ANSIASHRAE Standard 55-2020 Addendum h: Condições Ambientais Térmicas

ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 Thermal Environmental Conditions for Human Occupancy Approved by ASHRAE and the American National Standards Institute on December 30 2022 This addendum was approved 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 docu mented consensus action on requests for change to any part of the standard Instructions for how to submit a change can be found on the ASHRAE website wwwashraeorgcontinuousmaintenance The latest edition of an ASHRAE Standard may be purchased on the ASHRAE website wwwashraeorg or from ASHRAE Customer Service 180 Technology Parkway Peachtree Corners GA 30092 Email ordersashraeorg Fax 6785392129 Telephone 4046368400 worldwide or toll free 18005274723 for orders in US and Canada For reprint permission go to wwwashraeorgpermissions 2022 ASHRAE ISSN 10412336 ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ASHRAE is a registered trademark of the American Society of Heating Refrigerating and AirConditioning Engineers Inc ANSI is a registered trademark of the American National Standards Institute SPECIAL NOTE This American National Standard ANS is a national voluntary consensus Standard developed under the auspices of ASHRAE Consensus is defined by the American National Standards Institute ANSI of which ASHRAE is a member and which has approved this Standard as an ANS as substantial agreement reached by directly and materially affected interest categories 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 Compliance with this Standard is voluntary until and unless a legal jurisdiction makes compliance mandatory through legislation ASHRAE obtains consensus through participation of its national and international members associated societies and public review ASHRAE Standards are prepared by a Project Committee appointed specifically for the purpose of writing the Standard The Project Committee Chair and ViceChair must be members of ASHRAE while other committee members may or may not be ASHRAE members all must be technically qualified in the subject area of the Standard Every effort is made to balance the concerned interests on all Project Committees The Senior Manager of Standards of ASHRAE should be contacted for a interpretation of the contents of this Standard b participation in the next review of the Standard c offering constructive criticism for improving the Standard or d permission to reprint portions of the Standard DISCLAIMER ASHRAE uses its best efforts to promulgate Standards and Guidelines for the benefit of the public in light of available information and accepted industry practices However ASHRAE does not guarantee certify or assure the safety or performance of any products components or systems tested installed or operated in accordance with ASHRAEs Standards or Guidelines or that any tests conducted under its Standards or Guidelines will be nonhazardous or free from risk ASHRAE INDUSTRIAL ADVERTISING POLICY ON STANDARDS ASHRAE Standards and Guidelines are established to assist industry and the public by offering a uniform method of testing for rating purposes by suggesting safe practices in designing and installing equipment by providing proper definitions of this equipment and by providing other information that may serve to guide the industry The creation of ASHRAE Standards and Guidelines is determined by the need for them and conformance to them is completely voluntary 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 ASHRAE Standing Standard Project Committee 55 Cognizant TC 21 Physiology and Human Environment SPLS Liaison David Robin David Heinzerling Chair and Webmaster Essam E Khalil David M Rose Josh Eddy Secretary Baizhan Li Stefano Schiavon Peter F Alspach Shichao Liu Lawrence J Schoen Edward A Arens Rodrigo Mora Peter Simmonds Robert Bean Abhijeet Pande Amy L Stadler Thomas B Hartman Zaccary A Poots Federico Tartarini Ongun B Kazanci Daniel J Rice Joyce Kim Julian Rimmer Denotes members of voting status when the document was approved for publication ASHRAE STANDARDS COMMITTEE 20222023 Susanna S Hanson Chair Gerald J Kettler Gwelen Paliaga Jonathan Humble ViceChair Jay A Kohler Karl L Peterman William P Bahnfleth Cesar L Lim Justin M Prosser Thomas E Cappellin Paul A Lindahl Jr David Robin Douglas D Fick James D Lutz Christopher J Seeton Patricia Graef Julie Majurin Christian R Taber Jaap Hogeling Lawrence C Markel Paolo M Tronville Jennifer A Isenbeck Patrick C Marks William F Walter Phillip A Johnson Margret M Mathison Steven C Sill BOD ExO Srinivas Katipamula Kathleen Owen Sarah E Maston CO Connor Barbaree Senior Manager of Standards ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 1 This foreword 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 FOREWORD Addendum h to Standard 552020 makes multiple changes to the standard including the following Adds a new definition for comfort zone and updates related definitions Removes the concept of a separate elevated airspeed method and replaces it with a reference to an adjustment to the standard method This change includes edits to Appendix A where a flow chart is added to guide users through the various models that underpin the standard Replaces the word acceptable with satisfactory throughout the standard Rewrites Appendix H to account for recent changes in the standard and to better explain the concept of comfort zones Updates the example surveys provided in Appendix L and associated language Note In this addendum changes to the current standard are indicated in the text by underlining for additions and strikethrough for deletions unless the instructions specifically mention some other means of indicating the changes Modify Section 1 as shown 1 PURPOSE The purpose of this standard is to specify the combinations of indoor thermal environmental factors and per sonal factors that will produce satisfactory thermal environmental conditions acceptable to for a majority of the occupants within the space Modify Section 3 as shown below The remainder of Section 3 is unchanged comfort thermal comfort that condition of mind that expresses satisfaction with the thermal environment and is assessed by subjective evaluation environment acceptable satisfactory thermal a thermal environment that a substantial majority more than 80 of the occupants find thermally acceptablesatisfactory thermal zone thermal an area of a building designated by the designer such that the comfort zone is main tained within the occupied zone by local controls for its representative occupants zone comfort zone those combinations of air temperature mean radiant temperature tr and humidity that are predicted to be an acceptable thermal environment at particular values of air speed metabolic rate and clothing insulation Icl a zone whose boundaries enclose sets of environmental and personal conditions that provide thermal satisfaction according to the standard Remove Table 55 as shown below Modify Section 53 as shown The remainder of Section 53 is unchanged 53 Method for Determining Acceptable Satisfactory Thermal Environment in Occupied Spaces Addendum h to Standard 552020 Table 55 Applicability of Methods for Determining Acceptable Thermal Environments in Occupied Spaces Average Air Speed ms fpm Humidity Ratio met clo Comfort Zone Method 020 40 All 10 to 20 0 to 15 Section 531 Analytical Comfort Zone Method 020 40 All 10 to 20 0 to 15 Section 532 Elevated Air Speed Comfort Zone Method ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 2 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 531 Applicability Section 53 is permitted to be used to determine the requirements for thermal comfort in all occupied spaces within the scope of this standard See Sections 5214 and 5223 for limits to the occupants clothing and activity levels Acceptable thermal environments shall be determined using one of the two methods shown in Table 55 and any applicable requirements of Sections 533 and 534 Informative Note Average air speed and average air temperature have precise definitions in this stan dard See Section 3 for all defined terms 531 Analytical Comfort Zone Method 5311 Applicability It is permissible to apply the method in this section to all spaces within the scope of this standard where the occupants have activity levels that result in average metabolic rates between 10 and 40 met clothing insulation Icl between 00 and 15 clo and average air speeds Va greater than 010 ms 20 fpm 53212 Methodology The computer code in Normative Appendix B is to be used with this standard The PMV model with adjustments for solar radiation and elevated air speed is used to determine the bound aries of the comfort zone Compliance with Section 53 is achieved if 05 PMV 05 and the require ments of Sections 535 and 536 are met See Section 6 for full design compliance requirements A computer code implementation of the PMV model is provided in Normative Appendix B The adjust ment for solar radiation is described per Section 533 and Normative Appendix C The adjustment for ele vated air speed is described in Section 534 and Normative Appendix D Normative Appendices A B C and D provide the full methodology to comply with this section includ ing computer code implementations The Thermal Comfort Tool3 includes these methods and is permitted to be used to comply with this section Alternative calculation methods are permitted but If any other method is used it is the users responsibility to verify and document that the method used yields the same results The Thermal Comfort Tool3 is permitted to be used to comply with this section Figures 52 and 53 provides graphical examples of comfort zones using the PMV model in stillair con ditionsAnalytical Comfort Zone Method Direct use of these charts to comply with the Analytical Comfort Zone Methodthis section is allowable for the specific input conditions described on each chart In each fig ure the darker shade comfort zone is the same and the lighter shade comfort zone represents a single altered input a clothing insulation and b metabolic rate Informative Note See Informative Appendix L for further explanation of predicted mean vote PMV and its relationship to predicted percentage dissatisfied PPD 533121 Solar Radiation Adjustment When directbeam solar radiation falls on a representative occu pant the mean radiant temperature shall account for longwave mean radiant temperature and short wave mean radiant temperature using one of the following options 532 Elevated Air Speed Comfort Zone Method 5321 Applicability It is permissible to apply the method in this section to all spaces within the scope of this standard where the occupants have activity levels that result in average metabolic rates between 10 and 20 met clothing insulation Icl between 00 and 15 clo and average air speeds Va greater than 020 ms 40 fpm 5322 Methodology The calculation method in Normative Appendix D is to be used with this method This method uses the Analytical Comfort Zone Method in Section 531 combined with the Standard Effec tive Temperature SET model described in Normative Appendix D Figure 54 represents two particular cases 05 and 10 clo of the Elevated Air Speed Comfort Zone Method and shall be permitted as a method of compliance for the conditions specified in the figure The fig ure also defines comfort zones for air movement with occupant control darkly shaded Section 5323 ver sus without occupant control lightly shaded Section 5324 It is permissible to determine the operative temperature range by linear interpolation between the limits found for each zone in Figure 54 Figure 55 provides a graphical example of a comfort zone using the Elevated Air Speed Comfort Zone Method lighter shade zone Section 5323 compared to one using the Analytical Comfort Zone Method darker shade zone Section 531 Direct use of this chart to comply with the Elevated Air Speed Comfort Zone Method using the lighter shade zone is allowable for the specific input conditions described on the chart Alternative methods are permitted If any other method is used the user shall verify and document that the method used yields the same results The Thermal Comfort Tool 3 is permitted to be used to comply with this section When directbeam solar radiation falls on a representative occupant the mean radiant temperature shall account for longwave mean radiant temperature and shortwave mean radiant temperature in accordance with Section 53121 Figure 56 describes the steps for determining the limits to air speed inputs in SET model tr trlw trsw tr trlw trsw ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 3 534 Elevated Air Speed Adjustment For air speeds above 01 ms 20 fpm the Standard Effective Tem perature SET model is used in conjunction with the PMV model as described in Normative Appendix D Figure 54 represents two particular cases 05 and 10 clo of the comfort zone across the range of indoor air speeds and shall be permitted as a method of compliance for the conditions specified in the fig ure The figure also defines comfort zones for air movement with occupant control darkly shaded Section 5341 versus without occupant control lightly shaded Section 5342 It is permissible to determine the operative temperature range by linear interpolation between the limits found for each zone in Figure 54 Figure 55 provides a graphical example of comfort zones for two air speeds Direct use of this chart to comply with the standard is allowable for the specific input conditions described on the chart Figure 56 describes the steps for determining the limits to air speed inputs Modify captions for Figures 52 53 54 55 56 as shown Figure 52 Analytical Comfort Zzone Method exampleeffect of increased clo value Figure 53 Analytical Comfort Zzone Method exampleeffect of increased met value Figure 54 Acceptable Satisfactory ranges of operative temperature to and average air speed Va for 10 and 05 clo comfort zones at humidity ratio 0010 Figure 55 Elevated Aair Sspeed Ccomfort Zzone Method example lightly shaded zone compared to the Analytical stillair Ccomfort Zzone Method example darkly shaded zone Figure 56 Flowchart for determining limits to air speed inputs in the Eelevated Aair Sspeed Ccomfort Zzone Method Modify subsequent headings of Section 53 and associated references within the standard as shown 532431 Average Air Speed Va with Occupant Control Section 53253442 does not apply when the occupants have control over average air speed Va and one of the following criteria is met 534224 Average Air Speed Va without Occupant Control If occupants do not have control over the local air speed meeting the requirements of Section 53253431 the following limits apply to the SET model and to Figure 54 Exceptions 534224c 5335 Local Thermal Discomfort 53531 Applicability The requirements specified in this section are required to be met only when rep resentative occupants meet both of the following criteria 53352 Radiant Temperature Asymmetry 53533 Ankle Air Speed Exception to 53353 The requirement in this section does not apply when using elevated air speed in Section 533535 53534 Vertical Air Temperature Gradient Air temperature gradient between head level and ankle level shall not exceed the value resulting from the following formula or in the shaded region of Figure 5 735 Exception to 5335354 The requirement in this section does not apply when using elevated air speed in Section 533535 Informative Note Refer to the informative note in Section 5335351 5335355 Floor Surface Temperature When representative occupants are seated with feet in contact with the floor floor surface temperatures within the occupied zone shall be 19C to 29C 662F to 842F 534536 Temperature Variations with Time 5345361 Applicability The fluctuation requirements of this section shall be met when they are not under the direct control of the individual occupant 5345362 Cyclic Variations Cyclic variations in operative temperature to that have a period not greater than 15 minutes shall have a peaktopeak amplitude not greater than 11C 20F ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 4 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 5345363 Drifts or Ramps Monotonic noncyclic changes in operative temperature to and cyclic variations with a period greater than 15 minutes shall not exceed the most restrictive requirements from Table 512 Modify Section 6 as shown The remainder of Section 6 is unchanged 611 Design Thermal Environmental Control Classification For all projects demonstrating compli ance through Section 531 532 or 533 design compliance shall indicate the Thermal Environmental Control Classification Level in accordance with Table 61 of each space type within the building 62 Documentation The method and design conditions appropriate for the intended use of the building shall be selected and documented as follows Informative Note Some of the requirements in items a through h below are not applicable to naturally conditioned buildings a The method of design compliance shall be stated for each space andor system Analytical Comfort Zone Method Section 531 Elevated Air Speed Comfort Zone Method Section 532Section 53 or the use of Section 54 for occupantcontrolled naturally conditioned spaces b The design operative temperature to and humidity including any tolerance or range the design outdoor conditions see ASHRAE HandbookFundamentals1 Chapter 14 and total indoor loads shall be stated The design exceedance hours Informative Note see Section 3 Definitions shall be documented based on the design conditions used c Values assumed for comfort parameters used in the calculation of thermal conditions including operative temperature to humidity average air speed Va clothing insulation Icl and metabolic rate shall be stated for heating and cooling design conditions If an acceptable a satisfactory level of comfort is not being provided to any representative occupants this shall be stated Where Table 51 gives a range the basis for selecting a single value within that range shall be stated If the clothing insulation or metabolic rate parameters for a given space are outside the applicable bounds defined by the standard or if the space is not regularly occupied as defined in Section 23 the space shall be clearly identified as not under the scope of the standard d Local thermal discomfort shall be addressed at a minimum by a narrative explanation of why an effect is not likely to exceed Section 5 limits Where calculations are used to determine the effect of local ther mal discomfort in accordance with Section 5 the calculation inputs methods and results shall be stated e System equipment capacity shall be provided for each space andor system documenting performance meeting the design criteria stated For each unique space the design system or equipment heating andor cooling capacity shall meet the thermal loads calculated under the heating and cooling design conditions stated for compliance with this standard f Where elevated air speed with occupant control is employed to provide acceptable satisfactory thermal conditions documentation shall be provided to identify the method and equipment for occupant control g Air speed radiant temperature asymmetry vertical airtemperature difference surface temperatures and temperature variations with time shall be determined in accordance with generally accepted engineering standards eg ASHRAE HandbookHVAC Applications Chapter 57 The method used and quantified selection criteria characteristics sizes and indices that are applicable to the method shall be stated h When directbeam solar radiation falls on a representative occupant documentation shall include solar design condition solar altitude direct beam intensity the method in Section 531213 used for compli ance and the resultant mean radiant temperature i Thermal Environmental Control Classification Level shall be documented for each space type with sup porting calculations and design documents indicating the control measures for environmental factors the means of control and the degree to which control changes the environmental factor Modify Section 7 as shown The remainder of Section 7 is unchanged 721 Comfort Determination from Occupant Surveys Acceptability and sSatisfaction areis directly determined from the responses of occupants using the scales and comfort limits described in Section 731 7221 Mechanically Conditioned Spaces Use Section 531 Analytical Comfort Zone Method to determine the comfort of occupants under the measured environmental conditions Clothing and activity lev els of the occupants must be as observed or as expected for the use of the indoor space in question Use Sec tr ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 5 tion 5324 to adjust the comfort zones lower and upper operative temperature limits for elevated air movement Occupied zone conditions must also conform to requirements for avoiding local thermal discom fort as specified in Section 533535 and to limits to rate of temperature change over time as specified in Section 534536 Parameters to be measured andor recorded include the following a Occupant metabolic rate met and clothing clo observations b Air temperature and humidity c Mean radiant temperature unless it can be otherwise demonstrated that within the space is within 1C 2F of ta d Air speed unless it can be otherwise demonstrated that within the space average air speed Va meets the requirements of Section 5324 e Control measures for environmental factors 73 Measurement Methods 731 Surveys of Occupant Responses to Environment Surveys shall be solicited from the entire occu pancy 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 solic ited occupants 80 must respond Informative Note Refer to Informative Appendix L for further discussion of surveys including examples 7312 PointinTime Surveys Pointintime surveys shall be solicited during times representative of the buildings occupancy a Thermal acceptability satisfaction questions shall include a continuous or sevenpoint scale ending with the choices very unacceptabledissatisfied and very acceptablesatisfied b Thermal sensation questions shall include the ASHRAE sevenpoint thermal sensation scale subdivided as follows cold cool slightly cool neutral slightly warm warm hot c Thermal preference questions shall use the threepoint scale cooler without change warmer Pointintime surveys shall be solicited during times representative of the buildings occupancy 732 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 1 The center of the room or space 2 10 m 33 ft inward from the center of each of the rooms walls In the case of exterior walls with win dows the measurement location shall be 10 m 33 ft inward from the center of the largest window Measurements shall also be taken in locations where the most extreme values of the thermal parame ters are observed or estimated to occur eg potentially occupied areas near windows diffuser outlets corners and entries b Height above floor Air temperature and average air speed Va shall be measured at the 01 06 and 11 m 4 24 and 43 in levels for seated occupants at the plan locations specified in Section 732a1 and 732a2 Measurements for standing occupants shall be made at the 01 11 and 17 m 4 43 and 67 in levels and measurements for horizontal occupants shall be made at the mean height of the body Oper ative temperature to or PMV shall be measured or calculated at the 06 m 24 in level for seated occu pants the 11 m 43 in level for standing occupants and the mean height of the body for horizontal occupants Floor temperature that may cause local discomfort shall be measured at the surface by contact thermometer or infrared thermometer Section 5335355 Radiant temperature asymmetry that may cause local thermal discomfort Section 5335354 shall be measured in the affected occupants locations with the sensor oriented the greatest surface tempera ture difference tr tr ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 6 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 741 Evaluation Based on Survey Results a The probability percentage of occupants satisfied shall be predicted calculated from sevenpoint satisfac tion survey scores by dividing the number of votes falling between 1 and 3 inclusive by the total number of votes Responses to diagnostic dissatisfaction questions shall be tallied by category b For pointintime surveys comfort shall be evaluated using votes on the acceptability satisfaction andor thermal sensation scales On the acceptability satisfaction scale votes between 10 neutralslightly satis fied and 3 very acceptablesatisfied inclusive shall be divided by total votes to obtain the probabil ity percentage of comfort acceptabilitythermal satisfaction observed during the survey period On the sevenpoint thermal sensation scale votes between 15 and 15 inclusive shall be divided by total votes to obtain the probability percentage of comfort acceptabilitythermal satisfaction observed during the survey period 7421 Approaches to Predicting whether a Thermal Environment is Acceptable Satisfactory at a Specific Instance in Time a Mechanically conditioned buildings 1 Occupied spaces shall be evaluated using the PMV and SET comfort zone as defined in Sections 532534 2 Local thermal discomfort shall be evaluated using the limits to environmental asymmetry prescribed in Section 533535 b Buildings with occupantcontrolled operable windows 1 Occupied spaces shall be evaluated using the indoor operative temperature to contours of the adaptive model comfort zone in Section 54 including the contour extensions for average air speeds Va above 03 ms 59 fpm 7422 Approaches to Predicting whether a Thermal Environment is Acceptable Satisfactory over Time ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 7 Modify Normative Appendix A as shown The remainder of Normative Appendix A is unchanged NORMATIVE APPENDIX A OPERATIVE TEMPERATURE AND PROCEDURE FOR SECTION 53 A1 METHODS FOR DETERMINING OPERATIVE TEMPERATURE A2 PROCEDURE FOR DETERMINING SATISFACTORY THERMAL ENVIRONMENT IN OCCUPIED SPACES PER SECTION 53 The PMV model with adjustments for solar radiation and elevated air speed is used to determine the bound aries of the comfort zone per the calculation methods described in Appendices B through D These calcula tion methods are incorporated in the Thermal Comfort Tool3 The flowchart in Figure A1 provides the procedure for how these calculation methods should be applied Figure A1 Flowchart describing process of calculation methods used in Section 53 ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 8 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 Modify Normative Appendix B as shown The remainder of Normative Appendix B is unchanged NORMATIVE APPENDIX B COMPUTER PROGRAM FOR CALCULATION OF PMVPPD The following code is one implementation of the PMVPPD calculation using JavaScript in SI units This calculation does not include discomfort risk due to local discomfort factors The input variable clo in the PMV function shall be calculated using the following equation clo Icl 06 04M for M 12 clo Icl for M 12 where M is the metabolic rate in met units and Icl is the clothing insulation The input variable vel in the PMV function is the sum of the average air speed V plus the activitygen erated air speed Vag ms Where Vag is the activitygenerated air speed caused by motion of individual body parts ms It is a function of metabolic rate and is added to the average air speed to determine convec tive cooling of the body Vag is assumed to be 0 for metabolic rates equal and lower than 1 met and otherwise equal to Modify Normative Appendix D As shown The remainder of Normative Appendix D is unchanged D1 CALCULATION OVERVIEW Section 53 requires that the Eelevated Aair Sspeed adjustmentComfort Zone Method be used when average air speed Va is greater than 010 ms 40 fpm The SET model shall be used to account for the cooling effect of air speeds greater than the maximum allowed in the Analytical Comfort Zone Methods This appendix describes the calculation procedures for the Eelevated Aair Sspeed adjustmentComfort Zone Method Modify Informative Appendix E as shown The remainder of Informative Appendix E is unchanged E1 INTRODUCTION Thermal comfort is that condition of mind that expresses satisfaction with the thermal environment Because there are large variations physiologically and psychologically from person to person it is difficult to satisfy everyone in a space The environmental conditions required for comfort are not the same for everyone Extensive laboratory and field data have been collected that provide the necessary statistical information to define conditions that a specified percentage of occupants will find thermally comfortable Note that the pairs of terms satisfactionacceptability satisfactoryacceptable and are satisfied withaccept are each considered synonymous in the standard though the standard uses satisfaction as its standard nomenclature E3 VARIATION AMONG OCCUPANTS In some cases it will not be possible to achieve an acceptablea satisfactory thermal environment for all occupants of a space due to individual differences including activity andor clothing If the requirements are not met for some known set of occupants then the standard requires that these occupants be identified E4 TEMPORAL VARIATION It is possible for all six primary factors to vary with time This standard only addresses thermal comfort in a steady state with some limited specifications for temperature variations with time in Section 534536 E5 LOCAL THERMAL DISCOMFORT Nonuniformity is addressed in Section 533535 Factors 1 through 6 may be nonuniform over an occu pants body and this nonuniformity may be an important consideration in determining thermal comfort ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 9 Modify Informative Appendix H as shown INFORMATIVE APPENDIX H COMFORT ZONES DEFINING SATISFACTORY THERMAL CONDITIONS IN OCCUPIED SPACESCOMFORT ZONE METHODS H1 DETERMINING ACCEPTABLE THERMAL CONDITIONS IN OCCUPIED SPACESINTRODUCTION 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 determined The comfort zone is defined in terms of a range of operative temperatures to that provide acceptable thermal environmental conditions or in terms of the combinations of air temperature and mean radiant temperature that people find thermally acceptable See Normative Appendix A and ASHRAE HandbookFundamentals1 Chapter 9 for procedures to calculate operative temperature to Drybulb temperature is a proxy for operative temperature under certain conditions described in Normative Appendix A This standard generates comfort zones within the ranges of environmental and personal conditions likely to be found indoors The boundaries of comfort zones enclose sets of conditions that are considered satisfac tory by their occupancies They are based on predicted values of how occupants on average evaluate their thermal sensationspecifically their sense of the environment being warm or cool Thermal sensation is individually measured by pointintime survey questionnaires using the ASHRAE sevenpoint thermal sen sation scale 3 Hot 2 Warm 1 Slightly warm 0 Neutral 1 Slightly cool 2 Cool 3 Cold Because groups of people in a given environment exhibit considerable variance in their thermal sensa tion votes the mean thermal sensation vote is needed to characterize each combination of environmental and personal conditions In the standard this mean vote is predicted using the predicted mean vote PMV model given in Appendix B The PMV model calculates the heat balance of a specified occupant and relates their thermal gains or losses to their predicted mean thermal sensation H2 ANALYTICAL COMFORT ZONE METHOD This method applies to spaces where the occupants have activity levels that result in average metabolic rates between 10 and 40 met and where clothing is worn that provides 15 clo or less of thermal insulation The ASHRAE thermal sensation scale which was developed for use in quantifying peoples thermal sen sation is defined as follows 3 Hot 2 Warm 1 Slightly warm 0 Neutral 1 Slightly cool 2 Cool 3 Cold The predicted mean vote PMV model uses heat balance principles to relate the six key factors for ther mal comfort to the average response of people on the above scale The predicted percentage dissatisfied PPD index is related to the PMV as defined in Figure H1 It is based on the assumption that people voting 2 3 2 or 3 on the thermal sensation scale are dissatisfied and on the simplification that PPD is sym metric around a neutral PMV Table H1 defines the recommended PPD and PMV range for typical applications ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 10 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 The comfort zone is defined by the combinations of the six key factors for thermal comfort for which the PMV is within the recommended limits specified in Table H1 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 recom mended range the conditions are within the comfort zone Use of the PMV model in this standard is limited to air speeds below 020 ms 40 fpm When air speeds exceed 020 ms 40 fpm the comfort zone boundaries are adjusted based on the SET model described in the elevated airspeed section and in Normative Appendix D Several computer codes are available that predict PMVPPD The computer code in Normative Appen dix B was developed for use with this standard and is incorporated into the Thermal Comfort Tool3 If any other software is used it is the users responsibility to verify and document that the version used yields the same results as the code in Normative Appendix B or the Thermal Comfort Tool for the conditions for which it is applied H2 COMFORT ZONE BOUNDARIES The boundaries of the comfort zone are defined by equal contours of PMV values The boundary value is set at 05 PMV in thermal sensation scale units In field studies of actual buildings environmental conditions within comfort zones bounded by this 05 value were found satisfactory by roughly 80 of occupants This percentage varies depending on additional confounding circumstances beyond the PMV model of an occu pants heat balance Sources of local discomfort are thought to add to dissatisfaction as well as other factors such as occupants sense of personal control over their thermal environment This effect is described in Informative Appendix L Sections L1 L2 and L3 The measurement and evaluation methods for determin ing satisfaction are described in Sections 731 and 741 of the standard Comfort zones with the 05 PMV boundaries are generated by the Thermal Comfort Tool3 They are plotted in psychrometric chart format with air temperature ta or operative temperature to on the abscissa or in temperature vs relative humidity format In evaluating comfort zones it is usually most useful to use the operative temperature parameter as surface temperatures within indoor environments will shift along with air temperature across the width of the comfort zone The comfort zones are seen to shift continuously with changes to the environmental and personal input parameters that are not plotted on the two chart axes The presence of solar radiation on the occupant is shown to shift the comfort zone toward the cool side Elevating the air speed is shown to shift the comfort zone toward the warm side Note that there is an additional comfort attribute to elevated air speed that of whether occupants have control of it or not The presence or absence of group control over air speed pro Table H1 Acceptable Thermal Environment for General Comfort PPD PMV Range 10 05 PMV 05 Figure H1 Predicted percentage dissatisfied PPD as a function of predicted mean vote PMV tr ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 11 duces a subzoning as identified in Figure 54 This is also included in the output of the Thermal Comfort Tool3 Impacts of personal factors The outer comfort zone boundaries shift toward the left or right depending on clo and met level An increase of 01 clo or 01 met corresponds approximately to a 08C 14F or 05C 09F reduction in operative temperature to a decrease of 01 clo or 01 met corresponds approxi mately to a 08C 14F or 05C 09F increase in operative temperature The computer code in Normative Appendix B was developed for use with this standard and is incorpo rated into the Thermal Comfort Tool 3 If any other software is used it is the users responsibility to verify and document that the version used yields the same results as the code in Normative Appendix B or the Thermal Comfort Tool for the conditions for which it is applied H3 ELEVATED AIRSPEED COMFORT ZONE METHOD The outer boundary curves in Figure 54 shift toward the left or right depending on clo and met level An increase of 01 clo or 01 met corresponds approximately to a 08C 14F or 05C 09F reduction in operative temperature t0 a decrease of 01 clo or 01 met corresponds approximately to a 08C 14F or 05C 09F increase in operative temperature H43 HUMIDITY LIMITS TO THE COMFORT ZONE There are no established higher or lower humidity limits for thermal comfort consequently this standard does not specify a maximum or minimum humidity level Nonthermal comfort factors such as skin drying irritation of mucus membranes dryness of the eyes and static electricity generation may place limits on the acceptability ofsatisfaction with very low humidity environments Modify Informative Appendix I as shown The remainder of Informative Appendix I is unchanged I1 LOCAL THERMAL DISCOMFORT Avoiding local thermal discomfort whether caused by a vertical air temperature difference between the feet and the head by an asymmetric radiant field by local convective cooling draft or by contact with a hot or cold floor is essential to providing acceptable satisfactory thermal comfort The requirements specified in Section 533535 of this standard apply directly to a lightly clothed per son with clothing insulation between 05 and 07 clo engaged in nearsedentary physical activity with met abolic rates between 10 and 13 met With higher metabolic rates andor with more clothing insulation people are less thermally sensitive and consequently the risk of local discomfort is lower Thus it is accept able to use the requirements of Section 533535 for metabolic rates greater than 13 met and with clothing insulation greater than 07 clo as they will be conservative People are more sensitive to local discomfort when the whole body is cooler than neutral and less sensitive to local discomfort when the whole body is warmer than neutral The requirements of Section 533535 of this standard are based on environmental temperatures near the center of the comfort zone These requirements apply to the entire comfort zone but they may be conservative for conditions near the upper temperature limits of the comfort zone and may underestimate discomfort at the lower temperature limits of the comfort zone Table I1 shows the expected percent dissatisfied for each source of local thermal discomfort described in Sections 5335351 through 5335354 The criteria for all sources of local thermal discomfort should be met simultaneously at the levels specified for an environment to meet the require ments of Section 53 of this standard The expected percent dissatisfied for each source of local thermal dis comfort described in Sections 5335351 through 5335354 should be specified I2 RADIANT TEMPERATURE ASYMMETRY The thermal radiation field about the body may be nonuniform due to hot and cold surfaces and direct sun light This asymmetry may cause local discomfort and reduce the thermal acceptabilitysatisfaction withof the space In general people are more sensitive to asymmetric radiation caused by a warm ceiling than that caused by hot and cold vertical surfaces Figure I1 gives the expected percentage of occupants dissatisfied due to radiant temperature asymmetry caused by a warm ceiling a cool wall a cool ceiling or a warm wall I3 DRAFT Use of elevated air speed to extend the thermal comfort range is appropriate when otherwise occupants are slightly warm as set forth in Section 532534 When occupants are neutral or cooler such as under certain ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 12 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 combinations of met rate and clo value with operative temperatures to below 23C 734F average air speeds within the comfort envelope of 05 PMV should not exceed 020 ms 40 fpm This draft limit applies to air movement caused by the building its fenestration and its HVAC system and not to air move ment produced by office equipment or occupants This standard allows average air speed to exceed this draft limit if it is under the occupants local control and is within the elevated airspeed comfort envelope described in Section 532534 The air speed limits at 01 m 4 in in Section 5345363 are derived by setting PPDAD equal to 20 I4 VERTICAL AIR TEMPERATURE GRADIENT Thermal stratification that results in the air temperature at the head level being warmer than that at the ankle level may cause thermal discomfort Section 5335354 of this standard specifies allowable gradients of the air temperature between the head level and ankle level The vertical air temperature gradient limits in Section 5335354 are derived by setting equal to 5 I5 FLOOR SURFACE TEMPERATURE Occupants may feel uncomfortable due to contact with floor surfaces that are too warm or too cool The tem perature of the floor rather than the material of the floor covering is the most important factor for foot ther mal comfort while wearing shoes Figure I4 gives the percentage of occupants expected to be dissatisfied due to floor temperature tf based on people wearing lightweight indoor shoes Thus it is acceptable to use these criteria for people wearing heavier footgear as they will be conservative This standard does not address the floor temperature required for people not wearing shoes nor does it address acceptable satisfac tory floor temperatures for people sitting on the floor I7 CYCLIC VARIATIONS Cyclic variations refer to those situations where the operative temperature to repeatedly rises and falls and the period of these variations is not greater than 15 minutes If the period of the fluctuation cycle exceeds 15 minutes the variation is treated as a drift or ramp in operative temperature and the requirements of Section 5345362 apply In some situations variations with a period not greater than 15 minutes are superimposed on variations with a longer period In these situations the requirements of Section 5345361 apply to the component of the variation with a period not greater than 15 minutes and the requirements of Section 5345362 apply to the component of the variation with a period greater than 15 minutes I8 DRIFTS OR RAMPS Temperature drifts and ramps are monotonic noncyclic changes in operative temperature to The require ments of Section 5345362 also apply to cyclic variations with a period greater than 15 minutes Gener ally drifts refer to passive temperature changes of the enclosed space and ramps refer to actively controlled temperature changes Section 5345362 specifies the maximum change in operative temperature to allowed during a period of time For any given time period the most restrictive requirements from Table 511 apply For example the operative temperature may not change more than 22C 40F during a 10 hour period and it also may not change more than 11C 20F during any 025 hour period within that 10 hour period If the user cre ates variations as a result of control or adjustments higher values may be acceptable These local thermal comfort criteria were developed in order to keep the expected percent of occupants who are dissatisfied due to all of these local discomfort factors at or below 10 The operative temperature to ranges required in the standard were developed in order to keep the predicted percent dissatisfied of occu pants due to operative temperature only without factoring in local thermal factors When both local discom fort factors and operative temperature considerations are combined the goal of this standard to standardize satisfactory thermal conditions acceptable to or a substantial majority of occupants 80 is achieved This is especially true if there is some overlap between those who are dissatisfied due to local factors and those who are dissatisfied due to operative temperature PPD T ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 13 Modify Informative Appendix J as shown The remainder of Informative Appendix J is unchanged For spaces that meet these criteria it is acceptable to determine the allowable indoor operative tempera tures to from Figure 58 This figure includes two sets of operative temperature limits one for 80 accept ability satisfaction and one for 90 acceptabilitysatisfaction The 80 acceptability satisfaction limits are for typical applications It is acceptable to use the 90 acceptability satisfaction limits when a higher stan dard of thermal comfort is desired Figure 58 is based on an adaptive model of thermal comfort that is derived from a global database of 21000 measurements taken primarily in office buildings Figure 58 accounts for local thermal discomfort effects in typical buildings so it is not necessary to address these factors when using this option If there is reason to believe that local thermal comfort is a prob lem it is acceptable to apply the criteria in Section 533535 Figure 58 also accounts for peoples clothing adaptation in naturally conditioned spaces by relating the acceptable satisfactory range of indoor temperatures to the outdoor climate so it is not necessary to estimate the clothing values for the space No humidity or air speed limits are required when this option is used Figure 58 includes the effects of peoples indoor air speed adaptation in warm climates up to 03 ms 59 fpm in operative temperatures to warmer than 25C 77F In naturally conditioned spaces where air speeds within the occupied zone exceed 03 ms 59 fpm the upper acceptability satisfactory temperature limits in Figure 58 are increased by the corresponding t0 in Table 513 which is based on equal SET values as illus trated in Section 532534 For example increasing air speed within the occupied zone from 03 ms 59 fpm to 06 ms 118 fpm increases the upper acceptable satisfactory temperature limits in Figure 58 by a Δt0 of 12C 22F These adjustments to the upper satisfactoryacceptability temperature limits apply only at t0 25C 77F in which the occupants are engaged in near sedentary physical activity with metabolic rates between 10 met and 13 met Modify Informative Appendix L as shown The remainder of Informative Appendix L is unchanged a At any given PMV level a populations proportion of dissatisfied members may be predicted via the predicted percentage dissatisfied PPD curve This is an empirical profitprobit fit of thermal sensation TSENS survey scores obtained in a range of test environments in which dissatisfaction was assumed to occur at TSENS absolute values of 2 or greater With this method a PMV of 05 predicts 90 of a pop ulation satisfied or a 10 PPD L2 SURVEYING OCCUPANTS The use of occupant thermal environment surveys is an acceptable way of assessing comfort conditions for the acceptability satisfaction ranges discussed in this standard With surveys one may mea sure the percent who are satisfied acceptable or comfortable by putting those direct questions to a representative sample of the occupants L21 Pointintime rightnow surveys are used to evaluate thermal sensations of occupants occupants thermal experience at a single point in time Thermal comfort researchers have used these surveys to cor relate thermal comfort with environmental factors such as those included in the PMV model metabolic rate clothing insulation air temperature radiant temperature air speed and humidity A sample pointintime survey is included in Figure L1 This isIt includes a thermal sensation survey that asks occupants to rate their sensation from hot to cold on the ASHRAE sevenpoint thermal sen sation scale The scale units are sometimes designated TSENS One may however ask It also asks the direct question Is the environment thermally acceptable How satisfied are you with the thermal environment with a scale of very unacceptable dissatisfied to very acceptable satisfied The satisfaction scale is a standard psychometric test in other disciplines and is best divided into seven scale units or more Preference scales for temperature and air movement are sometimes used in field studies These are pres ent in both the ASHRAE Global Thermal Comfort Database II and ASHRAE RP884 Towards an Adaptive Model of Thermal Comfort and Preference A three point scale with cooler without change warmer for thermal preference and less air movement no change more air movement for air movement preference is advised Optional scales are provided for reference ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 14 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 In order to use the results of a pointintime survey to assess comfort acceptability ranges satisfaction with the thermal environment over time the survey would have to be implemented under multiple thermal conditions and in multiple building operating modes The difficulty of arranging multiple surveys in work place environments usually limits the feasibility of using the pointintime survey approach for assessing comfort over time This limitation may diminish with the advent use of webbased and mobile applications oriented toward building operation L22 An example thermal satisfaction survey is included in Figure L2 It asks occupants to rate their satisfac tion with their thermal environment from very satisfied to very dissatisfied on a sevenpoint satisfac tion scale The percentage of occupants satisfied shall be calculated from sevenpoint satisfaction survey scores by dividing the number of votes falling between 1 and 3 inclusive by the total number of votes The percentage of occupants dissatisfied shall be calculated from sevenpoint satisfaction survey scores by dividing the number of votes falling between 1 and 3 inclusive by the total number of votes Acceptabil ity is determined in two ways by the percentage of occupants who have responded neutral through very satisfied 0 1 2 or 3 with their environment or by taking a slightly broader view of acceptability including the percentage who have responded 1 0 1 2 3 The basic premise of the satisfaction survey is that occupants by nature can recall instances or periods of thermal discomfort identify patterns in building operation and provide overall or average comfort votes on their environment The surveyor may identify a span of time for the respondents to consider The occupants provide the time integration Questions to identify the nature causes of dissatisfaction may be included in satisfaction surveys eg questions 7a through 7e in Figure L2 Because the survey results encompass a larger time frame the survey can be administered every six months or repeated in heating andor cooling seasons In a new building the first thermal satisfaction survey may be performed approximately six months after occupancy late enough to avoid assessing the effects of putting the building into commission but early enough to help identify and solve longterm building prob lems that have escaped detection in the commissioning process The premise of the satisfaction survey is that occupants can recall instances or periods of thermal dis comfort identify patterns in building operation and provide overall or average comfort votes on their environment The surveyor may identify a span of time for the respondents to consider and the occupants provide the time integration Questions to identify the nature causes of dissatisfaction may be included in satisfaction surveys eg sourceofdiscomfort questions in Figure L2 As the thermal satisfaction survey assesses a long time frame it should be administered every six months or repeated in heating andor cooling seasons In a new building the first thermal satisfaction survey may be performed approximately six months after occupancy late enough to avoid assessing the effects of building commissioning but early enough to help identify longterm building problems that have escaped detection in the commissioning process The thermal satisfaction survey can be used by researchers building operators and facility managers to assess assessments of building systems performance and operation in new buildings and to perform in addition to periodic postoccupancy postoccupancy evaluation in existing facilities ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 15 Delete current Figures L1 and L2 not shown and replace with the following Figure L1 Thermal environment pointintime survey Note For all surveys remove the numerical values under the scales before presenting the survey to occupants They are used to code responses and analyze results in a standard manner ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 16 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 Figure L1 continued Thermal environment pointintime survey ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 17 Figure L2 Thermal environment satisfaction survey ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission 18 ANSIASHRAE Addendum h to ANSIASHRAE Standard 552020 Figure L2 continued Thermal environment satisfaction survey ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission POLICY STATEMENT DEFINING ASHRAES CONCERN FOR THE ENVIRONMENTAL IMPACT OF ITS ACTIVITIES ASHRAE is concerned with the impact of its members activities on both the indoor and outdoor environment ASHRAEs members will strive to minimize any possible deleterious effect on the indoor and outdoor environment of the systems and components in their responsibility while maximizing the beneficial effects these systems provide consistent with accepted Standards and the practical state of the art ASHRAEs shortrange goal is to ensure that the systems and components within its scope do not impact the indoor and outdoor environment to a greater extent than specified by the Standards and Guidelines as established by itself and other responsible bodies As an ongoing goal ASHRAE will through its Standards Committee and extensive Technical Committee structure continue to generate uptodate Standards and Guidelines where appropriate and adopt recommend and promote those new and revised Standards developed by other responsible organizations Through its Handbook appropriate chapters will contain uptodate Standards and design considerations as the material is systematically revised ASHRAE will take the lead with respect to dissemination of environmental information of its primary interest and will seek out and disseminate information from other responsible organizations that is pertinent as guides to updating Standards and Guidelines The effects of the design and selection of equipment and systems will be considered within the scope of the systems intended use and expected misuse The disposal of hazardous materials if any will also be considered ASHRAEs primary concern for environmental impact will be at the site where equipment within ASHRAEs scope operates However energy source selection and the possible environmental impact due to the energy source and energy transportation will be considered where possible Recommendations concerning energy source selection should be made by its members ASHRAE Per international copyright law additional reproduction distribution or transmission in either print or digital form is not permitted without ASHRAEs prior written permission ASHRAE 180 Technology Parkway Peachtree Corners GA 30092 wwwashraeorg About ASHRAE Founded in 1894 ASHRAE is a global professional society committed to serve humanity by advancing the arts and sciences of heating ventilation air conditioning refrigeration and their allied fields As an industry leader in research standards writing publishing certification and continuing education ASHRAE and its members are dedicated to promoting a healthy and sustainable built environment for all through strategic partnerships with organizations in the HVACR community and across related industries To stay current with this and other ASHRAE Standards and Guidelines visit wwwashraeorgstandards and connect on LinkedIn Facebook Twitter and YouTube Visit the ASHRAE Bookstore ASHRAE offers its Standards and Guidelines in print as immediately downloadable PDFs and via ASHRAE Digital Collections which provides online access with automatic updates as well as historical versions of publications Selected Standards and Guidelines are also offered in redline versions that indicate the changes made between the active Standard or Guideline and its previous version For more information visit the Standards and Guidelines section of the ASHRAE Bookstore at wwwashraeorgbookstore IMPORTANT NOTICES ABOUT THIS STANDARD To 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