## 3 Analyses of Environmental Parameters of Different Modular Wall Greenhouses
### Temperature Analysis inside the Greenhouses during the Test Period
This indicated that both SG and PG could provide a large amount of heat during the nighttime exothermic process, and the exothermic duration of PG was slightly longer than that of SG. That is, the greenhouse temperature performance in PG was slightly worse than that in SG, so it needed a longer duration of exothermic heat to maintain the greenhouse temperature. In conclusion, the temperature performance of SG was better than that of PG. Comparative Analyses of the Temperature and Humidity of the Air Inlet and Outlet in the Greenhouse on Typical Cloudy Days  
For typical cloudy weather (24 February 2021 9:00 to 27 February 2021 9:00), the temperature and humidity changes of SG and PG air inlet and outlet are shown in Figure 7. The maximum temperatures of both SG and PG were not over 20 \({}^{\circ}\)C. Meanwhile, the fan was set to start when the indoor temperature exceeded 22 \({}^{\circ}\)C during the daytime period (9:00-17:00). Thus, the fans in SG and PG were shut down in cloudy weather. The maximum and minimum temperature of SG greenhouse air inlet was 17.23 and 11.79 \({}^{\circ}\)C, while the maximum and minimum temperature in the air outlet was 19.65 and 11.20 \({}^{\circ}\)C, respectively. The maximum and minimum temperature of PG greenhouse air inlet was 16.63 and 10.98 \({}^{\circ}\)C, while the maximum and minimum temperature in the air outlet was 19.18 and 9.88 \({}^{\circ}\)C, respectively. The average temperature difference between the inlet and outlet was 2.89 and 3.90 \({}^{\circ}\)C. At night, the average relative humidity difference between the inlet and outlet of SG and PG was 19.92% and 15.87% with the fan manual working, respectively. According to the average temperature difference between the inlet and outlet at night, PG could cool quickly. The average relative humidity difference SG was large, which indicated that it had a more obvious enhancement in the indoor air temperature of SG. On the basis of the above results, the average indoor air temperature of SG and PG was 12.03 and 11.92 \({}^{\circ}\)C during the daytime and 11.39 and 11.38 \({}^{\circ}\)C at night, respectively. Meanwhile, the average outdoor air temperature during the daytime was 3.42 \({}^{\circ}\)C and the average outdoor air temperature at night was 2.27 \({}^{\circ}\)C. In summary, thermal insulation and heat storage effect of SG were slightly better than that of PG, and both greenhouses could effectively improve the thermal environment inside the greenhouse under the condition of a cloudy day. The Significance Analyses of Environmental Parameters of Two Greenhouse on Typical Sunny and Cloudy Days  
Significance tests using SPSS software were conducted for SG and PG. The independent sample \(t\)-test was used for both subjects, where ventilation was continuous for 4 h (active thermal storage circulation system was turned on) on typical sunny days. For typical cloudy days, the inlet and outlet temperatures and humidity of both greenhouses are shown in Tables 4 and 5. As shown in Tables 4 and 5, there was a significant difference between the inlet and outlet temperatures on a typical sunny day. However, there was no difference in the relative humidity. Besides, there was a significant difference in the inlet and outlet temperatures and humidity on a typical cloudy day. density of SG and PG was 15.78 and 9.62 W\(\cdot\)m\({}^{-2}\) and the heat storage duration was 2.33 and 2.00 h, respectively. The average exothermic heat flow density of SG and PG was 7.87 and 6.26 W\(\cdot\)m\({}^{-2}\), respectively. The average heat flow density of SG and PG was 7.87 and 6.26 W\(\cdot\)m\({}^{-2}\), respectively, and the duration of heat release was 16 h. This showed that the heat flow density of the back wall of the two greenhouses varied with the time of insulation uncovering, and the average heat storage density of SG was higher than that of PG on sunny days.