alcove vs machine room

alcove

noun
  • A small recessed area set off from a larger room. 

  • A shady retreat. 

machine room

noun
  • A limited-access room in a larger building dedicated to HVAC equipment and other machinery. 

  • A dedicated room for computers and related data processing equipment, often having a raised floor, abundant and dedicated air conditioning, and specialized power supply and fire suppression systems. 

How often have the words alcove and machine room occurred in a corpus of books? (source: Google Ngram Viewer )