Another often-debated topic related to the daylighting of nineteenth century skyscrapers is the role of the bay window. The bay window, when added to the exterior of an office building served only one purpose: to increase the amount of floor area for which an owner could charge rent, by projecting each floor of the building past the lot line of one’s property. Literally this detail usurped the air rights of the public’s sidewalk. Nobody had stated this fact more clearly than had Owen Aldis, who in a letter to Peter Brooks describing Burnham and Root’s final design of the Monadnock Block, relayed, “Numerous bays for extra floor space.” Even Frank Lloyd Wright referred to the bay windows in Louis Sullivan’s Stock Exchange as free real estate, “Calculate the floor space stolen, by ordinance, from the street and see ‘why’ they were there!” Some historians have argued that the role of the bay window was to increase the amount of daylight and ventilation. I want you to stop and think about this issue for a moment. If you are not increasing the size of the opening in the wall (the bay window is not making the opening larger, it is simply hanging a glass box over this opening), how is more light able to enter through the opening? If the opening is the same size, how could more light be admitted into the interior with the addition of a bay window? While the slight angle of the projecting bay may have marginally increased the amount of ventilation on days when the wind was blowing parallel to the face of any particular wall, just the opposite resulted with regards to daylighting.
By projecting the ceiling of the bay window beyond the plane of the building’s exterior, the depth of the penetration of daylight into the interior was correspondingly reduced, not increased. Right? (Remember the 24-5’ rule of the depth of daylight penetration from the window head at the ceiling. If you push out the window head 24,” the maximum penetration of the daylight correspondingly moves 24” closer to the exterior.)
One other architectural issue related to the need to maximize the daylighting in the design of an early skyscraper was the potential solar heat gain that could result from so much glass in the exterior walls of these buildings, especially on the south and west faces. If our only knowledge of these buildings came from the first histories of the modern European International Style, that attempted to make a direct connection between the early skyscrapers of the Chicago School and the all-glass buildings designed in Europe during the 1920s, we would have to believe that either the occupants of the early Chicago skyscrapers baked during the summers, or the amount of natural ventilation provided by the operable windows provided sufficient air movement to flush the sun’s heat on a regular basis.
Fortunately, there are different photographs of Chicago’s early skyscrapers than the ones chosen by the authors of these early histories. The last thing one would want to put on an International Style glass box would be an awning, and yet, that is precisely the solution nineteenth century American architects employed to respond to the solar heat gain.
For the longest time, I had assumed that the awnings on the early skyscrapers that I saw in photographs had been placed there by unsophisticated tenants, who simply had no appreciation for the building’s aesthetics. Then one day I came across a series of renderings by Louis Sullivan of skyscrapers he had designed, but were never built, and to my astonishment, he had drawn on each building a number of awnings! I had stumbled upon a well-kept secret: the early historians of the International Style had only used photographs of the Chicago School buildings in the winter when their awnings had been removed in order to prevent the snow and ice from damaging them…
There are a number of other issues that pertain to commodity, such as improvements in elevators (see Lee Gray’s excellent book: A History of the Passenger Elevator) and plumbing, forced ventilation systems, the telephone, and steam-powered construction equipment, that each, obviously, played their parts in the evolution of the skyscraper. I have had to limit my research somehow and, quite simply, did not have the time or the space to include studies of these important issues in this work. There is, however, one mechanical issue that did play an important role that I will include in the early chapters. The fact was that the first skyscrapers grew at a pace faster than that of contemporary firefighting techniques and equipment. For many years, buildings were built that were higher than the limit of a fire department’s ability to throw water upon a fire. The are countless reports of fires starting in the top floors of buildings which the firefighters either could not reach with the water pressure available or failures in the equipment intended to assist them in getting up to the height necessary to fight such a fire. The firemen simply had to wait until the fire reached a floor low enough for their water to reach. I have already documented in Volume One this phenomenon that occurred immediately after the 1871 fire that had forced owners to stop building such tall buildings, if even for a just a short period.
(If you have any questions or suggestions, please feel free to eMail me at: thearchitectureprofessor@gmail.com)
The Architecture Professor 