## 4 Results and Discussion
### Results
#### 4.1.2 Comparison of Economic Performance: Low and High Usage of Kindergarten  
The economic evaluation employs LCC methodologies to provide detailed insights into the long-term financial impacts of the renovation measures. By capturing data on the building's economic performance, the assessment ensures a robust and holistic understanding of its energy systems. The findings validate the renovation strategy, demonstrating that the kindergarten remains energy-efficient and economically viable throughout its lifecycle. To further analyze cost-effectiveness, the evaluation incorporates two distinct schemes:  
* Net metering--where exported energy offsets imported energy on a 1:1 basis;
* Net billing--where exported energy is valued at a lower rate than imported energy. Both schemes were examined under various reconciliation periods: yearly, quarterly, monthly, and daily, allowing for a detailed comparison of their economic performance under differing operational conditions. Table 10 summarizes the economic outcomes of the kindergarten's energy upgrade for both the low-usage and high-usage scenarios, including the case with a smaller PV system under high-usage conditions. This combined analysis provides a comprehensive perspective on the financial performance and cost-effectiveness of the implemented energy measures, particularly focusing on the PV system installation and its impact across varying system sizes and operational conditions. The results from Table 10 highlight significant differences in economic performance between the net metering buyback and net billing buyback schemes across all usage scenarios, with variations becoming more pronounced as reconciliation frequency shortens. Under net metering, surplus energy offsets imported energy costs on a 1:1 basis, resulting in better economic outcomes, especially with yearly reconciliation. In high-usage scenarios, shorter reconciliation intervals (e.g., daily) increase LCC and WLC by 17.6% and 22.6%, respectively, compared to yearly intervals. In contrast, net billing, which values exported energy at a lower rate, shows smaller cost variations with shorter intervals, achieving slightly lower LCC (0.4%) and a 3.5% shorter payback period under daily reconciliation compared to net metering. These results highlight net metering's advantage in long intervals and net billing's stability with shorter intervals. In the low-usage scenario, net metering outperforms net billing due to its reliance on surplus energy exports, which directly offset costs. Yearly reconciliation under net metering results in shorter payback periods and lower WLC compared to daily reconciliation, while net billing sees higher LCC and extended payback periods as surplus energy is undervalued. These findings emphasize net metering's advantage in low-demand settings, where it achieves greater savings than net billing. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline
**Net** & **Life Cycle** & **Annual Avg. ** & **While Life** & **Annual Avg. ** & **PV Payback** & **Net Billing** & **Life Cycle** & **Annual Avg. ** & **While Life** & **Annual Avg. ** & **PV Payback** \\
**Meeting** & **Costs (ICCC,** & **ECC** & **Cycle Costs** & **WLC** & **Period** & **Replay** & **Costs (ICCC,** & **ECC** & **Cycle Costs** & **WLC** & **Period** \\
**Buyback** & **EUR)** & **(EUR)/year** & **(WLC, EUR)** & **(EUR/Year)** & **(EUR)** & **(EUR)** & **(EUR)/year** & **(EUR)** & **(EUR/Year)** & **(EUR  
In the high-usage scenario with a smaller PV system, both net met metering and net billing result in significantly higher costs and longer payback periods due to reduced energy generation. For daily reconciliation, net metering shows a 48.2% increase in LCC and a 61.4% longer payback period compared to yearly reconciliation, while net billing exhibits similar trends with slightly shorter payback periods (1.7% lower) across all intervals. However, WLC remains consistently higher for shorter reconciliation periods, underscoring the inefficiencies of balancing energy production and demand over smaller intervals.