters and weather environmental data sets were obtained. The average hourly air temperature and air humidity of two greenhouses are shown in Figures 2 and 3. As can be seen in the figures, the air temperature ranges for Greenhouse A and Greenhouse B are between 15 and 50 \({}^{\circ}\)C and from 10 to 50 \({}^{\circ}\)C, respectively. Air humidity ranges for two greenhouses are from 20 to 90% and from 20 to 100%, respectively.  
The current and historical outdoor meteorological parameters were downloaded from the website (www.data.cma.cn/, accessed on 15 July 2020). Outdoor meteorological parameters include atmospheric pressure (P\({}_{\text{a}}\)), sea level pressure (P\({}_{\text{s}}\)), wind direction (WD), wind speed (WS), air temperature (T\({}_{\text{mean,out}}\)), air maximum temperature (T\({}_{\text{max,out}}\)), air minimum temperature (T\({}_{\text{min,out}}\)), air humidity (RH\({}_{\text{out}}\)) and precipitation (P). The value of Pearson's correlation coefficient between the inner environmental parameter of the solar greenhouse and the outdoor environmental parameter of the weather station is shown in Table 1. Of all outdoor variables, T\({}_{\text{mean,out}}\) has the highest positive correlation with the T\({}_{\text{mean}}\) of Greenhouse A followed by T\({}_{\text{max,out}}\) with the correlation 0.86 and 0.83, respectively. The T\({}_{\text{max,out}}\) and T\({}_{\text{min,out}}\) have the highest positive correlation with the T\({}_{\text{mean}}\) of Greenhouse B followed by the T\({}_{\text{mean,out}}\) with the correlation 0.43 and 0.37, respectively. RH\({}_{\text{out}}\) has the highest negative correlation with the temperature of greenhouses A and B. Some of the outdoor parameters might not be directly correlated with the indoor parameters, for example, the P\({}_{\text{a}}\), P\({}_{\text{s}}\), and P have very small correlation with the indoor environmental parameters. To improve the usability of the DL models, partial high-correlation outdoor parameters as well as indoor parameters are used as inputs to the models, including the T\({}_{\text{mean,out}}\), T\({}_{\text{max,out}}\), T\({}_{\text{min,out}}\), and the RH\({}_{\text{out}}\).  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Relation Features**} & \multicolumn{2}{c}{**Greenhouse A**} & \multicolumn{2}{c}{**Greenhouse B**} \\ \cline{2-5}  & **T\({}_{\text{mean}}\)** & **RH** & **T\({}_{\text{mean}}\)** & **RH** \\ \hline P\({}_{\text{a}}\) & \(-\)0.35 & 0.22 & \(-\)0.13 & \(-\)0.05 \\ P\({}_{\text{s}}\) & \(-\)0.37 & 0.25 &