Columbia University Libraries Digital Collections: The Real Estate Record

Real estate record and builders' guide: [v. 98, no. 2543: Articles]: December 9, 1916

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REAL ESTATE AND NEW YORK, DECEMBER 9, 1916 RELATION OF HEIGHT AND AREA TO SUNSHINE Statement by Herbert S. Swan and George W. Tuttie, of the Staff of the Committee on City Plan BUILDING requirements in Manhat¬ tan have in the past been so lax that it is safe to say that a preponderat¬ ing majority of rooms in the existing shops, factories, offices and apartments receive absolutely no direct sunshine on the shortest day in the year. The height and area regulations now being considered will have the tendency of remedying this condition. Bv limit¬ ing the height of buildings with refer¬ ence to the street width and by requiring all windows to open out on either streets or open spaces of a prescribed size the zone plan will provide a larger _ supply of direct sunshine not only in the interior of all new residence and business build¬ ings, but also in the streets. The following paper shows the relation of these provisions to the duration and quantity of direct sunshine obtained un¬ der different conditions at New York City (40° North Latitude) as on Decem¬ ber 21. At noon, on the shortest day of the year, the shadows of different sky¬ scrapers envelope large areas. The Adams Express Building, which is 424 feet high, casts a shadow 875 feet in length; the Equitable Building, which is 493 feet high, one 1,018 feet in length; the Singer Tower, which is 546 feet high, one 1,127 feet in length; and the Wool- worth Tower, which is 791 feet high, one 1,635 feet in length. The effect of skyscrapers casting shad¬ ows from a sixth to a third of a mile in length on surrounding property is well illustrated in the case of the Equit¬ able Building. Its shadow, which at noon on December 21 is about one-fifth of a mile in length, completely envelops an area of 7.59 acres. The ground area of the Equitable Building is only 1.14 acres'. The shadow cuts off all sunshine from the Broadway facade of the United States Realty Building, which is twenty- one stories high. The New York Title & Mortgage Company Building, four¬ teen stories high, and the Washing¬ ton Life Insurance Building, nineteen stories high, are both completely shaded. The south side of the Singer Tower is shaded to a height of twenty- seven stories. Tlie nearest part of the City Investing Building 400 feet away is in shadow for twenty-four of its twenty- six stories. Even part of the New York Telephone Building north of Cortlandt street is shadowed by the Equitable Building. For almost a fiftli of a mile this giant skyscraper casts its shadow. The area cut off by it from all noonday sunlight extends to within 100 feet of Fulton street. Cedar street, the street immediately north of the Equitable Building, has an average width of 34 feet between Broad¬ way and Nassau street. The height of the Equitable Building is 14J/2 times the width of this street. On a north and south street of this width in New York, uniformly improved on both sides with buildin.gs having a height equal to that of the Equitable Building, only 9.31 per cent, of the windows would receive any direct sunshine at noon on the shortest day in the year. On north and south streets only the windows nearest the top for a distance equal to .1.35 times the width of the street would receive direct sunshine at noon on December 21 at New York (40° North Latitude). The windows in tlie first thirty-four stories nearest the ground would receive abso¬ lutely no direct sunlight, Direct sun¬ shine would only enter those windows in the four stories nearest the top. Not a single window within 447 feet of the street level would receive a ray of direct sunshine. The Equitable Building is, of course, an cxtren-.e case. But even in much lower buildings a considerable number of the windows on north and south streets receive absolutely no direct sunshine at the winter solstice. Up to a height equal to 1.35 times the width of such a street posite side of the street, 28 per cent, of the sunshine period on a north and south street is cut off by the thickness of the wall in which the window is set. Where the opposite buildin.gs rise to a height above the window equal to .2 times the width of the street, 35 per cent, of the sunshine period is cut off; where it rises to a height .4 times the width of the street, 44 per cent, is cut off; .6 times, 54 per cent.; .8 times, 65 per cent.; 1.0 times, 77 per cent.; and 1.35 times 100 per cent. Time af which sun is eclipsed by given- height of bi/llding in terms of street widtf) Streetmcif/i.-%^ -^^ .Oi Oft Ns ^ *0 '^ . '..... Hours before or offer noon. VOLUME, or SUIV8mN£ ADM/nZD BY W/NDOW. Calculated for gi\ten room with window open¬ ing on north and south street. Latitude 40'N. all the windows (assuming they fulfill the standard requirements described below) receive some sunshine. If the street, liowever, is improved witli buildings one and one half times the street width in height only 90 per cent, of the windows obtain direct sunshine. If the height be increased to two times the street width the proportion receiving direct sunshine is reduced to 67.5 per cent. The number of windows receiving direct sunshine on north and south streets with buildings of different heights is as follows: Two and one-half times, 54 per cent.; three times, 45 per cent.; four times, 34 per cent.; five times, 27 per cent.; and six times, 22.5 per cent. In this connection it must be remem¬ bered that all windows receiving "sunlight do not obtain the same amount. Even though there be no buildings on the op- This is for a wall 14 inches thick. For a thicker wall the percentage would in each case be more; for a thinner wall less. A window in a north and south street situated in a position where the height of the Iniildings opposite it is .2 times the width of the street above its center level receives direct sunlight for a period the length of which is only 72 per cent, of that received by an unobstructed win¬ dow; where the Iieight of the buildings opposite is .4 times, SO per cent.; .6 times, ZZ per cent.; .8 times, 21 per cent.; and 1.0 times, 12 per cent. The duration of the sunshine period of tlie facade and in the rooms on a north and south street at the winter sol¬ stice is shown in the following table for different points below the top of the op¬ posite buildings: