ANSI/ASHRAE Standard (Supersedes ANSI/ASHRAE Standard ) ASHRAE STANDARD Thermal Environmental Conditions. CBE Thermal Comfort tool to calculate thermal comfort according to ASHRAE Standard , ASHRAE standard 55 thermal comfort tool, thermal comfort. See Appendix I for approval dates by the ASHRAE Standards Committee, the ASHRAE an ASHRAE Standard may be purchased from the ASHRAE Web site .
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HP Standard Genera This standard is under continuous maintenance by a Standing Standard Project Committee SSPC for which the Standards Committee has established a documented program for regular publication of addenda or revisions, including procedures for timely, documented, consensus action on requests for change to any part of the standard.
Dougherty Hakim Elmahdy Matt R. Ramspeck, Manager of Standards Frank E. Nasseri Gideon Shavit David R. This signifies the concurrence of more than a simple majority, but not necessarily unanimity. Consensus requires that all views and objections be considered, and that an effort be made toward their resolution. ASHRAE obtains 55-22007 through participation of its national and international members, associated societies, and public review.
Every effort is made to balance the concerned interests on all Project Committees. In referring to this Standard or Guideline and in marking of equipment and in advertising, no claim shall be made, either stated or implied, that the product has been approved by ASHRAE. Acceptable Approximation for Operative Temperature It is merely informative and does not contain requirements necessary for conformance to the standard. Asrae has not been processed according to the ANSI requirements for a standard and may contain material that has not been subject to public review or a consensus process.
The standard specifies conditions in which a specified fraction of the occupants will find the environment thermally acceptable. The revision is a consensus standard that has undergone public and ASHRAE review; it incorporates the relevant research and experience gained since the revision. The standard is intended for use in design, commissioning, and testing of buildings and other occupied spaces and their HVAC systems and for the evaluation of thermal environments.
Because it is not possible to prescribe the metabolic rate of occupants, and because of variations in occupant clothing levels, operating setpoints for buildings cannot be practically mandated by this standard. The selected design criteria will influence the Ahrae system design and may also influence the building design.
Standard 55, Environmental Conditions for Occupancy_图文_百度文库
This standard may also be used for evaluation of existing thermal environments in buildings, during experimental conditions, and for the development and testing of products. This standard is in close agreement with ISO Standards and PURPOSE The purpose of this standard is to specify the combinations of indoor thermal environmental factors and personal factors that will produce ashtae environmental conditions acceptable to a majority of the occupants within the space.
Expressed in clo units. The definition of clothing insulation relates to heat transfer from the whole body and, thus, also includes the uncovered parts of the body, such as head and hands. The surface area of an average person is 1.
In this standard, this rate is expressed in met units. Turbulence intensity may also be expressed in percent i. The standard deviation is based on individual values of air speed that represent an average over no more than two seconds each. Any application of this standard must specify the space to which it applies or the locations within asheae space to which it applies, if not to the entire space.
Any application of this standard must identify the occupants who must have a residency of more than 15 minutes in the space to which it applies. The activity and clothing of the occupants must be considered in applying this standard. If the requirements are not met for some known set of occupants, then these occupants must be identified.
Any application of this standard must clearly state which of these sections is used. Additionally, all requirements of the applicable section, 5.
Because there are large variations, both physiologically and psychologically, from person to person, it is difficult to satisfy everyone ashrqe a space. The environmental conditions required for comfort are not the same for everyone. However, extensive laboratory and field data have been collected that provide the necessary statistical data to define conditions that a specified percentage of occupants will find thermally comfortable.
Section 5 of this standard is used to determine the thermal environmental conditions in a space that are necessary to achieve acceptance by a specified percentage of occupants of that space. There are six primary factors that must be addressed when defining conditions for thermal comfort. A number of other, secondary factors affect comfort in some circumstances. The six primary factors are listed below.
Thermal comfort – compliance
Complete descriptions of these factors are presented in Section ashare. Metabolic rate Clothing insulation Air temperature Radiant temperature Air speed Humidity to groups of occupants such as are found in classroom situations. However, the conditions required for thermal comfort in spaces that are naturally conditioned are not necessarily the same as those conditions required for other indoor spaces.
Field experiments have shown that in naturally conditioned spaces, where occupants have control of operable windows, the subjective notion of comfort is different because of different thermal experiences, availability of control, and resulting shifts in 55-2070 expectations. The methods of Section 5. This standard recommends a specific percentage of occupants that constitutes acceptability and values of the thermal environment associated with this percentage.
For given values of humidity, air speed, metabolic rate, and clothing insulation, a comfort zone may be ashra. The comfort zone is defined in terms of a range of operative temperatures that provide acceptable thermal environmental conditions or in terms of the combinations of air temperature and mean radiant temperature that people find thermally acceptable.
This section describes methods that may be used to determine temperature limits for the comfort zone. For a given set of conditions, the results from the two methods are consistent, and either method may be used as long as the criteria outlined in the respective section are met.
Dry-bulb temperature may be used as a proxy for operative temperature under certain conditions described in Appendix C. The method in this section may be applied to spaces where the occupants have activity levels that result in metabolic rates between 1. See Appendix A for estimation of metabolic rates and Appendix B for estimation of clothing insulation. Most office spaces fall within these limitations.
The range of operative temperatures presented in Figure 5.
ASHRAE 55 – Wikipedia
However, this standard only addresses thermal comfort in a steady state with some limited specifications for temperature variations with time in Section 555-2007.
As a result, people entering a space that meets the requirements ashgae this standard may not immediately find the conditions comfortable if they have experienced different environmental conditions just prior to entering the space. The effect of prior exposure or activity may affect comfort perceptions for approximately one hour. Factors 2 through 6 may be nonuniform over an occupant’s body, and this nonuniformity may be an important consideration in determining thermal comfort.
Nonuniformity is addressed in Section 5. The vast majority of the available thermal comfort data pertains to sedentary or near sedentary physical activity levels typical of office work.
This standard is intended primarily for these conditions. However, it may also be used to determine appropriate environmental conditions for ashre elevated activity.
It does wshrae apply to sleeping or bed rest. The body of available data does not contain significant information regarding the comfort requirements of children, the disabled, or the infirm.
Two zones are shown—one for 0. These insulation levels are typical of clothing worn when the outdoor environment is warm and cool, respectively. The operative temperature range allowed for intermediate values of clothing insulation may be determined by linear interpolation between the limits for 0. The ASHRAE thermal sensation scale, which was developed for use in quantifying people’s thermal sensation, is defined as follows: Air speeds greater than 0.
The method in this section may be applied to spaces where the occupants have activity levels that result in average metabolic rates between 1. This is the basis for the graphical method in Section 5. The comfort zone is defined by the combinations of air temperature and mean radiant temperature for which the PMV is within the recommended limits specified in Table 5. The PMV model is calculated with the air temperature and mean radiant temperature in question along with the applicable metabolic rate, clothing insulation, air speed, and humidity.
If the resulting PMV value generated by the model is within the recommended range, the conditions are within the comfort zone.
Use of the PMV model in this standard is limited to air speeds not greater than 0. The ashdae in Section 5. The computer code in Appendix D is to be used with this standard. Systems designed to control humidity shall be able to maintain a humidity ratio at or below 0. There are no ashrea lower humidity limits for thermal comfort; consequently, this standard does not specify a minimum humidity level. However, non-thermal comfort factors, such as skin drying, irritation of mucus membranes, dryness of the eyes, and static electricity generation, may place limits on the acceptability of very low humidity environments.
Precise relationships between increased air speed and aehrae comfort have not been established. However, this standard allows elevated air speed to be used to increase the maximum temperature for acceptability if the affected occupants are able to control the air speed. The amount that the temperature may be increased is ahrae in Figure 5. The combinations of air speed and temperature defined by the lines in this figure result in the same heat loss from the skin.
Standard 55 – Thermal Environmental Conditions for Human Occupancy
This figure applies to a lightly clothed person with clothing insulation between 0. The indicated increase in temperature pertains to both the mean radiant temperature and the air temperature. That is, both temperatures increase by the same amount with respect to the starting point.
When the mean radiant temperature is low and the air temperature is high, elevated air speed is less effective at increasing heat loss. Conversely, elevated air speed is more effective at increasing heat 55-2070 when the mean radiant temperature is high and the air temperature is low.
Thus, the curve asheae Figure 5. It is acceptable to interpolate between curves for intermediate differences.
Elevated air speed may be used to offset an increase in the air temperature and the mean radiant temperature, but not by more than 3. The required air speed may not be higher than 0. Large individual differences exist between people with regard to the preferred air speed. Therefore, the elevated air speed must be under the direct control of the affected occupants and adjustable in steps no greater than 0.
The benefits that can be gained by increasing air speed depend on clothing and activity. Due to increases in skin wettedness, the effect of increased 555-2007 is greater with elevated activity than with sedentary activity.
Due to increased amounts of exposed skin, the effect of increased air speed is greater with lighter clothing.