EN 14750:2024

Railway applications - Air conditioning for urban, suburban and regional rolling stock: Comfort parameters and type tests

This document establishes thermal comfort parameters for areas accessible to passengers and staff on railway vehicles.
This document also specifies conditions, performance values and the comfort parameter validation methods.
This document is applicable to urban (metro, tramway), suburban and/or regional vehicles equipped with cooling and/or heating/ventilation systems. This document does not apply to main line vehicles and driver’s cabs which are considered in separate Standards.

Bahnanwendungen - Luftbehandlung in Schienenfahrzeugen des städtischen-, Vorort- und Regionalverkehrs - Behaglichkeitsparameter und Typprüfungen

Dieses Dokument legt thermische Behaglichkeitsparameter für Bereiche fest, die für Fahrgäste und Personal in Schienenfahrzeugen zugänglich sind.
Dieses Dokument legt zudem Bedingungen, Leistungswerte und Verfahren zur Validierung von Behaglichkeitsparametern fest.
Dieses Dokument ist anwendbar für Fahrzeuge städtischer Schienenbahnen (U-Bahnen, Straßenbahnen), Vorort- und/oder Regionalbahnen, die mit einer Kühlanlage und/oder Heizungs-/Lüftungsanlage ausgerüstet sind. Dieses Dokument ist nicht anwendbar für Vollbahnen und Führerräume, die Gegenstand gesonderter Normen sind.

Applications ferroviaires - Conditionnement de l'air pour matériel roulant urbain, de banlieue et régional : Paramètres de confort et essais de type

Le présent document établit les paramètres de confort thermique pour les zones des véhicules ferroviaires, accessibles aux voyageurs et au personnel de bord.
Le présent document précise également les conditions, les valeurs de performance et les méthodes de validation des paramètres de confort.
Le présent document est applicable aux véhicules urbains (métro, tramway), de banlieue et/ou régionaux équipés de systèmes de réfrigération et/ou de chauffage/ventilation. Le présent document ne s'applique pas aux véhicules de grandes lignes et les cabines de conduite qui font l'objet de normes spécifiques.

Železniške naprave - Klimatske naprave v železniških vozilih za mestni, primestni in regionalni promet - Parametri za določanje udobja in preskusi tipa

Ta dokument določa parametre za določanje toplotnega udobja v območjih, ki so dostopna potnikom in osebju v železniških vozilih.
Določa tudi pogoje, vrednosti zmogljivosti in metode za potrjevanje teh parametrov.
Ta dokument se uporablja za vozila za mestni (metroji, tramvaji), primestni in/ali regionalni železniški promet, ki so opremljena s sistemi za hlajenje in/ali ogrevanje/prezračevanje. Ne uporablja se za vozila na glavnih železniških progah in vozniške kabine, ki jih obravnavajo ločeni standardi.

General Information

• Status: Published
• Publication Date: 17-Dec-2024
• ICS: 13.040.20 - Ambient atmospheres
• ICS: 45.140 - Metro, tram and light rail equipment
• Technical Committee: CEN/TC 256 - Railway applications
• Drafting Committee: CEN/TC 256/WG 8 - Air conditionning, Heating and Ventilation
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 18-Dec-2024
• Due Date: 02-Jan-2024
• Completion Date: 18-Dec-2024
• Directive: 2008/57/EC - Directive 2008/57/EC of the European Parliament and of the Council of 17 June 2008 on the interoperability of the rail system within the Community (Recast)
• Directive: 2016/797/EU - Directive (EU) 2016/797 of the European Parliament and of the Council of 11 May 2016 on the interoperability of the rail system within the European Union (Text with EEA relevance)
• Mandate: M/486 - Mandate for programming and standardisation addressed to the European standardisation bodies in the field of urban rail
• Ref Project: SIST EN 14750:2025 - Railway applications - Air conditioning for urban, suburban and regional rolling stock : Comfort parameters and type tests

Relations

• Replaces: EN 14750-2:2006 - Railway applications - Air conditioning for urban and suburban rolling stock - Part 2: Type tests
• Effective Date: 19-Jan-2023
• Replaces: EN 14750-1:2006 - Railway applications - Air conditioning for urban and suburban rolling stock - Part 1: Comfort parameters
• Effective Date: 19-Jan-2023

Overview

EN 14750:2024 (identical to EN 14750:2024) specifies thermal comfort parameters, performance requirements and type test methods for air conditioning systems used in urban, suburban and regional rolling stock (metro, tramway, suburban and regional trains). It defines the environmental conditions, validation procedures and acceptance criteria for passenger- and staff-accessible areas of vehicles equipped with heating, ventilation and/or cooling systems. This standard excludes main-line vehicles and driver’s cabs, which are covered by other standards.

Key Topics and Requirements

• Vehicle categories: Introduces three categories-Urban, Suburban and Regional-to tailor performance and test requirements to use case and duty cycle.
• Comfort parameters: Defines the comfort envelope for interior temperature, humidity, air speed and local annexes (local zones) and introduces a global Comfort Level (CL) index for an overall assessment.
• Exterior condition ranges: Specifies normal and extended exterior temperature ranges with associated functional and comfort performance requirements.
• Performance and control: Covers heating, cooling, pre-heating/pre-cooling, standby operation and interior temperature setpoint regulation, including new regulation tests to assess control quality.
• Validation & testing: Details validation routes including laboratory climatic tests (pre-heating, pre-cooling, regulation, steady-state and extreme-condition tests), air movement tests, measurement methods and distribution of measuring points.
• Measurements and equipment: Specifies measuring instruments and methods for temperature, relative humidity, air speed, flow rates, simulated vehicle speed and equivalent solar energy.
• Simulation allowance: Enables validation of comfort parameters using simulation methods and defines requirements for simulation setup and assessment.
• Complementary requirements: Includes heat transfer coefficient, condensation prevention, solar factor of windows, sealing against water/snow, and fresh air flow considerations.

Practical Applications and Who Uses This Standard

EN 14750:2024 is essential for:

• Rolling stock manufacturers designing HVAC systems for metro, tram, suburban and regional vehicles
• HVAC suppliers and system integrators specifying climate control components and control logic
• Test laboratories and certification bodies conducting type tests and climatic validation
• Train operators and asset owners defining procurement and acceptance criteria for passenger comfort
• Maintenance and commissioning teams verifying in-service performance against documented criteria

Using this standard helps ensure consistent passenger comfort, energy-efficient HVAC design and repeatable test procedures across European markets.

Related Standards (if applicable)

• Supersedes: EN 14750-1:2006 and EN 14750-2:2006
• Normative references cited in the document include EN ISO 7726:2001 (ergonomics - measurement instruments) and EN ISO 19659-1:2023 (HVAC for railway applications)
• Part of the CEN/TC 256 railway applications portfolio

Keywords: EN 14750:2024, railway air conditioning, thermal comfort, urban rolling stock, type tests, HVAC railway standard, Comfort Level (CL).

Standards Content (Sample)

SLOVENSKI STANDARD
01-marec-2025
Železniške naprave - Klimatske naprave v železniških vozilih za mestni, primestni
in regionalni promet - Parametri za določanje udobja in preskusi tipa
Railway applications - Air conditioning for urban, suburban and regional rolling stock :
Comfort parameters and type tests
Bahnanwendungen - Luftbehandlung in Schienenfahrzeugen des städtischen-, Vorort-
und Regionalverkehrs - Behaglichkeitsparameter und Typprüfungen
Applications ferroviaires - Conditionnement de l'air pour matériel roulant urbain, de
banlieue et régional : Paramètres de confort et essais de type
Ta slovenski standard je istoveten z: EN 14750:2024
ICS:
23.120 Zračniki. Vetrniki. Klimatske Ventilators. Fans. Air-
naprave conditioners
45.060.01 Železniška vozila na splošno Railway rolling stock in
general
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN 14750
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2024
EUROPÄISCHE NORM
ICS 13.040.20; 45.140 Supersedes EN 14750-1:2006, EN 14750-2:2006
English Version
Railway applications - Air conditioning for urban,
suburban and regional rolling stock: Comfort parameters
and type tests
Applications ferroviaires - Conditionnement de l'air Bahnanwendungen - Luftbehandlung in
pour matériel roulant urbain, de banlieue et régional : Schienenfahrzeugen des städtischen-, Vorort- und
Paramètres de confort et essais de type Regionalverkehrs - Behaglichkeitsparameter und
Typprüfungen
This European Standard was approved by CEN on 27 October 2024.

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 CEN-CENELEC Management Centre 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 CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2024 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN 14750:2024 E
worldwide for CEN national Members.

Contents Page
European foreword . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Parameter selection . 13
5 Vehicle categories . 13
6 Comfort parameters . 15
7 Exterior conditions. 16
7.1 Generalities . 16
7.2 Mean exterior temperature range with comfort criteria . 16
7.3 Mean exterior temperature range with functional criteria . 17
8 Performance of the heating and cooling installations . 17
8.1 Design passenger load . 17
8.2 Heating . 17
8.3 Pre-heating . 17
8.4 Cooling . 18
8.5 Pre-cooling . 18
8.6 Stand by operation . 18
9 Control . 19
9.1 General. 19
9.2 Interior temperature setpoint (T ) . 19
ic
9.3 Interior temperature setpoint (T ) for vehicles without cooling . 19
ic
10 Comfort condition requirements . 19
10.1 Requirements for comfort zone. 19
10.2 Requirements for local annexes (T ) . 29
Loc
10.3 Air quantities and quality . 30
11 Complementary requirements . 30
11.1 Heat transfer coefficient (k) . 30
11.2 Condensation . 31
11.3 Solar factor (g) of the windows . 31
11.4 Sealing against water and snow . 31
12 Validation . 31
12.1 General. 31
12.2 Test levels . 31
12.3 Selection of tested vehicles . 32
12.4 Assessment of comfort criteria based on simulation . 32
13 Preliminary verifications . 34
14 Air movement tests . 34
14.1 General remarks . 34
14.2 Air flow rates . 34
14.3 Visualization of the air flow direction . 34
14.4 Air speed test . 35
15 Climatic tests . 35
15.1 General remarks . 35
15.2 Pre-heating test . 36
15.3 Pre-cooling test. 36
15.4 Regulation test . 36
15.5 Steady-state tests . 37
15.6 Tests at extreme exterior operating conditions . 38
15.7 Complementary tests . 38
16 Methods of measurement − Measuring instruments . 41
16.1 General remarks . 41
16.2 Temperatures . 41
16.3 Relative humidity . 41
16.4 Air speed . 42
16.5 Air flow rate . 42
16.6 Simulated speed of the vehicle . 42
16.7 Equivalent solar energy . 42
16.8 Energy consumption and power rating . 42
17 Characteristics of the test equipment . 42
17.1 General remarks . 42
17.2 Occupation . 42
17.3 Temperature and uniformity of the climatic chamber and climatic wind tunnel . 43
17.4 Relative exterior humidity . 43
17.5 Simulation of exterior air speed . 43
17.6 Equivalent solar energy . 43
18 Distribution of measuring points . 46
18.1 General . 46
18.2 Comfort envelope temperature measuring points . 46
Annex A (normative) Form for parameters selection . 47
Annex B (normative) Regulation curves for the interior temperature setpoint . 51
Annex C (normative) Acceptable air speed . 53
Annex D (normative) Maximum Relative interior humidity in the comfort envelope . 55
Annex E (normative) Heat emitted by a person. 57
Annex F (normative) Exterior conditions for climatic zones . 60
Annex G (normative) Fresh air flow . 62
Annex H (normative) Test programme for TL1 . 64
Annex I (normative) Test programme for TL2 and TL3 . 66
Annex J (normative) Equivalent solar energy (Simulation of solar exposure) . 75
Annex K (normative) Location of the measuring points used for the determination of the
mean interior temperature in the comfort envelope (T ), horizontal (ΔT ) and
im H
vertical (ΔT ) range of the extreme interior air temperatures, floor surface
V
temperature (T _ ), relative interior humidity (RH ), interior CO concentration (C )
S Fl im 2 im
in the comfort envelopes and local annexes . 76
Annex L (normative) Location of the measuring points used for the determination of surface
temperatures . 81
Annex M (normative) Location of other sensors . 84
Annex N (informative) Coefficient k . 88
Annex O (normative) Calculation method of the comfort level CL. 89
Annex P (informative) Simulation . 102
Annex Q (normative) Set-up of the simulation . 108
Annex R (informative) Abbreviations . 114
Bibliography . 117

European foreword
This document (EN 14750:2024) has been prepared by Technical Committee CEN/TC 256 “Railway
applications”, 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 June 2025, and conflicting national standards shall be
withdrawn at the latest by June 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN 14750-1:2006 and EN 14750-2:2006.
In comparison with the previous edition, the following technical modifications have been made:
• Creation of 3 vehicle categories (Urban, Suburban and Regional) to define the corresponding
performances;
• Definition of normal and extended ranges of exterior temperatures with corresponding
performances;
• Usage of an index Comfort Level (CL) to provide a global view of the climatic comfort;
• Improvement of the validation process with new regulation tests. The purpose is to assess the quality
of the regulation of the system;
• Introduction of the process of validation of the climatic comfort parameters by simulations.
This document has been prepared under a Standardization Request addressed to CEN by the European
Commission.
Any feedback and questions on this document should be directed to the users’ national standards body.
A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organisations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia,
Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland,
Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North
Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the United
Kingdom.
1 Scope
This document establishes thermal comfort parameters for areas accessible to passengers and staff on
railway vehicles.
This document also specifies conditions, performance values and the comfort parameter validation
methods.
This document is applicable to urban (metro, tramway), suburban and/or regional vehicles equipped
with cooling and/or heating/ventilation systems. This document does not apply to main line vehicles and
driver’s cabs which are considered in separate Standards.
2 Normative references
The following documents are referred to in the text in such a way that some or all their content constitutes
requirements 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.
EN ISO 7726:2001, Ergonomics of the thermal environment — Instruments for measuring physical
quantities (ISO 7726:1998)
EN ISO 19659-1:2023, Railway applications — Heating, ventilation and air conditioning systems for rolling
stock — Part 1: Terms and definitions (ISO 19659-1:2017)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in EN ISO 19659-1:2023 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
NOTE Refer to informative Annex R for more information on abbreviations.
3.1
air conditioning installation
all equipment of Heating Ventilation Air Conditioning (HVAC) system involved to reach the thermal
comfort
Note 1 to entry: Refer to EN ISO 19659-1:2023.
3.2
interior temperature setpoint
T
ic
target value for interior air temperature
3.3
normal interior temperature setpoint
T
ic,0
target value for interior air temperature according to regulation curve
Note 1 to entry: Refer to 9.2 and normative Annex B.
3.4
interior temperature setpoint offset
T
ic,Off
adjustment of the interior temperature setpoint
Note 1 to entry: Refer to 9.2.
3.5
mean interior temperature
Tim
arithmetic mean of the interior temperatures of one comfort zone and measured 1,10 m above the floor
as specified in the procedure described in normative Annex K
3.6
mean exterior temperature
T
em
arithmetic mean of the exterior temperatures measured according to the procedure described in
normative Annex M
3.7
comfort envelope
areas designed for occupation by passengers, excluding local annexes
Note 1 to entry: If a gangway is designed for passengers to dwell inside, it is part of comfort envelope.
3.8
comfort zone
subset of the comfort envelope on one vehicle limited by steps or ramp with a total floor height difference
of at least 0,3 m, partition wall, vestibule, interior door or gangway
Note 1 to entry: Tram is considered as one comfort zone.
Note 2 to entry: The comfort zone is divided in subzones to define the position of the measuring points (refer to
normative Annex K especially Figure K.1 for the description of the subzones).
3.9
local annex
place where passenger stays briefly or passes through
EXAMPLE 1 toilet compartment (WC)
EXAMPLE 2 baby change area
EXAMPLE 3 aisle
EXAMPLE 4 vestibule
Note 1 to entry: If a gangway is closed by two doors it is not considered as a local annex and no comfort criterion
is applied.
Note 2 to entry: For multi-purpose areas, the classification as comfort zone or local annex have to be agreed.
3.10
heat transfer coefficient
k
ratio between the thermal power per unit of surface area and the prevailing difference in temperature
(T ) and (T ) across the relevant walls of the vehicles
im em
Note 1 to entry: The coefficient k takes account of the efficiency of the insulation of the exterior walls and the effect
of the infiltration of air caused by the non-airtightness of the vehicle in motion (doors, windows, various openings)
and is applicable to all or part of the vehicle.
Note 2 to entry: This value is expressed in W/(m ·K).
3.11
equivalent solar irradiation
total heat received by 1 m surface perpendicular to the radiation emitted by a luminous source (solar
equivalent) and this, when inclined at an angle of 30° to the horizontal
3.12
stand by operation
mode under which a predetermined interior temperature range is maintained when the vehicle is not in
commercial service
3.13
design passenger load
number of passengers used to size the air conditioning installation
3.14
free cooling
provision of cooling using potential increase of fresh airflow and without use of refrigerant circuit
3.15
vestibule
area with at least one exterior door separated from the comfort envelope by steps or ramp with a total
floor height difference of at least 0,3 m, interior door(s), full partition wall(s) and without permanent
seats
3.16
mean interior CO2 concentration

Cim
arithmetic mean of the interior CO concentration measured at the centre of each subzone of each
comfort zone and at the height of 1,1 m
Note 1 to entry: Refer to normative Annex K.
3.17
climatic zone
climatic conditions used to size the HVAC system
Note 1 to entry: Refer to 7.1, 7.2 and 7.3 for the definition of design and the extreme conditions.
3.18
mean interior absolute humidity
x
im
arithmetic mean of the absolute humidity calculated with the local relative humidity and corresponding
temperature of the comfort zone measured at 1,1 m above the floor as specified in normative Annex K
3.19
mean interior relative humidity
RH
im
relative interior humidity calculated with the interior mean temperature (Tim) and absolute interior
humidity (x ) per comfort zone
im
Figure 1 — Process to calculate RH
im
Note 1 to entry: The absolute humidity is given by Formula (1):
0,622××RH P
Loc Sat _Loc
(1)
X =
Loc
100×P −RH ×P
Atm Loc Sat _Loc
Where
XLoc Local absolute humidity in kilogram of water per kilogram of dry air [kg of
water/kg dry air];
RHLoc Local relative hygrometry in percentage [% value from 0 to 100];
P Local pressure of saturated steam calculated with T in pascals [Pa];
Sat_Loc Loc
P Local atmospheric pressure in pascals [Pa];
Atm
TLoc Local temperature in Celsius degrees [°C].
Note 2 to entry: The pressure of saturated steam is given by the Formula (2):
 4030,183
16,6536−
 
T +235
 Loc 
Pe1000 × (2)
Sat _Loc
Where
PSat_Loc Local pressure of saturated steam in pascals [Pa];
TLoc Local temperature in Celsius degrees [°C].
EXAMPLE 1 At Tem = 35°C 50 % at atmospheric pressure of 101 325 Pa, PSat = 5 623,7 Pa corresponds to
X = 0,017 75 kg of water/kg dry air or 17,75 g of water/kg dry air.
Note 3 to entry: The mean interior temperature is given by the Formula (3):
N
TT=
(3)
im ∑ Loc _i
N
i=1
Where
T Mean interior temperature in Celsius degrees [°C];
im
N Number of local temperature involved in mean interior temperature calculation [number];
TLoc_i Local temperature in Celsius degrees [°C].
Note 4 to entry: The mean interior absolute humidity is given by the Formula (4):
N
XX=
(4)
im ∑ Loc _i
N
i=1
Where
Xim Mean interior absolute humidity in kilogram of water per kilogram of dry air [kg of
water/kg dry air];
N Number of local absolute humidity involved in mean interior absolute humidity
calculation [number];
XLoc_i Local absolute humidity in kilogram of water per kilogram of dry air [kg of water/kg dry
air].
Note 5 to entry: The mean relative hygrometry is given by the Formula (5):
100××XP
im Atm
RH = (5)
im
PX×+0,622
( )
Sat _im im
Where
RHim Mean relative hygrometry in % [value from 0 to 100];
Xim Mean absolute humidity in kilogram per kilogram of dry air [kg of water/kg dry
air];
PAtm Local atmospheric pressure in pascals [Pa];
P Pressure of saturated steam calculate with the mean interior temperature in
Sat_im
pascals [Pa].
EXAMPLE 2 In one comfort zone we have these measurements of temperature and relative humidity on 9 points
(refer to Table 1). The atmospheric pressure is 101 325 Pa.
=
Table 1 — Parameters considered in the example
Unit 1 2 3 4 5 6 7 8 9
TLoc °C 25,1 25,2 24,7 24,8 25,5 24,1 24,5 26,1 25,3
RHLoc % 50,8 55,6 57,3 54,8 56,9 59,2 56,1 48,1 48,9
PSat_Loc Pa 3186,3 3205,3 3111,1 3129,8 3263,0 3001,3 3074,2 3381,1 3224,5
kg of
water/kg
XLoc dry air 0,0101 0,0111 0,0111 0,0107 0,0116 0,0111 0,0108 0,0101 0,0098
Note 6 to entry: The calculated values are indicated in Table 2:
Table 2 — Calculated values in the example
Unit Value
T °C 25,0
im
kg of water
X /kg dry air 0,0107
im
P Pa 3173,7
Sat_im
RH % 54,1
im
3.20
mean exterior absolute humidity
x
em
arithmetic mean of the absolute humidity calculated with the local relative humidity RH and
Loc
corresponding temperature as specified in normative Annex M
3.21
mean exterior relative humidity
RH
em
relative exterior humidity calculated with the exterior mean temperature (T ) and absolute exterior
em
humidity (x )
em
Figure 2 — Process to calculate RH
em
3.22
subzone
portion of the comfort zone only used for the location of the test sensors
3.23
mean air speed of vehicle surrounding flow
arithmetic mean of the air speed measured at 6 points outside the vehicle at the distance of 0,1 m from
the wall of the vehicle
Note 1 to entry: The mean air speed of vehicle surrounding flow is used for measurements at standstill.
Note 2 to entry: See normative Annex M for the position of the 6 measuring points.
3.24
mean air speed of interior flow
arithmetic mean of the air speed measured at 6 points inside the vehicle at the distance of 0,1 m from the
wall of the vehicle
Note 1 to entry: See normative Annex M.
3.25
vehicle interior temperature
T
iv
arithmetic mean of all interior temperatures of all different comfort zones of the vehicle measured at
1,1 m above the floor as specified in the procedure described in normative Annex K
3.26
vehicle interior absolute humidity
x
iv
arithmetic mean of the absolute humidity calculated with the local relative humidity in all different
comfort zones of the vehicle and corresponding temperature measured at 1,1 m above the floor as
specified in normative Annex K
3.27
vehicle interior relative humidity
RH
iv
relative interior humidity calculated with the interior mean temperature (T ) and absolute interior
iv
humidity (x )
iv
3.28
control settling time
t
CS
maximum allowed time for achieving stabilised condition after a change of Tic
3.29
stabilised condition
condition achieved when the difference between the maximum and the minimum values of T is less than
im
or equal to the defined limits
Note 1 to entry: Refer to 10.1.1.1.
3.30
single result
Xijk
value measured during evaluation period which gives the worst single conformity level, in a single
measuring point k or the value calculated over all single measuring points from a group k related to one
specific T , in a single test i, for a single comfort parameter j, considered without regarding measuring
im
tolerances
3.31
single conformity level
Y
ijk
conformity level for one comfort parameter j, in one specific test i, at one measuring point k or group of
measuring points k, in relation to the corresponding quality limits q and q
1 2
3.32
Comfort Level
CL
index used to estimate the comfort of a vehicle
Note 1 to entry: Refer to Annex O for the calculation of this index.
4 Parameter selection
Table A.1 shall be completed to define all parameters needed to apply this document.
5 Vehicle categories
The contractual specification shall detail the operational scenario and vehicle category (refer to
normative Annex A).
For guidance, the criteria to classify a vehicle for thermal comfort are given in Figure 3 and in Table 3.
The limits of relevant comfort parameters vary with the applicable category.
• Urban (category U): Vehicles which operate inside the city (e.g. tram, metro).
• Suburban (category S): Vehicles which operate inside and in the surrounding of the city.
• Regional (category R): Vehicles which operate between cities with intermediate stops.
• Main line: Vehicles which operate between cities usually with a limited number of intermediate
stops.
Key
1 Suburbs
2 City 1
3 City 2
4 Urban
5 Suburban
6 Main Line
7 Regional
8 Stops
Figure 3 — Typical operating areas of different vehicle categories
Table 3 — Vehicle categories for passenger area
Typical values Urban Suburban Regional Main Line
Standard EN 14750 EN 14750 EN 14750 EN 13129 [3]
Category U Category S Category R
Time between stops < 3min < 10min 5 – 30min > 30min
Design passenger load all seats all seats all seats all seats
occupied occupied occupied occupied,
(excluding (excluding including tip- including tip-
tip-up seats tip-up seats up seats and up seats and
and and wheelchairs wheelchairs
wheelchairs) wheelchairs)
2 2
+ 2p/m + 2p/m
Probability of removing Low Low Medium High
clothing to suit thermal
conditions
If the vehicle’s operation is foreseen to be in more than one category, it is recommended to select the
most appropriate vehicle category for thermal comfort.
The ability to achieve thermal comfort is influenced by the type of vehicle. It should be recognized that it
may not be practicable to take a level of thermal comfort from one vehicle category and apply it to a
different vehicle category. For example, it would unlikely be practicable to provide a main line vehicle
level of thermal comfort within a metro vehicle.
6 Comfort parameters
Thermal comfort is assessed based on the following interior climate parameters:
• air temperature,
• air speed,
• relative humidity,
• surface temperatures,
as a function of thermal exchange between the interior climate and a seated or standing person dressed
normally in accordance with Figure E.1 and as a function of the exterior climatic conditions which have
an indirect effect.
The evaluation of the comfort parameters shall be done by quality limits q and q .
1 2
The minimum comfort level for each single test and for each car to be applied should be defined in the
contractual specification. In the absence of such a definition, 85 % shall be reached at least.
NOTE 1 q1 describes the targets for the comfort parameters to reach the thermal comfort and q2 describes the
maximum acceptable limits for the comfort parameters.
NOTE 2 The quality limits (normal or extended) are defined in Clause 10 as a function of the mean exterior
temperature (Tem) in accordance with Table 4 and Table 5.
NOTE 3 Refer to Annex O for the details of the calculation of the comfort level.
7 Exterior conditions
7.1 Generalities
A climatic zone for winter and a climatic zone for summer shall be selected from Table F.1 (design
conditions for winter) and Table F.3 (design conditions for summer). The selection should be based on
local climatic conditions in which the system operates and should be specified in the contractual
specification.
NOTE 1 To select the appropriate climatic zone, also refer to local climate databases.
The most appropriate climatic zone should be selected to avoid the oversizing of the HVAC system.
For tunnel operation (absence of sun load) the mean exterior temperature and the corresponding relative
exterior humidity shall be indicated in the contractual specification.
NOTE 2 Generally the mean exterior temperature selected for tunnel operation corresponds to the maximum
and minimum temperature observed in the tunnel.
The extreme exterior conditions for winter (Table F.2) shall correspond with the climatic zone selected
from Table F.1.
The extreme exterior conditions for summer (Table F.4) and operational limits for summer (Table F.5)
shall correspond with the climatic zone selected from Table F.3.
The thermal impact of the vehicle or / and of the infrastructures on the HVAC system shall be considered.
The thermal impact of the HVAC system on other equipment of the vehicle shall be considered.
7.2 Mean exterior temperature range with comfort criteria
The comfort parameters shall be satisfied within the range of exterior conditions of the selected climatic
zones considering the limits of performance defined in Clause 8.
The normal range represents the most commonly occurring range of mean exterior temperature and
therefore is highly important for the quality of comfort.
The extended range is valid for more severe exterior conditions that appear not so frequently, where a
slight decrease of thermal comfort is acceptable.
Table 4 — Mean exterior temperature range for winter
Local Winter (LW) Zone Normal range Extended range
[°C] [°C]
LW.1 T ≥ 5 0 ≤ T < 5
em em
LW.2 T ≥ 0 −10 ≤ T < 0
em em
LW.3 T ≥ −10 −20 ≤ T < −10
em em
LW.4 T ≥ −15 −30 ≤ T < −15
em em
LW.5 T ≥ −20 −40 ≤ T < −20
em em
Table 5 — Mean exterior temperature range for summer
Local Summer (LS) Zone Normal range Extended range
[°C] [°C]
LS.1 T ≤ 35 35 < T ≤ 40
em em
LS.2 T ≤ 28 28 < T ≤ 35
em em
LS.3 T ≤ 26 26 < T ≤ 32
em em
LS.4 T ≤ 22 22 < T ≤ 28
em em
7.3 Mean exterior temperature range with functional criteria
Down to the temperature given in Table F.2 the HVAC system shall be able to operate at the same
functional status without active reduction of the capacity as for the design point in heating or to provide
the same heating capacity as needed for the design point in heating.
NOTE 1 The interior conditions as defined in Clause 10 do not need to be complied with during these extreme
conditions.
The HVAC system shall be able to continue to operate at least at the same functional status without active
reduction of the capacity (refer to note 2) as for the design point in cooling up to the conditions given in
Table F.4.
The HVAC system shall also continue to operate in at least reduced cooling mode up to the conditions
given in Table F.5.
NOTE 2 Active reduction of the capacity could be for example usage of hot gas by-pass, power supply frequency
reduction, reduction of the supply airflow.
It is allowed to increase the supply airflow or the condenser airflow under these conditions.
8 Performance of the heating and cooling installations
8.1 Design passenger load
For category R (see Clause 5), this passenger load is corresponding to all seats occupied including tip-up
seats and wheelchairs.
For categories S and U (see Clause 5), this passenger load is corresponding to all seats occupied
(excluding tip-up seats and wheelchairs) and 2 passengers/m for standing areas.
8.2 Heating
At the mean exterior temperature for the climatic zone (Table F.1), at the maximum vehicle operational
speed, without solar irradiation and with the most challenging combination of occupation and
corresponding fresh air flow (see normative Annex G) for the heating capacity, the mean vehicle interior
temperature (T ) in the comfort envelope shall be at least +18 °C for category R vehicles, +15 °C for
iv
category S vehicles and +10 °C for category U vehicles.
If any other conditions are indicated in normative Annex A (e.g. tunnel), it shall also be considered for the
sizing and testing of the air conditioning installation.
8.3 Pre-heating
The pre-heating conditions and performance should be defined in the contractual specification.
Pre-heating conditions and performance are: maximum available electrical power at nominal voltage,
mean exterior temperature, a mean interior temperature at starting, mean interior temperature to be
achieved within the maximum pre-heating time (time begins when the vehicle is switched on). It is
recommended to not exceed the heating capacity defined in 8.2.
In the absence of any of the above specifications, the pre-heating time depends on the performance
defined in 8.2. In this case it is recommended to use a T of T – 2 K to stop the pre-heating. If the system
im ic
is not able to reach this interior temperature, the pre-heating test is stopped when the mean interior
temperature does not increase more than 0,5 K within 30 min.
8.4 Cooling
At the mean exterior temperature for the climatic zone (Table F.3), including solar irradiation, with
vehicle at standstill, with all doors and windows closed, for design passenger load (refer to definition 3.13
and 8.1) and corresponding fresh air flow (see normative Annex G), the mean vehicle interior
temperature (Tiv) shall be less than or equal to the values in Table 6.
The vehicle relative interior humidity (RH ), corresponding to the temperature T , shall be less or equal
iv iv
to the corresponding value of the curve q defined in Figure D.1.
Table 6 — Maximum mean vehicle interior temperature at the design conditions
LS Zone Category R Category S Category U

LS.1 +27 °C +30 °C +32 °C
LS.2 +27 °C +30 °C +32 °C
LS.3 +26 °C +28 °C +31 °C
LS.4 +25 °C +26 °C +29 °C
If any other conditions are indicated in normative Annex A, (e.g. tunnel), it shall also be considered for
the sizing and testing of the air conditioning installation.
8.5 Pre-cooling
The pre-cooling conditions and performance should be defined in the contractual specification.
Pre-cooling conditions and performance are: Procedure for starting pre-cooling, maximum available
electrical power at nominal voltage, mean exterior temperature and mean interior temperature to be
achieved within the maximum pre-cooling time (time begins when the vehicle is switched on). It is
recommended to not exceed the cooling capacity defined in 8.4.
In the absence of any of the above specifications, the pre-cooling time depends on the performance
defined in 8.4. In this case it is recommended to use a T of T + 2K to stop the pre-cooling. If the system
im ic
is not able to reach this interior temperature, the pre-cooling test is stopped when the mean interior
temperature doesn’t decrease more than 0,5 K within 30 min.
8.6 Stand by operation
If stand by operation is required, the requirements and the temperature range shall be detailed in the
contractual specifications.
In absence of any indication regarding the stand by operation and performance in the contractual
specification, the system shall maintain Tim above +3 °C.
During summer conditions it is recommended to use free cooling instead of the refrigerant circuit.
As a recommendation for category R, the system should be able to maintain T lower 30 °C in summer
im
design conditions.
9 Control
9.1 General
Each vehicle shall be fitted with a regulation system which shall enable the comfort parameters defined
in this document to be achieved.
9.2 Interior temperature setpoint (Tic)
The contractual specification should define a regulation curve for the interior temperature setpoint (T ),
ic,0
the maximal range of the offset of T (T ) and its increment. The interior temperature setpoint is given
ic ic,Off
by Formula (6):
T = T + T (6)
ic ic,0 ic,Off
NOTE 1 For example the Tic,Off could be ± 2 K and the increment could be 0,5 K.
In the absence of such definition, the relevant curve shown in Figure B.1 and a T of 0 K shall be
ic,Off
adopted.
The mean interior temperature shall follow this regulation curve within the limits of capacity defined in
Clause 8. Outside these limits temperature deviation is allowed.
NOTE 2 With the capacity determined according to this document, the HVAC system is not always able to provide
a mean interior temperature (Tim) that reaches the interior temperature setpoint (Tic).
9.3 Interior temperature setpoint (Tic) for vehicles without cooling
The mean interior temperature shall meet interior temperature setpoint (T ) mentioned in 9.2 as long as
ic
the exterior conditions and / or internal loads enable this interior temperature to be achieved.
10 Comfort condition requirements
10.1 Requirements for comfort zone
10.1.1 Quality regulation for steady-state tests
10.1.1.1 Range of the mean interior temperature (T ) with the respect to the interior
im
temperature setpoint (T ) for steady-state tests (ΔT )
ic i
Within the performance limits defined in 8.2 and 8.4, the difference ΔT between the mean interior
i
temperature (T ) and interior temperature setpoint (T ) shall remain within the range of ± q (refer to
im ic i
key 4 of Figure 9). The values of q are defined in Table 7.
i
In case T is not reaching T due to the performance limits defined in 8.2 and 8.4, the weighting factor
im ic
used for this comfort parameter is set to 0 (zero) in the calculation of comfort level (refer to normative
Annex O).
Table
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