Response from the organisers:
That’s correct—the 20% and 45% values do not refer to the number of “rows” or chunks. Instead, they refer to the proportion of time series allocated to the private, public, and secret sets during dataset preparation, as described here: AIcrowd | Brick by Brick 2024 | Challenges
Specifically, during the preparation stage:
All data from the three buildings are combined into a single dataset and then segmented into distinct sets for training, leaderboard testing, and secret competition testing.
In this step, approximately 20%, 45%, and 35% of the time series are assigned to the private, public, and secret sets, respectively. However, note that the length of each time series can vary. Later, the dataset undergoes further processing which yield the “rows” and “chuncks” available to the participants:
Time Series Chunking: The dataset is further divided into shorter segments or chunks with durations ranging from 2 to 8 weeks.
I hope this clarifies your concern.