Test Reference Year (TRY)

Test Reference Year (TRY) is historical digital data set DSI-9706, archived at the National Centers for Environmental Information (NCEI; formerly National Climatic Data Center, NCDC). Following an ASHRAE-approved procedure the TRY consists of hourly weather data values for a selected reference year for 60 selected U.S. cities. The period of record examined is 1948-1975 for 59 of the stations; Portland, OR, the 60th station, has a period of record of 1949-1975. The principle of selection is to eliminate years in the period of record containing months with extremely high or low mean temperatures until only one year remains. Extreme months are arranged in order of importance for energy comparisons. Hot Julys and cold Januarys are assumed to be the most important. All months are ranked by alternating between the warm half (May to October) and the cold half (November to April) of the year, with the months closest to late July or late January given priority. Variables included: Dry bulb temperature, wet bulb temperature, dew point temperature, wind speed and direction, station pressure, present weather and obscuring phenomena, total sky cover and layered cloud data. A placeholder for solar radiation is included but no measured or calculated solar data are included.