daylight factor


Definition of daylight factor

: the ratio of the illumination from windows at any point indoors to that out in the open, the test surface being horizontal in each case

called also window-efficiency ratio

Love words?

You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.

Start your free trial today and get unlimited access to America's largest dictionary, with:

  • More than 250,000 words that aren't in our free dictionary
  • Expanded definitions, etymologies, and usage notes
  • Advanced search features
  • Ad free!

First Known Use of daylight factor

1915, in the meaning defined above

Keep scrolling for more

Learn More about daylight factor

Time Traveler for daylight factor

Time Traveler

The first known use of daylight factor was in 1915

See more words from the same year

Statistics for daylight factor

Cite this Entry

“Daylight factor.” Dictionary, Merriam-Webster, Accessed 5 Dec. 2020.

Comments on daylight factor

What made you want to look up daylight factor? Please tell us where you read or heard it (including the quote, if possible).


Test Your Vocabulary

Musical Words Quiz

  • gramophone
  • Which word describes a musical performance marked by the absence of instrumental accompaniment?
Spell It

Can you spell these 10 commonly misspelled words?


Test Your Knowledge - and learn some interesting things along the way.

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!