Window Awnings
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PRESERVATION Tech Notes NATIONAL PARK SERVICE u.s. DEPARTMENT OF THE INTERIOR WASHINGTON, D.C. WINDOWS NUMBER 7 Window Awnings FLORIDA STATE CAPITOL Tallahassee, Florida Laura A. Muckenfuss Center for Architectural Conservation Georgia Institute of Technology, and The old Florida State Capitol, constructed reducing glare; can provide rain protec Charles E. Fisher in the I 840s and greatly enlarged over the tion for windows opened for ventilation; Preservation Assistance Division years, has recently been rehabilitated for and can bring a bright, cheerful addition National Park Service use as museum space and government to a building. Given the high visibility of offices. The neo-classical revival building such a window treatment, research should has been returned to its 1902 appearance be undertaken to ensure that awnings and is individually listed in the National previously had been used on the building; Register of Historic Places. care should be taken to match the size, Photographs in the Florida Photo design, color, and basic appearance of the graphic Archives show that as early as historic awnings where possible. the 1890s decorative awnings had been The Florida State Capitol project is a installed, replacing shutters as sun good example where replication of the screens. Wide-striped red and white oper awning treatment was undertaken pri able awnings can be seen in postcards as marily because of the cost savings early as 1902. By World War II, air con realized through reduced energy usage. ditioning units had been added to the build The architect and the mechanical ing, and the awnings had been removed. engineer for the work at the Capitol were When rehabilitation plans were concerned from the outset about the high drawn up for the building, the initial cooling load created by the large glass intention was not to duplicate the area on the building's facade. The cooling awnings. Energy studies, however, load required to handle the solar gain showed that significant cost savings could from the 138 windows that measured 4' be Ilchieved by installing the awnings, by 10' each was calculated at 55 tons . and today the building stands with this There were also significant air infiltration highly colorful feature added. problems due to a lack of weatherstrip ping and window maintenance. It was Rehabilitation Design Problem estimated that mechanical equipment with a capacity of 102 tons refrigeration The effective use of awnings to reduce (which includes the 55 ton load for just solar heat gain can be found on numerous the windows) would be needed to cool the historic buildings during the late 19th and 46,501 square feet of building area, and early 20th centuries, and it still is a concern was expressed that the air treatment with practical applications in velocity from such a system might have certain climates. In hot climates awnings created drafty conditions in the smaller can eliminate the need to alter or replace offices within the building. An engineer Installing historically appropriate existing historic windows for reasons of ing study of two offices on the west awnings can effectively reduce solar improved energy performance while also facade of the building showed that 72% of heat gain. the required cooling load in a typical first Rehabilitation Design Solution Fabrication And Installation floor office and 56% of the load in a typical second floor office was due to It was determined that installation of the A decision had to be made on the type of exposed glass surface. With the windows awnings would appreciably reduce heat material to be used for the awnings. contributing to 54% of the overall air gain and cut energy consumption during Canvas awnings had been used on the conditioning load, some measures were Florida's long hot weather season and building from the 1890s through the necessary to reduce the heat gain from the also enable the Capitol project to remain 1930, but records showed that the canvas windows. within its $7 million budget. This was lasted only three to four years in the Some of the sash were in good possible, despite the purchase cost of the Florida climate. A modern material of condition, and it would have been awnings, in part because of the cost acrylic fibers with an eight-year life possible to add tinted heat-absorbing savings resulting from the ability to expectancy was selected instead to reduce insulating glass by rabbeting out the reduce the size of the HV AC system. The the long-term maintenance needs. A local existing sash frames. Alternatively, tinted size, shape and installation angle of the marine products company was located glass could have been installed both in original awnings as shown in the archival that sold the acrylic fabric . existing sash that were repairable as well records were duplicated in the new work. The awnings were fabricated to the as in the numerous sash replacement units Since the primary facades of the architect's design of 4' wide by 4' deep needed. There were concerns, however, Capitol faced east and west, awnings with a height of 8' -I" and a 9 W' scalloped over such visual changes to the historic were needed on the two main floors on all valence (see figure 2). The 100% acrylic appearance of the building; finally , cost but the north side (see figure 1). Solar fabric has vertical stripes four inches considerations were an important factor heat gain, which originally would have apart. Regrettably the production of the weighing against the use of insulating and consumed 54% of the required cooling acrylic weave did not allow for pure color new tinted glass. Rising energy costs and load, was now estimated to be 31.5% of separation, and as a result the striping is the savings from the reduction in the size the equipment load, and allowed a in reality red and a very light pink; still of the HV AC system made the reinstalla downsizing of the HV AC system by 2? the impression of red and white is tion of the awnings both a practical and tons. In typical first floor offices, the maintained. economical alternative. exposed glass surface would now only account for 46% of the required cooling Figure 2. Early photographs were used in determining the appropriate design and size of Figure 1. Large awnings were specified for aU load down from 72%. On the second the new awnings shown in the photograph. but the north elevation in order to reduce floor, there was a similar change from Drawing: Courtesy, Shepard Associates, solar gain. Drawing: Courtesy, Shepard Asso 56% down to 30%. Architects and Planners, Inc.; Photo: Cour ciates, Architects and Planners, Inc. tesy, Florida Bureau of Historic Preservation. ~ ARC H. SHEET ~ MET AL CORNICE ro lell Itdl --19 TOP OF MASONRY ELEVA TION 255.90 - = .----,.1 .---- .---- ;r cry ':" N t==. .==. ~ TOP OF -===- UNDERLAYMENT ELEVATION 234.67 (0 :::: ~ -r in ~ TOP OF UNO ERLAYMENT D D D I ELEVATION 219.82 .---- .---- .---- ......Co ~ 'fl 0 ~ .====. ..== .==. = T OPOF BRICK ELEVATION 205.75 , J NEW AWNINGS TYPICAL ON FIRST AND SECOND FLOOR WINDOWS ON EAST, WEST & SOUTH ELEVATIONS ~rL 4'-0 )\L )\l 2 The awning fabric can be readily tion and as a result of the downsizing of easily retract the awnings. The awnings removed from the frame for replacement the HVAC system. now are performing admirably and this and cleaning. Standard galvanized steel highly distinctive historic feature has awning frames designed to draw vertical Project Evaluation generated considerable local interest (see ly against the window frame were used. figure 4). Since the windows in the Capitol were The Florida State Capitol project has shown that awnings can be an effective sealed shut for weatherization purposes Figure 4. While the awnings were installed in and to keep a more constant load demand means of reducing heat gain. Commonly order to save on energy costs, the restoration on the HV AC system, the pivoting points used in the past as a passive design of this highly decorative and colorful feature on the standard frames were easily made feature to keep a building cool, awnings enhances the historic appearance of the rigid, preventing retraction of the have received renewed interest in the building. Photo: Courtesy, Florida Bureau of Historic Preservation. awnings. 1980s because of their energy-conserving The decision to fix the awnings in a qualities. fully opened position did have some cost The use of the acrylic fabric as a trade-offs, since solar, gain through the substitute material for the original cotton windows during the short cold weather duck canvas avoided the problem of season would have been desirable. There shrinking that canvas exhibits. Moreover, also would be an advantage to be able to acrylic is not affected as badly by adjust the awnings to allow natural light mildew. It is also anticipated that the when the rays of the sun were not directly reinstallation of the awning with their shining on the windows. In addition, the protective overhang will provide some viewing area through the window would additional cost savings through extended be permanently reduced in the upper life for the windows. portions of the windows. Operable The decision to make the frames awnings could have been provided by rigid to prevent retraction of the awnings having the mechanical opening hardware on the Florida State Capitol did prove to extend through to the inside. This more be unwise, since seasonal high winds, costly feature was not selected for use in exacerbated by large adjacent new con the Capitol. struction, caused greater damage than had The hardware for the awnings, been anticipated. To correct this con including the anchors and attaching dition, the windows, which had been devices, were primarily galvanized or screwed shut and sealed, were easily zinc plated steel.