Introduction to thermal comfort standards and to the proposed new version of EN ISO 7730

Outline Introduction How is an ISO standard produced? ISO 9920 ergonomics of the thermal General thermal comfort Local thermal discomfort Discussion and conclusion

Introduction The International Standards Organization (ISO) was set up in 1947 and has over 130 member countries The aim of this paper is to provide an introduction to ISO standards concerned with thermal comfort and to describe the proposed revision of thermal comfort standard EN ISO 7730

How is an ISO standard produced Table 1 Six-stage process to the production of an International Standard (ISO) Six-stage process to the production of an International Standard (ISO)

How is an ISO standard produced? ISO standards are produced by experts from participating countries according to agreed rules and a system of voting A thermal comfort standard is proposed and supported by a document that explains the requirement

How is an ISO standard produced? The Committee Draft (ISO CD 7730) is circulated to member countries who will circulate it within their country and provide comments and a vote The WG will respond to comments and revise the document accordingly A Draft International Standard (ISO DIS 7730) will then be produced

ISO 7730 The PMV predicts the mean value of the votes of a large group of people on the ISO thermal sensation scale (+3=hot;+2=warm;+1=slightly warm; 0=neutral;- 1=slightly cool; -2=cool; -3=cold)

ISO 7730: validity Related to the validity of ISO 7730 is the validity of ISO 8996-metabolic rate and ISO 9920-clothing The estimation of metabolic heat production and clothing insulation and other properties are difficult especially when considering practical dynamic contexts

ISO 7730: scope The standard notes that deviations may occur due to ethnic and national geographic deviations and for people who are sick or disabled.It applies to healthy men and women Children are not considered

ISO 9920 ergonomics of the thermal Environment estimation of the thermal insulation and evaporative resistance of a clothing ensemble ISO 9920 provides an extensive database of the thermal properties of clothing and garments

ISO 9920 ergonomics of the thermal Table 2 The influence of accuracy of estimate of metabolic rate and clothing insulation on PMV and PPD values

ISO 9920 ergonomics of the thermal Table 3 Three categories of thermal environment: percentage of dissatisfied due to general comfort and local discomfort

General thermal comfort Separate comfort zones for two seasons reflect the fact that people usually change clothing according to outside temperature

General thermal comfort Table 4 Example criteria for operative temperature and mean air velocity for typical spaces

General thermal comfort Fig.1 Air speed required to offset increased temperature.

General thermal comfort Fig.2 Comparison of the RP-884 adaptive models predicted indoor comfort temperatures with those predicted by the PMV- model for both air-conditioned and naturally ventilated buildings

Local thermal discomfort Local thermal discomfort may be caused by draught ， high vertical temperature difference between head and ankles Too warm or too cool a floor ， or by too high a radiant temperature asymmetry Persons engaged in light sedentary activity are the most sensitive to local discomfort

Local thermal discomfort Fig.3 Mean air velocity as a function of local air temperature and turbulence intensity for the three categories of the thermal environment

Local thermal discomfort Fig.4 Local discomfort caused by vertical air temperature difference.

Local thermal discomfort Fig.5 Local thermal discomfort caused by warm or cold floors.

Local thermal discomfort Fig.6 Local thermal discomfort caused by radiant temperature asymmetry

Discussion and conclusion Some important issues are being discussed in the current round of standard revisions. Fulfilling the given criteria does not guarantee 100% thermal acceptability

Discussion and conclusion the local thermal discomfort parameters like vertical air temperature differences ， floor surface temperatures and radiant temperature asymmetry have mainly been studied for younger ， sedentary people in general thermal comfort

Discussion and conclusion Standards governing indoor thermal environments at the international level (International Standard Organization (ISO);European Standard Organization (CEN)) ， and also the national level (ASHRAE) are on a constant cycle of revision ， public review,and promulgation

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