I'm not clear what you mean by "represents". The logger records every minute, but you only want the data from every fifth or fifteenth minute? Or do you want a running average of those measurements based on those intervals?

The former probably requires a helper column which should be fairly easy. 15 minutes in Excel is equal to 15/(24*60). You could set up a helper to only identify those rows where the mod() of the time with that ratio is zero or something like that.

For the latter, you can group and average with a pivot, but only by minutes, hours, days, etc. To do so by 5 minutes or 15 minutes would require a helper column which should be even easier.

Making it robust to manage the intervals to satisfy your regulations is mere window dressing. Should be pretty easy.