# The Impact of Internal Insulation on Heat Transport through the Wall: Case Study
## 3 Results and Discussion
### Measurements of Temperature and Heat Flux
In order to ensure good quality of the carried out measurements, proper thermal contact of the connection between the heat meter and the outer wall surface was ensured by the use of conductive adhesive contact paste. Parallel to the measurement of heat flux density, air temperature was measured on both sides of the wall using temperature sensors contained in the measurement setup. The results were recorded in hourly time steps. The second measurement was taken at the same place after the wall had been insulated from the inside. The carried out measurements demonstrated a significant difference in the value of thermal transmittance of the outer wall in relation to the calculation results (Table 4). The calculations based on the data contained in the archival project documentation carried out in line with the methodology ISO 6946: 2017 [41] demonstrated that thermal transmittance of the wall in question was \(U=1.40\) W/m\({}^{2}\)K. The tests carried out before wall insulation allowed us to determine the actual value of thermal transmittance. The measurement with the use of a heat flux sensor showed that thermal transmittance was \(U=2.37\) W/m\({}^{2}\)K. The tests carried out after the application of thermal insulation, which was 0.06 m thick and had thermal conductivity coefficient of \(\lambda=0.042\) W/mK, demonstrated that thermal transmittance decreased to the level of \(U=0.56\) W/m\({}^{2}\)K. This value is higher by 0.09 W/m\({}^{2}\)K as compared to the calculated thermal transmittance (Tables 1 and 2). The heating system in the room was made with the use of panel radiators. The heat source was located in the local gas boiler room. Thermographic measurements were taken during the semester break, when the temperature of the internal air decreased. The first measurement was made at the beginning of this period, for the temperature of +19.3 \({}^{\circ}\)C. The outside air temperature was 2.7 \({}^{\circ}\)C. The next measurement after the completion of thermal insulation works was carried out at a lowered internal air temperature of 17.0 \({}^{\circ}\)C and lowered external air temperature of \(-2.5\)\({}^{\circ}\)C.  
The use of thermal insulation from the inside of the wall also has a significant impact on the microclimate in the room. The measurement results of the indoor air temperature, humidity, and dew point temperature are presented in Figure 8.  
The measurement frequency was one measurement per hour. Stabilized results were accepted for the presentation of results. The diagrams demonstrate principally a significant change of indoor air humidity. After the application of internal insulation, the relative humidity measured around the corner of the outer walls definitely decreased. It is related to the moisture level of wall substrate. By the use of a thermal insulation layer with high water vapor permeability, the excess water vapor contained in the air was absorbed by the thermal insulation layer. The results are collected in Tables 5 and 6. \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **Air Temperature [\({}^{\circ}\)C]** & **Air Humidity [\%]** & **Dew Point [\({}^{\circ}\)C]** \\ \hline
**Min** & 16.6 & 41.5 & 3.0 \\
**Max** & 17.4 & 44.3 & 4.2 \\
**Average** & 16.9 & 43.2 & 4.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Indoor microclimate after the application of insulation. Measurement taken from 17 February 2018 to 18 February 2018.