Perhaps you should try some spelling variations:
"Improving thermal performance contract." » "Improving thermal performance contracts."
"improving thermal performance reviews." » "improving thermal performance review.", "improving thermal performance reports.", "improving thermal performance risks.", "improving external performance reviews.", "improving animal performance reviews.", "improving erm 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 contract.") or ("improving thermal performance reviews."))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: (("Improving thermal performance contract.") OR ("improving thermal performance reviews."))*.
• Removing quotes may allow a broader search: (( Improving thermal performance contract. ) or ( improving thermal performance reviews. ))*.