## 6 Discussion
### Emission Reduction by Region  
#### 6.1.1 Flexible Start  
When evaluating the Flexible Start algorithm for a fixed duration between 6 and 24 h, [PERSON] et al. [9] found significant emissions reductions for shorter jobs (e.g., the DenseNet experiments), with minimal savings for jobs longer than one day. In our experiment, we can confirm this observation: by looking at Table 3, we see that our longest workload (i.e., HF-SCA, lasting 16 h) achieves a maximum average of 2.80%, while shorter workloads reach 6-7%. At first glance, the size of this decrease seems much smaller: Dodge  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Strategy** & **Avg Time Dilatation** & **Std Time Dilatation** & **Avg Carbon Reduction** \\ \hline Flexible Start & 7:54 h & 2:46 h & 5.72\% \\ Pause \& Resume & 11:15 h & 3:26 h & 6.51\% \\ \hline \hline \end{tabular}
\end{table}
Table 4: Quantitative comparison between strategies.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Algorithm** & **Strategy** & \multicolumn{4}{c}{**Hours-Set**} \\
**6** & **12** & **18** & **24** \\ \hline \multirow{2}{*}{IF} & Flexible Start & 3.91\% & 4.50\% & 5.20\% & 6.05\% \\  & Pause \& Resume & 3.23\% & 5.09\% & 5.71\% & 7.01\% \\ \hline \multirow{2}{*}{SVM} & Flexible Start & 3.07\% & 5.17\% & 6.29\% & 7.51\% \\  & Pause \& Resume & 3.81\% & 5.44\% & 5.59\% & 6.74\% \\ \hline \multirow{2}{*}{HF-SCA} & Flexible Start & 2.27\% & 2.49\% & 2.63\% & 2.80\% \\  & Pause \& Resume & 1.48\% & 3.20\% & 4.88\% & 4.99\% \\ \hline \multirow{2}{*}{AE} & Flexible Start & 3.97\% & 4.90\% & 5.39\% & 6.56\% \\  & Pause \& Resume & 3.20\% & 5.31\% & 6.04\% & 7.31\% \\ \hline \hline \end{tabular}
\end{table}
Table 3: Emissions percentage reduction across all regions.  
et al. [9] report on algorithms achieving around 26% of carbon savings (particularly the Dense experiments). However, if we consider experiments with similar duration (19 h for ViT tiny/small), carbon savings return a little more comparable, falling to approximately 5.5%. Nevertheless, percentages from the state-of-the-art double what we have observed in our experiments. This may be due to the different variability range of MOER, as mentioned at the beginning of this section. The regions we consider in this work are generally cleaner; hence, the effectiveness of any carbon-aware strategy is expected to be lower. However, it can be stated that Flexible Start provides robust carbon savings to longer workloads, even for cleaner regions.  
For shorter workloads, we do not have directly comparable times: in our experiments, SVM, AE, and IF (in order of workload length) last around 2-4 h, while [PERSON] et al. [9] report on Bert finetune (6 h) and three DenseNets (20-25 min). Energy consumption is also not comparable (see Tables 1 and 3). Flexible Start provides a 14.5% carbon savings to the BERT finetune while achieving 26% for DenseNets as already outlined. In our experiments, we observe the same trend: the shorter the workload, the higher the savings provided by Flexible Start. Specifically, we have: IF, lasting 4:15 and saving 4.89%; AE, lasting 3:30 and saving 5.71%; SVM, lasting 2:30 and saving 6.67%. By the way, results are much less comparable in the case of short workloads. We can deduce that the effectiveness of Flexible Start highly depends on the greenness of the region.