Perhaps you should try some spelling variations:
"improving thermal performance review." » "improving thermal performance risk.", "improving thermal performance evidence.", "improving maternal performance review.", "improving human performance review.", "improving mental performance review."
"improving rural performance contracts." » "improving pupil performance contracts.", "improving overall performance contracts.", "improving fiscal performance contracts.", "improving urban performance contracts.", "improving social performance contracts."

Try widening your search to All Fields.

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 review.") or ("improving rural performance contracts."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance review.") OR ("improving rural performance contracts.")).
• Removing quotes may allow a broader search: (( improving thermal performance review. ) or ( improving rural performance contracts. )).
• Adding a wildcard symbol may retrieve word variants: (("improving thermal performance review.") or ("improving rural performance contracts."))*.