ASHRAE-Standard-55 - Page 008

Extracted Content

5.2 Method for Determining Occupant Characteristics 5.2.1 Metabolic Rate 5.2.1.1 Rate for Each Representative Occupant. For each representative occupant, determine the metabolic rate associated with the occupant’s activities. Averaged metabolic rates shall not be used to represent multiple occupants whose metabolic rates differ by more than 0.1 met. Informative Note: For example, in an office setting, when comparing an occupant who is seated and read ing at 1.0 met with an occupant that is typing at 1.1 met, they can be grouped as a single representative occupant. If the same seated occupant is compared to an occupant who is seated and filing at 1.2 met, each shall be considered separately when determining the conditions required for thermal comfort. 5.2.1.2 Rate Determination. Use one or a combination of the following methods to determine metabolic rate:

a. Metabolic rates for typical occupant activity types given in Table 5-1 shall be used to describe the repre sentative occupant. Where a range is given, select a single value within that range based on characteristics of the activity. If a proposed occupant activity type is not listed in Table 5-1, the most similar activity type based on characteristics of the activity shall be used. b. Interpolate between or extrapolate from the values given in Table 5-1. c. Use estimation and/or measurement methods described in ASHRAE Handbook—Fundamentals [ 1], Chap ter 9. d. Use other approved engineering or physiological methods.

5.2.1.3 Time-Weighted Averaging. Use a time-weighted average metabolic rate for individuals with activities that vary. Such averaging shall not be applied where an activity persists for more than one hour. In that case, two distinct metabolic rates shall be used. Informative Note: For example, a person who spends 30 minutes out of each hour “lifting/packing,” 15

minutes “filing, standing,” and 15 minutes “walking about” has an average metabolic rate of 0.50 × 2.1 + 0.25 × 1.4 + 0.25 × 1.7 = 1.8 met. However, a person who is engaged in “lifting/packing” for more than one hour and then “filing, standing” for more than one hour shall be treated as having two distinct metabolic rates per Section 5.2.1.1. 5.2.1.4 High Metabolic Rates. This standard does not apply to occupants whose time-averaged metabolic rate exceeds 4.0 met.

5.2.2 Clothing Insulation 5.2.2.1 Insulation for Each Representative Occupant 5.2.2.1.1 For each representative occupant, determine the clothing insulation Icl in clo. 5.2.2.1.2 Averaged clothing insulation Icl shall not be used to represent multiple occupants whose clothing insulation differs by more than 0.15 clo. Exception to 5.2.2.1.2: Where individuals are free to adjust clothing to account for individual differences

in response to the thermal environment, it is permitted to use a single representative occupant with an average clothing insulation Icl value to represent multiple individuals. 5.2.2.2 Insulation Determination. Use one or a combination of the following methods to determine clothing insulation Icl :

a. Use the data presented in Table 5-2 for the expected ensemble of each representative occupant. b. Add or subtract the insulation of individual garments in Table 5-3 from the ensembles in Table 5-2 to

determine the insulation of ensembles not listed. c. Determine a complete clothing ensemble using the sum of the individual values listed for each item of

clothing in the ensemble in Table 5-3. d. It is permitted, but not required, to adjust any of the previous methods for seated occupants using Table

5-4. e. Interpolate between or extrapolate from the values given in Tables 5-3 and 5-4. f. Use Figure 5-1 to determine the clothing insulation Icl of a representative occupant for a day as a function of outdoor air temperature at 06:00 a.m., ta(out,6) .

Clothing insulation Icl determined in accordance with Figure 5-1 is permitted but not required to be adjusted to account for unique dress code or cultural norms using other methods in Section 5.2.2.2 or approved engineering methods. g. Use measurement with thermal manikins or other approved engineering methods.

6 ANSI/ASHRAE Standard 55-2023