Answer:
technical expertise
Explanation:
technical expertise refers to the high level of knowledge acquired (usually through work experience) about some type of technology or technical work. For example, a mechanic that has repaired cars for more than 30 years would be considered to have technical expertise.
In this case, Jasper's 20 year long experience means that he knows a lot about air conditioners and heating, and that he might be able to train others to pass that knowledge. In Europe, seasoned employees, are very valuable because they takes apprentices and teach them what they learned during their long careers.