# Service Life Prediction and Life Cycle Costs of Light Weight Partitions
## 4 Field Survey Results and Discussion
### Service Life Expectancy and Performance Level under Standard Conditions  
A statistical analysis was conducted of each sample, which included fitting a regression line and formulas, determining the prediction interval, and calculating the predicted service life expectancy in standard deterioration conditions. Additionally, prediction interval boundaries for the expected behavior of the partition were established with a statistical probability of \(p=0.80\), as required by ISO 15686 [21]. To calculate the predicted life expectancy of the components, a minimum required component performance level (MRCP) of 60% was determined (MRCP\({}_{60\%}\)), reflecting the component's advanced deterioration and necessitating its complete rehabilitation. The partition's predicted service life expectancy (SLE) is determined by where the MRCP\({}_{60\%}\) line meets the TDP regression line, given specific occupancy conditions (\(\mu\)). The range of years for expected performance (PSLI) is set by the prediction interval (PI) with an 80% statistical probability. The PI intersections provide the probable upper and lower performance levels (PCPI) for a specific component age. It should be noted that because the age range of the survey components does not exceed 30 years, most intersections occur outside the range examined in the field survey. Table 4 summarizes the analysis results of each partition type. In referring to the prediction interval boundaries established for gypsum board partitions, we see the partitions are only expected to exceed the range of 50 years (average service life expectancy of 95 years) in light service conditions (\(\mu=0\)). As the number of negative occupancy factors increases, the average service life expectancy decreases to 47, 27, and 11 years, respectively. At levels of \(\mu\) greater than 2, it can be expected that, for a component lifespan of about 25 years, the functional range will fall below the desired minimum performance level of MRCP\({}_{60\%}\). This last finding means that partitions of this type are not suitable for situations of occupancy conditions with \(\mu\) greater than 2; that is, gypsum board partitions are not suitable for harsher than average occupancy conditions. \begin{table}
\begin{tabular}{l c c c c} \hline \hline \multirow{2}{*}{**Occupancy Conditions**} & **Light** & **Moderate** & **Standard** & **Intensive** \\ \cline{2-5}  & \(\mu\) **= 0** & **1** \(\leq\mu\) **\textless{} 2** & **2** \(\leq\mu\) **\textless{} 4** & \(\mu\geq 4\) \\ \hline \hline \multicolumn{5}{l}{**Gypsum board**} \\ \hline Service life prediction MRCP60\% [years] & 95 & 47 & 27 & 11 \\ Expected service life interval MRCP60\% [years] & 101–89 & 51–43 & 29–24 & 16–6 \\ Component performance interval expected at 20 years & 94–90 & 86–79 & 72–65 & 47–18 \\ Component performance interval expected at 25 years & 92–88 & 81–75 & 66–59 & 33–3 \\ \hline \hline \multicolumn{5}{l}{**Autolcaled Concrete Blocks**} \\ \hline Service life prediction MRCP60\% [years] & n/a & 72 & 32 & 18 \\ Expected service life interval MRCP60\% [years] & n/a & 78–66 & 35–29 & 23–13 \\ Component performance interval expected at 20 years & n/a & 88–84 & 76–70 & 65–47 \\ Component performance interval expected at 25 years & n/a & 86–81 & 71–64 & 57–38 \\ \hline \hline \multicolumn{5}{l}{**Hollow Concrete Blocks**} \\ \hline Service life prediction MRCP60\% [years] & 164 & 118 & 86 & 38 \\ Expected service life interval MRCP60\% [years] & 174–156 & 125–111 & 95–77 & 45–31 \\ Component performance interval expected at 20 years & 96–95 & 93–89 & 90–84 & 82–70 \\ Component performance interval expected at 25 years & 94–93 & 91–87 & 88–82 & 78–65 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Service Life Predictions at a Minimum Required Component Performance Level of 60% (MRCP\({}_{60\%}\)); Component Performance Intervals for Various Partitions in Different Occupancy Conditions. For autoclaved blocks, the SLE is projected at 72 years in moderate occupancy conditions, and reduces to 18 years in more intensive scenarios.