Perhaps you should try some spelling variations:
"improving thermal performance series." » "improving thermal performance studies.", "improving thermal performance size.", "improving external performance series.", "improving animal performance series.", "improving erm performance series."
"improving export performance evidence." » "improving exposure performance evidence.", "improving eap performance evidence.", "improving eco performance evidence."

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: (("improving thermal performance series.") or ("improving export performance evidence."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance series.") OR ("improving export performance evidence.")).
• Removing quotes may allow a broader search: (( improving thermal performance series. ) or ( improving export performance evidence. )).
• Adding a wildcard symbol may retrieve word variants: (("improving thermal performance series.") or ("improving export performance evidence."))*.