Perhaps you should try some spelling variations:
"improving thermal performance risk." » "improving maternal performance risk.", "improving human performance risk.", "improving mental performance risk.", "improving thermal performance size.", "improving thermal performance based.", "improving thermal performance _."
"improving rural performance targets." » "improving pupil performance targets.", "improving overall performance targets.", "improving fiscal performance targets.", "improving urban performance targets.", "improving social performance targets."

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