ASHRAE-Standard-55 - Page 048

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(This appendix is not part of this standard. It is merely informative and does not contain requirements necessary for conformance to the standard. It has not been processed according to the ANSI require- ments for a standard and may contain material that has not been subject to public review or a consen- sus process. Unresolved objectors on informative material are not offered the right to appeal at ASHRAE or ANSI.)

INFORMATIVE APPENDIX G CLOTHING INSULATION

The amount of thermal insulation worn by a person has a substantial impact on thermal comfort and is an important variable in applying this standard. Clothing insulation is expressed in a number of ways. In this standard, the clothing insulation Icl of an ensemble expressed as a clo value is used. Users not familiar with clothing insulation terminology should refer to ASHRAE Handbook—Fundamentals [ 1], Chapter 9, for more information.

The insulation provided by clothing can be determined by a variety of means, and if accurate data are available from other sources, such as measurement with thermal manikins, these data are acceptable for use. When such information is not available, the tables in this standard may be used to estimate clothing insulation Icl using one of the methods described below. Regardless of the source of the clothing insulation value, this standard is not intended for use with clothing ensembles with more than 1.5 clo of insulation, nor is it intended for use when occupants wear clothing that is highly impermeable to moisture transport (e.g., chemical protective clothing or rain gear).

Four methods for estimating clothing insulation Icl are presented. Methods 1, 2, and 3 are listed in order of accuracy. The tables used in the standard are derived from ASHRAE Handbook—Fundamentals [1], Chapter 9.

 - **Method 1:** Table 5-2 of this standard lists the insulation provided by a variety of common clothing

ensembles. If the ensemble in question matches reasonably well with one of the ensembles in this table, then the indicated value of Icl should be used.

 - **Method 2:** Table 5-3 of this standard presents the thermal insulation of a variety of individual garments. It

is acceptable to add or subtract these garments from the ensembles in Table 5-2 to estimate the insulation of ensembles that differ in garment composition from those in Table 5-2. For example, if long underwear bottoms are added to Ensemble 5 in Table 5-2, the insulation of the resulting ensemble is estimated as

Icl = 1.01 + 0.15 = 1.16 clo

 - **Method 3:** It is acceptable to define a complete clothing ensemble using a combination of the garments

listed in Table 5-3 of this standard. The insulation of the ensemble is estimated as the sum of the individual values listed in Table 5-3. For example, the estimated insulation of an ensemble consisting of overalls worn with a flannel shirt, t-shirt, briefs, boots, and calf-length socks is

Icl = 0.30 + 0.34 + 0.08 + 0.04 + 0.10 + 0.03 = 0.89 clo

 - **Method 4:** It is acceptable to determine the clothing insulation _Icl_ with Figure 5-1 in mechanically conditioned buildings. When people select their clothing as a function of outdoor and indoor climate variables,

the most influential variable is outdoor air temperature. Figure 5-1 can be used to calculate the clothing insulation for each day of the year or for representative days. The curve in Figure 5-1 is an approximation for typical (or average) clothing. The model is based on field study and may not be appropriate for all cultures and occupancy types. The model represented in Figure 5-1 is suited to be implemented in building performance simulation software or building control systems. The model graphed in Figure 5-1 is described by the following equations:

For ta(out,6) < –5°C Icl = 1.00

For –5°C  ta(out,6) < 5°C Icl = 0.818 – 0.0364 × ta(out,6)

For 5°C  ta(out,6) < 26°C Icl = 10 [(–0.1635 – 0.0066 × ] [ta(out,6)] [)]

or ta(out,6)  26°C Icl = 0.46

For ta(out,6) < 23°F Icl = 1.00

For 23°F  ta(out,6) < 41°F Icl = 1.465 – 0.0202 × ta(out,6)

For 41°F  ta(out,6) < 78.8°F Icl = 10 [(–0.0460 – 0.00367 × ] [ta(out,6)] [)]

or ta(out,6)  78.8°F Icl = 0.46

46 ANSI/ASHRAE Standard 55-2023