A CD holds under 800mb of WAV, even 24/96 WAV. FLAC at its highest compression ratio is roughly 35% to 40% of that. That assumes the CD is full. The only way you can get to over 1gb is if:
1. The album spans more than 1 CD
2. You didn't apply highest FLAC compression on 24/96 studio master FLAC
3. You have too many other files in there, like whatever ripper you used made multiple copies of the album cover (one for each song as opposed to linking all to a single JPEG) in high res JPEG, or the whole album cover sleeve was scanned into the file (as would be found in albums from torrents).