Perhaps you should try some spelling variations:
"improving thermal performance metrics." » "improving thermal performance measures.", "improving external performance metrics.", "improving animal performance metrics.", "improving erm performance metrics."
"improving rural performance reviews." » "improving rural performance review.", "improving rural performance reports.", "improving rural performance risks.", "improving euract performance reviews.", "improving larval performance reviews.", "improving pupil performance reviews."

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 metrics.") or ("improving rural performance reviews."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("improving thermal performance metrics.") OR ("improving rural performance reviews."))*.
• Removing quotes may allow a broader search: (( improving thermal performance metrics. ) or ( improving rural performance reviews. ))*.