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12 A History of School Design and its Indoor Environmental Standards, 1900 to Today In one guidebook published at the time, authors noted another major reason for building schools only one story high, saying, “[m]ulti-story buildings are more diffi cult to evacuate than single-story buildings” (National Council on Schoolhouse Construction, 1964, p. 96). 4.1 Evaluation and standards Figure 8. Crow Island School, Perkins & Will Architects, courtesy of Tanner and Lackney, 2005. 4.1.1 Ventilation, Heating and Air Quality In a report written by the chief of the School Housing Section of the U.S. Offi ce of Education (later known as the Department of Education), Ray Hamon detailed the needs for research in his fi eld in a 1948 article, noting that often the research did not match current practice, saying, “[t]here has probably been more research on heating and ventilating than on any other feature of the school plant. Although there has been rather general agreement on desirable conditions, many codes are still based on false principles” (Hamon, 1948). In a similar article in 1951, Gray notes some specifi c areas of research that are still in question today in regards to heating and ventilation: In the fi eld of heating and ventilation the following are some of the unanswered questions: (a) Is windowgravity-ventilation feasible and satisfactory in all climates and seasons? (b) If mechanical systems of heating and ventilating are used, what are the optimum volumes of air per pupil, numbers of air changes, and proportions of fresh and recirculated air? (c) What are the optimum temperature and humidity conditions for health and alertness in the different school activities(Gray, 1951)? At this point in the evolution of ventilation standards for classrooms, required cubic feet per minute (cfm) per person had been lowered to 10 (from 30 cfm in the 1920s). This was a result of research conducted for the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) then known as the American Society of Heating and Ventilating Engineers (ASHVE), by Yaglou and his colleagues in the late 1930s which measured olfactory sensation in rooms, where they determined that air was not perceptibly bad until ventilation rates were lower than 10 cfm (Janssen, 1999). This research was National Clearinghouse for Educational Facilities a program of the National Institute of Building Sciences 1090 Vermont Avenue, N.W., Suite 700, Washington, DC 20005-4950 202-289-7800 www.ncef.org © 2012, National Institute of Building Sciences
A History of School Design and its Indoor Environmental Standards, 1900 to Today the support for codes using the 10 cfm threshold starting in the 1930s and continuing through the fi rst version of ASHRAE 62 - Standard for Natural and Mechanical Ventilation in 1973. In the Architectural Forum issue, thermal comfort is introduced as a particularly diffi cult area of school design, with the author noting, “there are few types of work in which the static analysis that is the basis of most heating design comes into such open and obvious confl ict with the everyday realities as in the school classroom” (Luce, 1949, p. 144). He goes on to remind the reader, This is so in the fi rst place because the use of such rooms, and consequently their heating, is on an intermittent rather than a constant or nearly constant basis. Schoolrooms are normally used only during the daytime, and during the middle daylight hours at that.... Secondly, schoolrooms are in use during the time of day when solar heat gain is at a peak.... Since almost all classrooms today have a great deal of class- from National Clearinghouse for Educational Facilities a program of the National Institute of Building Sciences 1090 Vermont Avenue, N.W., Suite 700, Washington, DC 20005-4950 202-289-7800 www.ncef.org © 2012, National Institute of Building Sciences 13 20 per cent of the fl oor area upwards- the solar heat gain is tremendous.... Finally, classroom heating is complicated by density of occupancy (ibid). This heat fl ux is carefully depicted in a lovely graphic reproduced in Figure 9. The author then goes on to caution the reader about the large expanse of windows, noting that this can cause signifi cant thermal discomfort in occupants, especially those sitting near a window. In another charming illustration that can be seen in Figure 10, the author explains that the cold surfaces of windows can be offset by heating panels placed below the windows and on the ceiling above windows, to help combat this problem. In general, as can be seen from the writings of this period, thermal comfort was becoming an increasingly technical and complex fi eld, and expertise was growing ever more specifi c as mechanical engineers took on greater responsibilities in providing narrow temperature bands and specifi c humidity levels for classrooms. This Figure 9. A conceptual graph of the heat fl ux in a typical classroom, from Architectural Forum, 1949.
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