Have you heard your air conditioner repairman use terms you didn’t understand? Are you a new home energy auditor or HERS rater trying to figure out how heating and cooling systems work? There’s a lot of jargon in the world of HVAC (including those initials), and I’ll demystify some of it for you here. There’s no way I can get it all here, so I’ll hit what I think are the most important. If I miss one you think should be included, let me know in the comments below.