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 review." » "improving export performance risk.", "improving export performance evidence.", "improving exposure performance review.", "improving eap performance review.", "improving eco performance review."

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 review."))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"improving thermal performance series.\") OR (\"improving export performance review.\"))*".
• Removing quotes may allow a broader search: (( improving thermal performance series. ) OR ( improving export performance review. ))*.