. . . this pattern helps to complete the work of Light on Two Sides of Every Room, by going even further to reduce glare; and it helps to shape the Frames as Thickened Edges.
Problem:
Windows with a sharp edge where the frame meets the wall create harsh, blinding glare, and make the rooms they serve uncomfortable.
Background & Research: Not Included on the site—Go read the book!
Solution:
Make the window frame a deep, splayed edge: about a foot wide and splayed at about 50 to 60 degrees to the plane of the window, so that the gentle gradient of daylight gives a smooth transition between the light of the window and the dark of the inner wall.
Usage:
Build the depth of the frame so that it is continuous with the structure of the walls—Frames as Thickened Edges; if the wall is thin, make up the necessary depth for the reveal on the inside face of the wall, with bookshelves, closets or other Thick Walls; embellish the edge of the window even further, to make light even softer, with lace work, tracery, and climbing plants—Filtered Light, Half-Inch Trim, Climbing Plants . . .
pg. 1053