# Research on Thermal and Heat Insulation Properties of Aerogel Heat-Insulating Reflective Coatings
## 3 Data Analysis
### Characteristic Data Analysis  
As defined in the Code for Thermal Design of Civil Buildings [23], the decay multiplier and time delay were calculated for all three samples. The time delay and decay multiplier reflect the thermal storage capacity of the material. A material's thermophysical properties and thickness determine its different time delays and decay multipliers. A high time delay and low attenuation multiplier for a building wall indicate that the wall has excellent thermal storage capacity. When the external environment fluctuates to a certain extent, a wall with a high time delay and low attenuation multiplier can ensure a stable indoor temperature. The Thermal Design Code for Civil Buildings expresses the formula for both. Figure 4: Temperature variation curves of test pieces for working Condition 1: (**a**) blank board temperature variation; (**b**) aerogel board temperature variation; (**c**) XPS board temperature variation; (**d**) cold side air temperatures of three specimens. Figure 5: Temperature variation curves of test piece for working Condition 2: (**a**) blank board temperature variation; (**b**) aerogel board temperature variation; (**c**) XPS board temperature variation; (**d**) cold side air temperature of three specimens. Table 2 presents data comparing the thermal insulation performances of blank specimens with aerogel and XPS boards under two working conditions. \[\text{f}=\frac{T_{cold}^{max}-T_{cold}^{min}}{T_{hot}^{max}-T_{hot}^{min}} \tag{1}\]  
\[\emptyset=t_{cold}^{max}-t_{hot}^{max} \tag{2}\]  
where f is the damping factor, \(T_{cold}^{max}\) is the maximum value of the ambient temperature in the cold box, \(T_{cold}^{min}\) is the minimum value of the ambient temperature in the cold box, \(T_{hot}^{max}\) is the maximum value of the ambient temperature in the hot box, and \(T_{hot}^{min}\) is the minimum value of the ambient temperature in the hot box; \(\emptyset\) is the time log, \(t_{hot}^{max}\) is the time corresponding to the time when the ambient temperature inside the hot box reaches its maximum value, and \(t_{cold}^{max}\) is the time corresponding to the time when the ambient temperature in the cold box reaches its maximum value. During the heating phase of Condition 2, fluctuations in the test data curve occurred due to the influence of the test environment on the air temperature at the hot end. In Condition 2, errors may have arisen in calculating the decay multiplier and time delay because of data points with the same temperature value. This is documented in reference [24]. The calculation results for Condition 1 show that the XPS insulation board increased the time delay of the blank board by a factor of seven, which is of great significance in maintaining a stable room temperature. From the data, it can be concluded that the thermal insulation efficacy of the aerogel coating is far from that of the XPS insulation board. Still, it is worth noting that the thickness of the aerogel coating is 1 mm. In contrast, the thickness of the XPS insulation board is 2 cm, thus showing that the application of aerogel coating to the insulation and thermal insulation of building facades will be a disruptive development. Comparing the calculated decay multiplier and time delay results for the aerogel and XPS boards, it has been discovered that the use of aerogel coating has a minimal impact on the thermal insulation capability of the blank board. The effect of XPS on the blank boards was more intuitive, as it related to the thickness of the test specimens, the test environment, and the material properties [25]. The decay multiplier and time delay, in combination with the temperature change curve and the temperature difference distribution in the final steady state, also confirm the different specimen insulation capacities from another perspective. Figure 6 shows the temperature field distribution of each specimen during the warming and stabilization phase.