EN ISO 7730:2005

SLOVENSKI STANDARD
01-marec-2006
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SIST EN ISO 7730:2001
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Ergonomics of the thermal environment - Analytical determination and interpretation of
thermal comfort using calculation of the PMV and PPD indices and local thermal comfort
criteria (ISO 7730:2005)
Ergonomie der thermischen Umgebung - Analytische Bestimmung und Interpretation der
thermischen Behaglichkeit durch Berechnung des PMV- und des PPD-Indexes und
Kriterien der lokalen thermischen Behaglichkeit (ISO 7730:2005)
Ergonomie des ambiances thermiques - Détermination analytique et interprétation du
confort thermique par le calcul des indices PMV et PPD et par des criteres de confort
thermique local (ISO 7730:2005)
Ta slovenski standard je istoveten z: EN ISO 7730:2005
ICS:
13.180 Ergonomija Ergonomics
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EUROPEAN STANDARD
EN ISO 7730
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2005
ICS 13.180 Supersedes EN ISO 7730:1995
English Version
Ergonomics of the thermal environment - Analytical
determination and interpretation of thermal comfort using
calculation of the PMV and PPD indices and local thermal
comfort criteria (ISO 7730:2005)
Ergonomie des ambiances thermiques - Détermination Ergonomie der thermischen Umgebung - Analytische
analytique et interprétation du confort thermique par le Bestimmung und Interpretation der thermischen
calcul des indices PMV et PPD et par des critères de Behaglichkeit durch Berechnung des PMV- und des PPD-
confort thermique local (ISO 7730:2005) Indexes und Kriterien der lokalen thermischen
Behaglichkeit (ISO 7730:2005)
This European Standard was approved by CEN on 21 October 2005.
CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European
Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national
standards may be obtained on application to the Central Secretariat or to any CEN member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by translation
under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official
versions.
CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.
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© 2005 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 7730:2005: E
worldwide for CEN national Members.

Foreword
This document (EN ISO 7730:2005) has been prepared by Technical Committee ISO/TC 159
"Ergonomics" in collaboration with Technical Committee CEN/TC 122 "Ergonomics", the
secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of
an identical text or by endorsement, at the latest by May 2006, and conflicting national standards
shall be withdrawn at the latest by May 2006.

This document supersedes EN ISO 7730:1995.

According to the CEN/CENELEC Internal Regulations, the national standards organizations of
the following countries are bound to implement this European Standard: Austria, Belgium,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary,
Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland,
Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Endorsement notice
The text of ISO 7730:2005 has been approved by CEN as EN ISO 7730:2005 without any
modifications.
INTERNATIONAL ISO
STANDARD 7730
Third edition
2005-11-15
Ergonomics of the thermal
environment — Analytical determination
and interpretation of thermal comfort
using calculation of the PMV and PPD
indices and local thermal comfort criteria
Ergonomie des ambiances thermiques — Détermination analytique et
interprétation du confort thermique par le calcul des indices PMV et
PPD et par des critères de confort thermique local

Reference number
ISO 7730:2005(E)
©
ISO 2005
ISO 7730:2005(E)
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ii © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Contents Page
Foreword. iv
Introduction . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions. 1
4 Predicted mean vote (PMV) . 2
5 Predicted percentage dissatisfied (PPD). 4
6 Local thermal discomfort. 6
7 Acceptable thermal environments for comfort. 10
8 Non-steady-state thermal environments. 11
9 Long-term evaluation of the general thermal comfort conditions. 11
10 Adaptation . 12
Annex A (informative) Examples of thermal comfort requirements for different categories of
environment and types of space. 13
Annex B (informative) Metabolic rates of different activities. 18
Annex C (informative) Estimation of thermal insulation of clothing ensembles. 19
Annex D (normative) Computer program for calculating PMV and PPD. 23
Annex E (normative) Tables for determination of predicted mean vote (PMV) . 26
Annex F (informative) Humidity . 44
Annex G (informative) Air velocity. 45
Annex H (informative) Long-term evaluation of the general thermal comfort conditions. 47
Bibliography . 49

ISO 7730:2005(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
(ISO member bodies). The work of preparing International Standards is normally carried out through ISO
technical committees. Each member body interested in a subject for which a technical committee has been
established has the right to be represented on that committee. International organizations, governmental and
non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the
International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. ISO shall not be held responsible for identifying any or all such patent rights.
ISO 7730 was prepared by Technical Committee ISO/TC 159, Ergonomics, Subcommittee SC 5, Ergonomics
of the physical environment.
This third edition cancels and replaces the second edition (ISO 7730:1994), which has been technically
revised. A method for long term evaluation has been added, as well as information on local thermal discomfort,
non-steady-state conditions and adaptation, and an annex stating how thermal comfort requirements can be
expressed in different categories.
iv © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Introduction
This International Standard covering the evaluation of moderate thermal environments was developed in
1)
parallel with the revised ASHRAE standard 55 and is one of a series of ISO documents specifying methods
for the measurement and evaluation of the moderate and extreme thermal environments to which human
beings are exposed (ISO 7243, ISO 7933 and ISO/TR 11079, all three dealing with extreme environmental
conditions, are others in the series).
A human being's thermal sensation is mainly related to the thermal balance of his or her body as a whole.
This balance is influenced by physical activity and clothing, as well as the environmental parameters: air
temperature, mean radiant temperature, air velocity and air humidity. When these factors have been
estimated or measured, the thermal sensation for the body as a whole can be predicted by calculating the
predicted mean vote (PMV). See Clause 4.
The predicted percentage dissatisfied (PPD) index provides information on thermal discomfort or thermal
dissatisfaction by predicting the percentage of people likely to feel too warm or too cool in a given environment.
The PPD can be obtained from the PMV. See Clause 5.
Thermal discomfort can also be caused by unwanted local cooling or heating of the body. The most common
local discomfort factors are radiant temperature asymmetry (cold or warm surfaces), draught (defined as a
local cooling of the body caused by air movement), vertical air temperature difference, and cold or warm floors.
Clause 6 specifies how to predict the percentage dissatisfied owing to local discomfort parameters.
Dissatisfaction can be caused by hot or cold discomfort for the body as a whole. Comfort limits can in this
case be expressed by the PMV and PPD indices. But thermal dissatisfaction can also be caused by local
thermal discomfort parameters. Clause 7 deals with acceptable thermal environments for comfort.
Clauses 6 and 7 are based mainly on steady-state conditions. Means of evaluating non-steady-state
conditions such as transients (temperature steps), cycling temperatures or temperature ramps are presented
in Clause 8. The thermal environments in buildings or at workplaces will change over time and it might not
always be possible to keep conditions within recommended limits. A method for long-term evaluation of
thermal comfort is given in Clause 9.
Clause 10 gives recommendations on how to take into account the adaptation of people when evaluating and
designing buildings and systems.

1) American Society of Heating, Refrigerating and Air-conditioning Engineers.
INTERNATIONAL STANDARD ISO 7730:2005(E)

Ergonomics of the thermal environment — Analytical
determination and interpretation of thermal comfort using
calculation of the PMV and PPD indices and local thermal
comfort criteria
1 Scope
This International Standard presents methods for predicting the general thermal sensation and degree of
discomfort (thermal dissatisfaction) of people exposed to moderate thermal environments. It enables the
analytical determination and interpretation of thermal comfort using calculation of PMV (predicted mean vote)
and PPD (predicted percentage of dissatisfied) and local thermal comfort criteria, giving the environmental
conditions considered acceptable for general thermal comfort as well as those representing local discomfort. It
is applicable to healthy men and women exposed to indoor environments where thermal comfort is desirable,
but where moderate deviations from thermal comfort occur, in the design of new environments or the
assessment of existing ones. Although developed specifically for the work environment, it is applicable to
other kinds of environment as well. It is intended to be used with reference to ISO/TS 14415:2005, 4.2, when
considering persons with special requirements, such as those with physical disabilities. Ethnic, national or
geographical differences need also to be taken into account when considering non-conditioned spaces.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 13731, Ergonomics of the thermal environment — Vocabulary and symbols
ISO/TS 13732-2, Ergonomics of the thermal environment — Methods for the assessment of human responses
to contact with surfaces — Part 2: Human contact with surfaces at moderate temperature
ISO/TS 14415:2005, Ergonomics of the thermal environment — Application of International Standards to
people with special requirements
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 13731 and the following apply.
3.1
temperature cycle
variable temperature with a given amplitude and frequency
3.2
drift temperature
passive monotonic, steady, non-cyclic change in the operative temperature of an enclosed space
ISO 7730:2005(E)
3.3
ramp temperature
actively controlled monotonic, steady, non-cyclic change in the operative temperature of an enclosed space
3.4
operative temperature
t
o
uniform temperature of an imaginary black enclosure in which an occupant would exchange the same amount
of heat by radiation and convection as in the actual non-uniform environment
3.5
transient temperature
sudden change in the thermal conditions due to step change in temperature, humidity, activity or clothing
3.6
draught
unwanted local cooling of the body caused by air movement
4 Predicted mean vote (PMV)
4.1 Determination
The PMV is an index that predicts the mean value of the votes of a large group of persons on the 7-point
thermal sensation scale (see Table 1), based on the heat balance of the human body. Thermal balance is
obtained when the internal heat production in the body is equal to the loss of heat to the environment. In a
moderate environment, the human thermoregulatory system will automatically attempt to modify skin
temperature and sweat secretion to maintain heat balance.
Table 1 — Seven-point thermal sensation scale
+ 3 Hot
+ 2 Warm
+ 1 Slightly warm
0 Neutral
− 1 Slightly cool
−2 Cool
− 3 Cold
2 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Calculate the PMV using Equations (1) to (4):
PMV=⋅0,303 exp(−0,036⋅M )+ 0,028⋅
⎡⎤
⎣⎦
⎧ ⎫
−3
⎡ ⎤⎡ ⎤
MW−− 3,05⋅10⋅ 5 733− 6,99⋅M−−W p− 0,42⋅ M−−W 58,15
() () ()
⎪ a ⎪
⎣ ⎦⎣ ⎦
⎪ ⎪
⎪ ⎪
−5
−1,7⋅10 ⋅⋅Mp5 867− − 0,0014⋅⋅M 34−t (1)
() ( )
⎨ ⎬
aa
⎪ ⎪
−8
⎡⎤
⎪ ⎪
−⋅3,96 10⋅ft⋅()+ 273−()t+ 273 −f⋅h⋅(t−t)
cl cl r cl c cl a
⎢⎥
⎪ ⎪
⎣⎦
⎩ ⎭
−8⎡⎤
tM=−35,7 0,028⋅ −W−I⋅ 3,96⋅10⋅f⋅t+ 273−t+ 273+f⋅h⋅t−t (2)
() ()() ( )
cl cl cl cl r cl c cl a
{}
⎢⎥
⎣⎦
0,25 0,25
⎧
2,38⋅−tt for 2,38⋅−tt > 12,1⋅v
cl a cl a ar
⎪
h = (3)
⎨
c
0,25
⎪
12,1⋅⋅vtfor 2,38−t<12,1⋅v
ar cl a ar
⎩
⎧
1,00+⋅1,290llfor u 0,078 m K/W
⎪ cl cl
f = (4)
⎨
cl
1,05+>0,645llfor 0,078 m⋅K/W
⎪
⎩ cl cl
where
M is the metabolic rate, in watts per square metre (W/m );
W is the effective mechanical power, in watts per square metre (W/m );
I is the clothing insulation, in square metres kelvin per watt (m ⋅ K/W);
cl
f is the clothing surface area factor;
cl
t is the air temperature, in degrees Celsius (°C);
a
t is the mean radiant temperature, in degrees Celsius (°C);
r
v is the relative air velocity, in metres per second (m/s);
ar
p is the water vapour partial pressure, in pascals (Pa);
a
h is the convective heat transfer coefficient, in watts per square metre kelvin [W/(m ⋅ K)];
c
t is the clothing surface temperature, in degrees Celsius (°C).
cl
2 2
NOTE 1 metabolic unit = 1 met = 58,2 W/m ; 1 clothing unit = 1 clo = 0,155 m ⋅ °C/W.
PMV may be calculated for different combinations of metabolic rate, clothing insulation, air temperature, mean
radiant temperature, air velocity and air humidity (see ISO 7726). The equations for t and h may be solved
cl c
by iteration.
The PMV index is derived for steady-state conditions but can be applied with good approximation during minor
fluctuations of one or more of the variables, provided that time-weighted averages of the variables during the
previous 1 h period are applied.
The index should be used only for values of PMV between −2 and +2, and when the six main parameters are
within the following intervals:
2 2
M 46 W/m to 232 W/m (0,8 met to 4 met);
ISO 7730:2005(E)
2 2
I 0 m ⋅ K/W to 0,310 m ⋅ K/W (0 clo to 2 clo);
cl
t 10 °C to 30 °C;
a
t 10 °C to 40 °C;
r
v 0 m/s to 1 m/s;
ar
p 0 Pa to 2 700 Pa.
a
NOTE In respect of v , during light, mainly sedentary, activity, a mean velocity within this range can be felt as a
ar
draught.
Estimate the metabolic rate using ISO 8996 or Annex B, taking into account the type of work. For varying
metabolic rates, a time-weighted average should be estimated during the previous 1 h period. Estimate the
thermal resistance of clothing and chair using ISO 9920 or Annex C, taking into account the time of year.
Determine the PMV in one of the following ways.
a) From Equation (1) using a digital computer. A BASIC program is given in Annex D for this purpose. For
verification of other computer programs, Annex D provides example output.
b) Directly from Annex E, where tables of PMV values are given for different combinations of activity,
clothing, operative temperature and relative velocity.
c) By direct measurement, using an integrating sensor (equivalent and operative temperatures).
The PMV values given in Annex E apply for a relative humidity of 50 %. The influence of humidity on thermal
sensation is small at moderate temperatures close to comfort and may usually be disregarded when
determining the PMV value (see Annex F).
4.2 Applications
The PMV can be used to check whether a given thermal environment complies with comfort criteria (see
Clause 7 and Annex A), and to establish requirements for different levels of acceptability.
By setting PMV = 0, an equation is established which predicts combinations of activity, clothing and
environmental parameters which on average will provide a thermally neutral sensation.
5 Predicted percentage dissatisfied (PPD)
The PMV predicts the mean value of the thermal votes of a large group of people exposed to the same
environment. But individual votes are scattered around this mean value and it is useful to be able to predict
the number of people likely to feel uncomfortably warm or cool.
The PPD is an index that establishes a quantitative prediction of the percentage of thermally dissatisfied
people who feel too cool or too warm. For the purposes of this International Standard, thermally dissatisfied
people are those who will vote hot, warm, cool or cold on the 7-point thermal sensation scale given in Table 1.
With the PMV value determined, calculate the PPD using Equation (5), see Figure 1:
PPD=−100 95⋅ exp(−0,033 53⋅PMV− 0,217 9⋅PMV ) (5)
4 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Key
PMV predicted mean vote
PPD predicted percentage dissatisfied, %
Figure 1 — PPD as function of PMV
The PPD predicts the number of thermally dissatisfied persons among a large group of people. The rest of the
group will feel thermally neutral, slightly warm or slightly cool. The predicted distribution of votes is given in
Table 2.
Table 2 — Distribution of individual thermal sensation votes for different values of mean vote
a
PMV PPD Persons predicted to vote
%
0 −1, 0 or +1 −2, −1, 0, +1 or +2
+2 75 5 25 70
+1 25 30 75 95
+0,5 10 55 90 98
0 5 60 95 100
−0,5 10 55 90 98
−1 25 30 75 95
−2 75 5 25 70
a
Based on experiments involving 1 300 subjects.
ISO 7730:2005(E)
6 Local thermal discomfort
6.1 General
The PMV and PPD express warm and cold discomfort for the body as a whole. But thermal dissatisfaction can
also be caused by unwanted cooling or heating of one particular part of the body. This is known as local
discomfort. The most common cause of local discomfort is draught (6.2). But local discomfort can also be
caused by an abnormally high vertical temperature difference between the head and ankles (6.3), by too warm
or too cool a floor (6.4), or by too high a radiant temperature asymmetry (6.5). Annex A provides examples of
local and overall thermal comfort requirements for different categories of environment and types of space.
It is mainly people at light sedentary activity who are sensitive to local discomfort. These will have a thermal
sensation for the whole body close to neutral. At higher levels of activity, people are less thermally sensitive
and consequently the risk of local discomfort is lower.
6.2 Draught
The discomfort due to draught may be expressed as the percentage of people predicted to be bothered by
draught. Calculate the draught rate (DR) using Equation (6) (model of draught):
0,62
DR=−34 t v− 0,05 0,37⋅v⋅Tu+ 3,14 (6)
() a,l a,l
()()
a,l
For v < 0,05 m/s: use v = 0,05 m/s
a,l a,l
For DR > 100 %: use DR = 100 %
where
t is the local air temperature, in degrees Celsius, 20 °C to 26 °C;
a,l
v is the local mean air velocity, in metres per second, < 0,5 m/s;
a,l
Tu is the local turbulence intensity, in percent, 10 % to 60 % (if unknown, 40 % may be used).
The model applies to people at light, mainly sedentary activity with a thermal sensation for the whole body
close to neutral and for prediction of draught at the neck. At the level of arms and feet, the model could
overestimate the predicted draught rate. The sensation of draught is lower at activities higher than sedentary
(> 1,2 met) and for people feeling warmer than neutral. Additional information on the effect of air velocity can
be found in Annex G.
6.3 Vertical air temperature difference
A high vertical air temperature difference between head and ankles can cause discomfort. Figure 2 shows the
percentage dissatisfied (PD) as a function of the vertical air temperature difference between head and ankles.
The figure applies when the temperature increases upwards. People are less sensitive under decreasing
temperatures. Determine the PD using Equation (7):
(7)
PD=
1+−exp(5,76 0,856⋅∆t )
a,v
Equation (7), derived from the original data using logistic regression analysis, should only be used at
∆t < 8 °C.
a,v
6 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Key
PD percentage dissatisfied, %
∆t vertical air temperature difference between head and feet, °C
a,v
Figure 2 — Local discomfort caused by vertical air temperature difference
ISO 7730:2005(E)
6.4 Warm and cool floors
If the floor is too warm or too cool, the occupants could feel uncomfortable owing to thermal sensation of their
feet. For people wearing light indoor shoes, it is the temperature of the floor rather than the material of the
floor covering which is important for comfort. Figure 3 shows the percentage dissatisfied as a function of the
floor temperature, based on studies with standing and/or sedentary people.

Key
PD percentage dissatisfied, %
t floor temperature, °C
f
Figure 3 — Local thermal discomfort caused by warm or cold floors
For people sitting or lying on the floor, similar values may be used. Determine the PD using Equation (8),
derived from the original data using non-linear regression analysis:
PD=−100 94⋅ exp(−1,387+ 0,118⋅t− 0,002 5⋅t ) (8)
ff
For longer occupancy the results are not valid for electrically heated floors.
NOTE By electrical heating, a certain heat input is provided independent of the surface temperature. A water-based
heating system will not produce temperatures higher than the water temperature.
For spaces that people occupy with bare feet, see ISO/TS 13732-2.
8 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
6.5 Radiant asymmetry
Radiant asymmetry (∆t ) can also cause discomfort. People are most sensitive to radiant asymmetry caused
pr
by warm ceilings or cool walls (windows). Figure 4 shows the percentage dissatisfied as a function of the
radiant temperature asymmetry caused by a warm ceiling, a cool wall, a cool ceiling or by a warm wall. For
horizontal radiant asymmetry, Figure 4 applies from side-to-side (left/right or right/left) asymmetry, the curves
providing a conservative estimate of the discomfort: no other positions of the body in relation to the surfaces
(e.g. front/back) cause higher asymmetry discomfort. Determine the PD using Equations (9) to (12), as
applicable.
a) Warm ceiling
PD=− 5,5 (9)
1+−exp(2,84 0,174⋅∆t )
pr
∆t < 23 °C
pr
b) Cool wall
PD= (10)
1+−exp(6,61 0,345⋅∆t )
pr
∆t < 15 °C
pr
c) Cool ceiling
PD= (11)
1e+−xp(9,93 0,50⋅∆t )
pr
∆t < 15 °C
pr
d) Warm wall
PD=− 3,5 (12)
1+−exp(3,72 0,052⋅∆t )
pr
∆t < 35 °C
pr
Equations (9) to (12) were derived from the original data using logistic regression analysis, and should not be
used beyond the ranges shown above. Those for a) (warm ceiling) and for d) (warm wall) have been adjusted
to account for discomfort not caused by radiant asymmetry. See Figure 4.
ISO 7730:2005(E)
Key
PD percentage dissatisfied, %
∆t radiant temperature asymmetry, °C
pr
1 Warm ceiling.
2 Cool wall.
3 Cool ceiling.
4 Warm wall.
Figure 4 — Local thermal discomfort caused by radiant temperature asymmetry
7 Acceptable thermal environments for comfort
Thermal comfort is that condition of mind which expresses satisfaction with the thermal environment.
Dissatisfaction can be caused by warm or cool discomfort of the body as a whole, as expressed by the PMV
and PPD, or by an unwanted cooling (or heating) of one particular part of the body.
Due to individual differences, it is impossible to specify a thermal environment that will satisfy everybody.
There will always be a percentage dissatisfied occupants. But it is possible to specify environments predicted
to be acceptable by a certain percentage of the occupants.
Often it will be the same persons who are sensitive to different types of local discomfort. For instance, a
person sensitive to draught may also be sensitive to local cooling caused by radiant asymmetry or by a cold
floor. Such a cold-sensitive person may also more easily experience cool discomfort for the body as a whole.
Therefore, the PPD, DR or PD caused by other types of local discomfort should not be added.
Due to local or national priorities, technical developments and climatic regions, a higher thermal quality (fewer
dissatisfied) or lower quality (more dissatisfied) in some cases may be accepted. In such cases, the PMV and
PPD, the model of draught, the relation between local thermal discomfort parameters (see Clause 6), and the
expected percentage of dissatisfied people may be used to determine different ranges of environmental
parameters for the evaluation and design of the thermal environment.
Examples of different categories of requirements are given in Annex A.
10 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
8 Non-steady-state thermal environments
8.1 General
The basis for the methods given in the preceding clauses is steady-state conditions. The thermal environment
is, however, often in a non-steady-state and the question arises as to whether the methods then apply. Three
types of non-steady-state conditions can occur: temperature cycles, temperature drifts or ramps, and
transients.
8.2 Temperature cycles
Temperature cycles can occur due to the control of the temperature in a space. If the peak-to-peak variation is
less than 1 K, there will be no influence on the comfort and the recommendations for steady-state may be
used. Higher peak variations can decrease comfort.
8.3 Temperature drifts or ramps
If the rate of temperature change for drifts or ramps is lower than 2,0 K/h, the methods for steady-state
variation apply.
8.4 Transients
In general, the following statements regarding transients can be made.
⎯ A step-change of operative temperature is felt instantaneously.
⎯ After an up-step in operative temperature, the new steady-state thermal sensation is experienced
immediately, i.e. the PMV-PPD can be used to predict comfort.
⎯ Following a down-step in operative temperature, the thermal sensation drops at first to a level beneath
the one predicted by PMV, then increases and reaches under steady-state conditions the steady-state
level after approximately 30 min, i.e. the PMV-PPD predicts values that are too high for the first 30 min.
The time to reach a new steady-state condition depends on the initial conditions.
9 Long-term evaluation of the general thermal comfort conditions
Different categories of general comfort may be specified as ranges for the PMV-PPD (see Annex A).
If these criteria are to be met, including extreme situations, the heating- and/or cooling capacity of any HVAC
(heating, ventilation, air-conditioning) installation should be relatively high. Economic and/or environmental
considerations can lead to acceptable limited time intervals during which the PMV will be allowed to stay
outside the specified ranges.
By computer simulation or measurements, comfort conditions are often tested during longer periods for
different types of building and/or HVAC design. The need here is to specify a characteristic value for the long-
term comfort conditions for comparison of designs and performances.
For this purpose, a non-exhaustive list of methods that could be applied is presented in Annex H.
ISO 7730:2005(E)
10 Adaptation
In determining the acceptable range of operative temperature according to this International Standard, a
clothing insulation value that corresponds to the local clothing habits and climate shall be used.
In warm or cold environments, there can often be an influence due to adaptation. Apart from clothing, other
forms of adaptation, such as body posture and decreased activity, which are difficult to quantify, can result in
the acceptance of higher indoor temperatures. People used to working and living in warm climates can more
easily accept and maintain a higher work performance in hot environments than those living in colder climates
(see ISO 7933 and ISO 7243).
Extended acceptable environments may be applied for occupant-controlled, naturally conditioned, spaces in
warm climate regions or during warm periods, where the thermal conditions of the space are regulated
primarily by the occupants through the opening and closing of windows. Field experiments have shown that
occupants of such buildings could accept higher temperatures than those predicted by the PMV. In such
cases, the thermal conditions may be designed for higher PMV values than those given in Clause 6 and
Annex A.
12 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Annex A
(informative)
Examples of thermal comfort requirements for different categories
of environment and types of space
A.1 Categories of thermal environment
The desired thermal environment for a space may be selected from among the three categories, A, B and C
according to Table A.1. All the criteria should be satisfied simultaneously for each category.
Table A.1 — Categories of thermal environment
Thermal state of the body as a whole Local discomfort
PPD PMV DR PD
% % %
Category
caused by
vertical air warm or cool radiant
temperature floor asymmetry
difference
A < 6 − 0,2 < PMV < + 0,2 < 10 < 3 < 10 < 5
B < 10 − 0,5 < PMV < + 0,5 < 20 < 5 < 10 < 5
C < 15 − 0,7 < PMV < + 0,7 < 30 < 10 < 15 < 10
Each category prescribes a maximum percentage dissatisfied for the body as a whole (PPD) and a PD for
each of the four types of local discomfort. Some requirements are difficult to meet in practice while others are
quite easily met. The different percentages express a balance struck between the aim of a few dissatisfied
and what is practically obtainable using existing technology.
Owing to the accuracy of instrumentation for measuring the input parameters, it can be difficult to verify that
the PMV conforms to the Class A category (−0,2 < PMV < +0,2). Instead, the verification may be based on the
equivalent operative temperature range, as specified in A.2 and in Table A.5.
The three categories presented in Table A.1 apply to spaces where persons are exposed to the same thermal
environment. It is an advantage if some kind of individual control of the thermal environment can be
established for each person in a space. Individual control of the local air temperature, mean radiant
temperature or air velocity can contribute to balancing the rather large differences between individual
requirements and consequently can lead to fewer dissatisfied.
Modification of the clothing can also contribute to balance individual differences. The effect on the optimum
operative temperature of adding or removing different garments is described in Table C.2.
A.2 Operative temperature range
For a given space there exists an optimum operative temperature corresponding to PMV = 0, depending on
the activity and the clothing of the occupants. Figure A.1 shows the optimum operative temperature and the
permissible temperature range as a function of clothing and activity for each of the three categories. The
optimum operative temperature is the same for the three categories, while the permissible range around the
optimum operative temperature varies.
ISO 7730:2005(E)
The operative temperature at all locations within the occupied zone of a space should at all times be within the
permissible range. This means that the permissible range should cover both spatial and temporal variations,
including fluctuations caused by the control system.
Figure A.1 applies for a relative humidity of 50 %; however, in moderate environments the air humidity has
only a modest impact on the thermal sensation. Typically, a 10 % higher relative humidity and a 0,3 °C higher
operative temperature are perceived as being warmer in equal measure.
The PDs in Table A.1 are not additive. In practice, a higher or lower number of dissatisfied persons may be
found when using subjective questionnaires in field investigations (see ISO 10551).
The air velocity in the space is assumed to be < 0,1 m/s. The relative air velocity, v , caused by body
ar
movement is estimated to be zero for a metabolic rate, M, less than 1 met and v = 0,3 (M − 1) for M > 1 met.
ar
The diagrams are determined for a relative humidity = 50 %, but the humidity only has a slight influence on the
optimum and permissible temperature ranges.
A.3 Local thermal discomfort
Figure A.2 give ranges for local thermal discomfort parameters for the three categories presented in Table A.1.
The max. allowable mean air velocity is a function of local air temperature and turbulence intensity. The
turbulence intensity may vary between 30 % and 60 % in spaces with mixed-flow air distribution. In spaces
with displacement ventilation or without mechanical ventilation, the turbulence intensity may be lower.

Category A: PPD < 6 %
14 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Category B: PPD < 10 %
Category C: PPD < 15 %
The diagrams also show the range around the optimum temperature for the three categories.
Key
PPD predicted percentage dissatisfied, %
X basic clothing insulation, in clothing units, (clo)
X′ basic clothing insulation, in clothing units, m⋅°C/W
Y metabolic rate, in metabolic units, (met)
Y′ metabolic rate, in metabolic units, W/m
Figure A.1 — Optimum operative temperature as function of clothing and activity
ISO 7730:2005(E)
Category A: DR = 10 % Category B: DR = 20 % Category C: DR = 30 %
Key
t local air temperature, °C
a,l
v local mean air velocity, m/s
a,l
Tu turbulence intensity, %
Figure A.2 — Max. allowable mean air velocity as function of local air temperature
and turbulence intensity
Tables A.2, A.3 and A.4 give values for the local thermal discomfort causes: vertical air temperature difference,
warm/cold floor and radiant temperature asymmetry.
Table A.2 — Vertical air temperature difference between head and ankles
a
Category Vertical air temperature difference
°C
A < 2
B < 3
C < 4
a
1,1 and 0,1 m above floor.
Table A.3 — Range of floor temperature
Category Floor surface temperature range
°C
A 19 to 29
B 19 to 29
C 17 to 31
16 © ISO 2005 – All rights reserved

ISO 7730:2005(E)
Table A.4 — Radiant temperature asymmetry
Category Radiant temperature asymmetry
°C
Warm ceiling Cool wall Cool ceiling Warm wall
A < 5 < 10 < 14 < 23
B < 5 < 10 < 14 < 23
C < 7 < 13 < 18 < 35
A.4 Design criteria for different types of space — Examples
The design criteria specified in Table A.5 are derived under certain assumptions. For the thermal environment,
the criteria for the operative temperature are based on typical levels of activity, for clothing of 0,5 clo during
summer (“cooling season”) and 1,0 clo during winter (“heating season”). The criteria for the mean air velocity
apply for a turbulence intensity of approximately 40 % (mixing ventilation). The design criteria are valid for the
occupancy conditions as given, but could also be applicable to other types of spaces used in similar ways.
Table A.5 — Example design criteria for spaces in various types of building
a
Type of Activity Category Operative temperature Maximum mean air velocity
building/space W/m °C m/s
Summer Winter Summer Winter
(cooling season) (heating season) (cooling season) (heating season)
Single office
A 24,5 ± 1,0 22,0 ± 1,0 0,12 0,10
Landscape office
Conference room
70 B 24,5 ± 1,5 22,0 ± 2,0 0,19 0,16
Auditorium
Cafeteria/restaurant
b
C 24,5 ± 2,5 22,0 ± 3,0 0,24 0,21
Classroom
b
Kindergarten 81 A 23,5 ± 1,0 20,0 ± 1,0 0,11 0,10
b
B 23,5 ± 2,0 22,0 ± 2,5 0,18 0,15
b
C 23,5 ± 2,5 22,0 ± 3,5 0,23 0,19
b
Department store 93 A 23,0 ± 1,0 19,0 ± 1,5 0,16 0,13
b
B 23,0 ± 2,0 19,0 ± 3,0 0,20 0,15
b
C 23,0 ± 3,0 19,0 ± 4,0 0,23 0,18

a
The maximum mean air velocity is based on a turbulence intensity of 40 % and air temperature equal to the operative temperature
according to 6.2 and Figure A.2. A relative humidity of 60 % and 40 % is used for summer and winter, respectively. For both summer
and winter a lower temperature in the range is used to determine the maximum mean air velocity.

b
Below 20 °C limit (see Figure A.2).
ISO 7730:2005(E)
Annex B
(informative)
Metabolic rates of different activities
Further information on metabolic rates is given in ISO 8996. That elderly people often have a lower average
activity than younger people also needs to be taken into account.
Table B.1 — Metabolic rates
Activity Metabolic rate
W/m met
Reclining 46 0,8
Seated, relaxed 58 1,0
Sedentary activity (office, dwelling, school, laboratory) 70 1,2
Standing, light activity (shopping, laboratory, light industry) 93 1,6
Standing, medium activity (shop assistant, domestic work, machine work) 116 2,0
Walking on level ground:
2 km/h 110 1,9
3 km/h 140 2,4
4 km/h 165 2,8
5 km/h 200 3,4
18 © ISO 2005 – All rights reserved

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