223. DEEP REVEALS

<h2>223...DEEP REVEALS</h2>

<h6>. . . this pattern helps to complete the work of <a href="http://www.patternlanguage.com/apl/apl159/apl159.htm">LIGHT ON TWO SIDES OF EVERY ROOM (159)</a>, by going even further to reduce glare; and it helps to shape the <a href="http://www.patternlanguage.com/apl/apl225/apl225.htm">FRAMES AS THICKENED EDGES (225)</a>.

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<h3>Windows with a sharp edge where the frame meets the wall create harsh, blinding glare, and make the rooms they serve uncomfortable.</h3>

<h3>Therefore:</h3>

<h3>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.</h3>

<p>They have the same effect as the bright headlights of an oncoming car: the glare prevents you from seeing anything else on the road because your eye cannot simultaneously adapt to the bright headlights and to the darkness of the roadway. just so, a window is always much brighter than an interior wall; and the walls tend to be darkest next to the window's edge. The difference in brightness between the bright window and the dark wall around it also causes glare.

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<div align="center"><em>Glare . . . and no glare.</em></div>

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To solve this problem, the edge of the window must be splayed, by making a reveal between the window and the wall. The splayed reveal then creates a transition area - a zone of intermediate brightness - between the brightness of, the window and the darkness of the wall. If the reveal is deep enough and the angle just right, the glare will vanish altogether.</h6>

<p>But the reveal must be quite deep, and the angle of the splay quite marked. In empirical studies of glare, Hopkinson and Petherbridge have found: (1) that the larger the reveal is, the less glare there is; (2) the reveal functions best, when its brightness is just halfway between the brightness of the window and the brightness of the wall. ("Discomfort Glare and the Lighting of Buildings," <em>Transactions of the Illuminating Engineering Society,</em> Vol. XV, No. 2, 1950, pp. 58-59.)</p>

<p>Our own experiments show that this happens most nearly, when the reveal lies at between 50 and 60 degrees to the plane of the window; though, of course, the angle will vary with local conditions. And, to satisfy the need for a "large" reveal, we have found that the reveal itself must be a good 10 to 12 inches wide.</p>

<div align="center"><a id="7c266035-ae1e-449d-aebf-7ec4d1d07730" class="brain-processing" href="http://www.patternlanguage.com/apl/threedots.jpg">http://www.patternlanguage.com/apl/threedots.jpg</a></div>

<h6>Build the depth of the frame so that it is continuous with the structure of the walls - <a href="http://www.patternlanguage.com/apl/apl225/apl225.htm">FRAMES AS THICKENED EDGES (225)</a>; 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 <a href="http://www.patternlanguage.com/apl/apl197/apl197.htm">THICK WALLS (197)</a>; embellish the edge of the window even further, to make light even softer, with lace work, tracery, and climbing plants - <a href="http://www.patternlanguage.com/apl/apl238/apl238.htm">FILTERED LIGHT (238)</a>, <a href="http://www.patternlanguage.com/apl/apl240/apl240.htm">HALF-INCH TRIM (240)</a>, <a href="http://www.patternlanguage.com/apl/apl246/apl246.htm">CLIMBING PLANTS (246)</a>. . . .</h6>

<h4><em>A Pattern Language</em> is published by Oxford University Press, Copyright Christopher Alexander, 1977.</h4>

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223. DEEP REVEALS

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