ASHRAE-Standard-55 - Page 024
Extracted Content
7.2.2.1 Mechanically Conditioned Spaces. Use Section 5.3 to determine the comfort of occupants under the measured environmental conditions. Clothing and activity levels of the occupants must be as observed or as expected for the use of the indoor space in question. Use Section 5.3.4 to adjust the comfort zone’s lower and upper operative temperature limits for elevated air movement. Occupied zone conditions must also conform to requirements for avoiding local thermal discomfort (as specified in Section 5.3.5) and to limits to rate of temperature change over time, as specified in Section 5.3.6.
Parameters to be measured and/or recorded include the following:
a. Occupant metabolic rate (met) and clothing (clo) observations b. Air temperature and humidity c. Mean radiant temperature tr, unless it can be otherwise demonstrated that, within the space, tr is within 1°C (2°F) of ta d. Air speed, unless it can be otherwise demonstrated that, within the space, average air speed Va meets the
tr, unless it can be otherwise demonstrated that, within the space, tr
requirements of Section 5.3.4 e. Control measures for environmental factors
7.2.2.2 Occupant-Controlled Naturally Conditioned Spaces. Section 5.4 prescribes the use of the adaptive model for determining the comfort zone boundaries. The air movement extensions to the comfort zone’s lower and upper operative temperature limits (Table 5-12) shall be used when elevated air movement is present.
Parameters to be measured include the following:
a. Indoor air temperature and mean radiant temperature b. Outdoor air temperature
tr
7.3 Measurement Methods 7.3.1 Surveys of Occupant Responses to Environment. Surveys shall be solicited from the entire occupancy or a representative sample thereof. If more than 45 occupants are solicited, the response rate must exceed 35%. If solicited occupants number between 20 and 45, at least 15 must respond. For under 20 solicited occupants, 80% must respond. Informative Note: Refer to Informative Appendix L for further discussion of surveys, including examples.
7.3.1.1 Satisfaction Surveys
a. Thermal satisfaction shall be measured with a scale ending with the choices “very dissatisfied” and “very
satisfied.” b. Thermal satisfaction surveys shall include diagnostic questions allowing causes of dissatisfaction to be
identified.
7.3.1.2 Point-in-Time Surveys. Point-in-time surveys shall be solicited during times representative of the building’s occupancy.
a. Thermal satisfaction questions shall include a continuous or seven-point scale ending with the choices
“very dissatisfied” and “very satisfied.” b. Thermal sensation questions shall include the ASHRAE seven-point thermal sensation scale subdivided
as follows: cold, cool, slightly cool, neutral, slightly warm, warm, hot. c. Thermal preference questions shall use the three-point scale “cooler,” “without change,” and “warmer.”
7.3.2 Physical Measurement Positions within the Building
a. Floor plan: Thermal environment measurements shall be made in the building at a representative sample
of locations where the occupants are known to, or are expected to, spend their time. When performing evaluation of similar spaces in a building, it shall be permitted to select a representative sample of such spaces.
If occupancy distribution cannot be observed or estimated, the measurement locations shall include both of the following:
- The center of the room or space
- 1.0 m (3.3 ft) inward from the center of each of the room’s walls. In the case of exterior walls with windows, the measurement location shall be 1.0 m (3.3 ft) inward from the center of the largest window. Measurements shall also be taken in locations where the most extreme values of the thermal parameters are observed or estimated to occur (e.g., potentially occupied areas near windows, diffuser outlets, corners, and entries).
22 ANSI/ASHRAE Standard 55-2023