## 9111 The Temperature Bin Method

The Temperature Bin Method requires that instantaneous energy calculations be performed at many different outdoor temperature conditions, with the results multiplied by the number of hours expected at each temperature condition. The "bins" referred to represent the number of hours associated with groups of temperatures, and are compiled in 5°F increments. The hour tabulations are available in annual, monthly and sometimes 8-hour shift totals. All hourly occurrences in a bin are assumed to take place at the bin "center-temperature." For example, it is assumed that 42°F quantitatively represents the 40-44°F bin.

The basic methodology of this method requires calculating the unique heat loss at each bin by multiplying the BLC by the difference between the indoor temperature assumed and the center-temperature for each respective bin. This result is in turn multiplied by the number of hours in the bin. The products of all the

More accurate energy predictions will result by omitting calculations for bins whose center temperature exceeds the assumed balance temperature. For example, no calculation should be performed for the 50-54°F bin, if the predicted balance temperature is 50°F. The center temperature of 47°F for the 45-49°F bin indicates that a 3°F temperature difference is appropriate for that bin (50- 47°F).

A complete description of the bin method can be found in the ASHRAE Handbook of Fundamentals.

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