ASHRAE Journal - June 2011 - 46

Evaluating Acceptable Thermal Conditions Using Standard 55-2010 Step 1 Evaluation Question Are expected met rates between 1.0 and 1.3 met and are expected clo values between 0.5 and 1.0 clo, to meet the limitations of the graphical method in Section 5.2.1.1? Are expected met rates between 1.0 and 2.0 met and are expected clo values 1.5 or less, to meet the limitations of the computer model method in Section 5.2.1.2? Is operative temperature, determined per Section 7 & Appendix C, within acceptable ranges in Figure 5.2.1.1-1 for expected clo value, per Graphical Method Section 5.2.1.1? Are assumed values for clo, met, design, air temperature, mean radiant temperature, relative air velocity, and relative humidity or water vapor pressure such that calculated PPD is under 10% (calculated PMV range is between –0.5 and +0.5), per Computer Model Method Section 5.2.1.1? Is humidity ratio controlled to below 0.012, per Humidity Limits, Section 5.2.2? If any increased air temperature or mean radiant temperature is expected, does elevated air speed offset this, per Elevated Air Speed, Section 5.2.3? Will wall and ceiling temperatures be within limits in Table 5.2.4.1, or is PD less than 5% using Figure 5.2.4.1, per Radiant Temperature Asymmetry Section 5.2.4.1? Will draft be within limits for air temperature and air speed per Section 5.2.4.2, or are elevated air speed requirements of Section 5.2.3 including local control met? Will temperature difference taken from ankle to head level be less than 3°C (5.4°F), per Vertical Air Temperature Difference Section 5.2.4.3? Will the floor temperature be between 19.0 and 29.0°C (66.2 and 84.2°F), per Floor Surface Temperature Section 5.2.4.4? Are there any expected changes in operative temperature with periods under 15 minutes less than 1.1°C (2.0°F), per Cyclic Variations Section 5.2.5.1? Are any components of variations in operative temperature with periods over 15 minutes within the respective limits in Table 5.2.5.2, per Drifts or Ramps Section 5.2.5.2? If Yes Proceed to Step 3 If No Proceed to Step 2 Unless space complies under Table 2 method for “Naturally conditioned spaces,” Standard 55-2010 does not apply. Same as Above

Proceed to Step 4

Proceed to Step 5

Proceed to Step 6

Same as Above Use computer method or adaptive method, if applicable. Same as Above

Proceed to Step 6

Proceed to Step 7

Proceed to Step 8

Same as Above

Proceed to Step 9

Same as Above

9 10 11

Proceed to Step 10 Proceed to Step 11 Proceed to Step 12

Same as Above Same as Above Same as Above

Proceed to Step 13

Same as Above

Must be completed to meet Have design and documentation compliance requirements in Section 6 been Recommendations in requirements of Standard met (see Appendix G for compliance documentation forms)? Standard 55-2010 are met. 55-2010.

Table 1: Use this table for evaluating compliance using Section 5.2, the Graphic Comfort Zone Method for Typical Indoor Environments and the Computer Model Method for General Indoor Application, for spaces being served by heating and mechanical cooling systems. ed air speed provisions can be applied when using the Graphical Comfort Zone Method. puter code that calculates these indices is in Appendix D of the standard, and is widely available from other sources. This approach allows users of the standard to predict the extent to which comfort will be provided based on a specific set of expected clothing level (clo), activity level (met), air temperature, radiant temperature, air speed, and humidity. The same additional requirements enumerated above for the Graphic Comfort Zone Method also apply to the Computer Model Method; the only difference is that instead of an absolute upper limit on humidity ratio, calculated limits pertain that allow, in certain conditions, even higher humidity. As stated previashrae.org June 2011

Computer Model Method
This method is the basis for the comfort zones drawn in the Graphic Comfort Zone Method, derived from the Predicted Mean Vote (PMV) and Predicted Percent Dissatisfied (PPD) indices developed by the late Professor Ole Fanger in his seminal doctoral thesis (first published in book form in 1970). The use of these indices as the basis for this method makes Standard 55-2010 consistent with ISO Standard 7730. The com46 ASHRAE Journal

ASHRAE Journal - June 2011

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