## 3 Results and Analyses
### DesignBuilder Simulation Analysis
#### 3.4.2 Thermal Environment Simulation  
The thermal environment simulation also selected the same two days as the light environment simulation (5 January 2002 in winter and 29 July 2002 in summer) to conduct the indoor temperature field and thermal environment simulation. The temperature cloud map and the indoor and outdoor temperature change curves in winter and summer are shown in Figures 9-12.  
As outdoor temperature is easily affected by weather conditions (the outdoor temperatures of this simulated weather model were 11.1-16.8 \({}^{\circ}\)C, and the actually measured outdoor temperatures were 22.3-29.2 \({}^{\circ}\)C), the temperature simulation was only used for temperature change law analysis. According to the temperature cloud map of the photovoltaic greenhouse in winter (Figure 9), the distribution law of the temperature in the photovoltaic greenhouse in winter was as follows: the temperatures on the south and west sides were higher than those on the east and north sides; the distribution of the temperature of the vertical plane gradually reduced from high to low, but the ground temperature was slightly high.  
The temperature change curves in photovoltaic greenhouse in winter (Figure 10) showed that the indoor and outdoor temperature difference reached the maximum at 13:00 (approximately 1 \({}^{\circ}\)C), the indoor relative humidity reduced with the increase of temperature and the highest temperature and the lowest relative humidity appeared at about 15:00. The measured indoor and outdoor temperature and humidity change trends were basically the same as the simulated data. However, the measured data were easily influenced by the weather, and the indoor temperature became lower than the outdoor temperature after 16:00.  
Figure 9: Temperature simulation cloud in the photovoltaic greenhouse in winter.  
According to Figure 11, the temperature was even in most of indoor areas, with the wall and the vent being a little higher and the ground being a little lower. This is mainly because the prevailing wind direction of the local area in summer was southeastern. The south elevation of the greenhouse was the windward side, and the serrated vent on the north side had a negative pressure. Hence, the internal heat normally accumulated at the serrated vent and the lower part of the wall. During the simulation, the northern serrated vent had a larger range of high temperature than the two serrated vents on the south side. This is because the area was also covered with a shading net, except for the insect-proof screen, which would reduce the venting ability of the area and affect the discharge of hot air.  
According to Figure 12, the indoor relative humidity changed with the increase of temperature. The highest temperature and the lowest humidity appeared at about 13:00.  
Figure 11: Indoor temperature simulation cloud of the photovoltaic greenhouse in summer.  
Figure 10: Temperature and humidity change curves of the photovoltaic greenhouse in winter.  
The indoor temperature was slightly lower than the outdoor temperature before 9:00 and was higher than the outdoor temperature during 9:00-15:00. The two temperatures were close during 15:00-17:00. This trend was basically the same as the measured results. However, the temperature difference of the measured data was about 2 \({}^{\circ}\)C higher than that of the simulated data, and the temperature rise was 1 h earlier than the simulation. This had a certain relationship with the actual wind speed, the weather condition, and the environment during the test day.