English Version. Aerospace series - Aircraft integrated air quality and pressure standards, criteria and determination methods

Transcription

1 EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM DRAFT pren 4666 February 2013 ICS English Version Aerospace series - Aircraft integrated air quality and pressure standards, criteria and determination methods Série aérospatiale - Normes intégrées de qualité d'air intérieur et de pression pour les cabines d'avion, critères et méthodes d'évaluation Luft- und Raumfahrt - Integrierte Qualitätsstandards für Kabinenluft und -druck, Kriterien und Messverfahren This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee ASD-STAN. If this draft becomes a European Standard, 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. This draft European Standard was established by CEN 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom. Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are aware and to provide supporting documentation. Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and shall not be referred to as a European Standard. EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2013 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. : E

2 Contents Page Foreword... 4 Introduction Scope Normative References Terms and definitions Abbreviations Pressure Conditions General Rates of Change of Cabin Air Pressure Absolute Cabin Air Pressure General Physiological Altitude Limits DVT recommendation Ventilation Thermal Conditions Cabin air temperature General Requirements and rationale Surface temperature General Requirements and rationale Local Airflow General Requirements and rationale Humidity Conditions Relative Humidity Requirements and rationale Measurement method Noise and Vibration Noise Vibration Vibration Requirements and rationales Combined Effects General Temperature & Humidity Temperature & Noise Humidity & Noise Perceived Air Quality & Enthalpy Generic Analysis of Combined Effects Annex A (informative) The Decitherm-Approach A.1 General A.2 Scale of operative temperature thermal levels A.2.1 General A.2.2 Optimal operative temperatures A.2.3 Long-term tolerable operative temperatures A.2.4 Short-term tolerable operative temperatures A.2.5 Intolerable operative temperatures A.3 Application to optimal operative temperatures in an airliner cabin Annex B (informative) Example of a Complex Model for Generic Analyses of Combined Effects B.1 General B.2 Low pressure and high air velocity condition

3 B.3 Low pressure and cool temperature condition B.4 Conclusions for combined effects Annex C (informative) Example of Interrelations of Comfort Parameters Bibliography

4 Foreword This document () has been prepared by the Aerospace and Defence Industries Association of Europe - Standardization (ASD-STAN). After enquiries and votes carried out in accordance with the rules of this Association, this Standard has received the approval of the National Associations and the Official Services of the member countries of ASD, prior to its presentation to CEN. This document is currently submitted to the CEN Enquiry. This standard was reviewed by the Domain Technical Coordinator of ASD-STAN's Engineering Procedures Domain. After inquiries and votes carried out in accordance with the rules of ASD-STAN defined in ASD-STAN's General Process Manual, this standard has received approval for Publication. This European standard has been prepared by a Working Group of ICE. ICE is an EU 6 th framework project within the Competitive and Sustainable Growth Programme, Key Action: New Perspectives in Aeronautics. The secretariat of the working group is held by BRE, UK in cooperation with Fraunhofer IBP, Germany. The working group was set up in conjunction with ASD-STAN. ASD-STAN is a CEN Associated Body, which produces standards for aviation and defence. ASD-STAN rules have been followed during the drafting of the standard, and CEN procedures have been carried out to approve the standard. In 2004, AECMA-STAN published the first pre-standard (pren 4618) including both contamination threshold limits and environmental criteria for aircraft cabins. It is now a full standard (EN 4618). In 2007, the American Society of Heating, Refrigerating, and Air Conditioning Engineers (ASHRAE) published a comprehensive aircraft air quality standard: Standard Air quality within commercial aircraft. However, this did not include cabin pressure (paragraph of the ASHRAE Standard). PrEN 4666 is the first Standard to include cabin pressure. This pren 4666 however is a self-standing standard, independent from EN 4618 or any other similar subject document. Disclaimer: All recommendations made here are based on the European study ICE - Ideal Cabin Environment (European Contract No. AST4-CT ) and on related findings. All final responsibility for flight operations and handling of aircraft remain with the airlines, manufacturers and their employees as well as the relevant authorities. Introduction This European Standard has been prepared in order to specify requirements and determination methods for newly certificated commercial civil passenger aircraft programmes. It may also apply to current production aircraft, should it be shown to be technically feasible and economically justifiable. The standard distinguishes between safety, health and comfort conditions for passengers and crew under a variety of phases of flight, including embarkation and disembarkation. The standard is intended for use in design, manufacturing, maintenance and normal operation of commercial aircraft. The standard committee has tried to make the standard performance based. This means that only parameters of direct effect on safety, health and comfort of aircraft occupants are considered. This approach enables future proofing of design and development of innovative solutions as well as enabling existing technologies to be used. Nevertheless, in exceptional cases, current technology may be used in notes, 4

5 appendices and/or recommendations to describe available solutions that meet the objectives of individual requirements of the standard. This is a performance standard focussing on achievements, not a prescriptive standard driving specific technical solutions. This European Standard or parts thereof may be applied by regulatory bodies. The study on which this European Standard is based was conducted in compliance with: - International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (1996) Guideline for Good Clinical Practice E6 (R1) - Directive 91/507/EEC (19 July 1991) modifying the Annex to Council Directive 75/318/EEC on the approximation of the laws of Member States relating to analytical, pharmacotoxicological and clinical standards and protocols in respect of the testing of medicinal products - Directive 2001/20/EC of the European Parliament and of the Council (4 April 2001) on the approximation of the laws, regulations and administrative provisions of the Member States relating to the implementation of good clinical practice in the conduct of clinical trials on medicinal products for human use - Directive 2003/10/EC of the European Parliament and of the Council (6 February 2003)on the minimum health and safety requirements regarding the exposure of workers to the risks arising from physical agents (noise) - WHO (1999) Guidelines for Community Noise. - WHO (2001) Occupational and Community Noise. Fact Sheet No

6 1 Scope This European Standard specifies requirements and determination methods for newly certificated commercial civil passenger aircraft programmes regarding integrated air quality parameters and cabin air pressure. This European Standard is intended to apply to newly certificated commercial civil passenger aircraft programmes. It may also apply to current production aircraft if it does not carry significant burden, i.e. if it can be shown to be technically feasible and economically justifiable. This European Standard covers the period for each flight when the first crewmember enters the aircraft until the disembarkation of the last crewmember. NOTE 1 During embarkation and disembarkation, reduced temperatures in the cabin may be desirable due to increased metabolic activity of the occupants. In some ground cases, the aircraft environmental control system (ECS) may not be able to compensate for the external conditions influencing the cabin comfort conditions, such as open doors, extreme hot/cold ground/air temperatures or radiant heat. In this case, external air-conditioning systems, for example conditioned low-pressure ground air or high-pressure supply, may be used to supplement the aircraft ECS. If the temperature range stated in this European Standard is regularly exceeded (either above or below the stated range), changes to airline and/or airport procedures and/or aircraft design should be introduced. NOTE 2 During ground operations, the external air quality may adversely influence the air quality within the aircraft cabin. Contamination produced as a result of servicing activities or ground operations may enter the aircraft directly, for example via open doors, and the ECS may not be able to effectively control contaminant levels in the cabin. Airline and airport operational procedures should be organised so as to avoid direct contamination of the cabin from these pollutant sources. If the contaminant ranges stated in this European Standard are regularly exceeded, changes to airline and/or airport procedures and/or aircraft design should be introduced. Outside air quality levels would usually be regulated by national authorities. Individual predisposition may influence the proposed values and limits. pren 4666 is a self-standing standard, independent from EN 4618 or any other similar subject documents. This European Standard covers data for: - Pressure Conditions (air pressure rate of change, absolute cabin air pressure) - Thermal Conditions (air temperature, surface temperature, draught) - Humidity Conditions - Noise and Vibration - Combined Effects as newly developed by the European study ICE - Ideal Cabin Environment (European Contract No. AST4- CT ) and its related findings. 6

7 2 Normative References The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ASHRAE Standard 62.2 (2007) Ventilation and Acceptable Indoor Air Quality in Low-Rise Residential Buildings ASHRAE Standard 161 (2007) Air Quality within Commercial Aircraft CFR 14 Part (1997) Ventilation and Heating EN 4618 (2009) Aircraft internal air quality standards, criteria and determination methods ISO (1997) Mechanical Vibration and Shock - Evaluation of Human Exposure to Whole-Body Vibration -- Part 1: General Requirements ISO 5129 (2001) Acoustics -- Measurement of sound pressure levels in the interior of aircraft during flight ISO (2007) Ergonomics of the thermal environment -- Determination and interpretation of cold stress when using required clothing insulation (IREQ) and local cooling effects ISO (2006) Ergonomics of the thermal environment -- Methods for the assessment of human responses to contact with surfaces -- Part 1: Hot surfaces ISO/TS (2001) 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 (2005) Ergonomics of the thermal environment -- Methods for the assessment of human responses to contact with surfaces -- Part 3: Cold surfaces ISO 7726 (1998) Ergonomics of the thermal environment -- Instruments for measuring physical quantities ISO 7730 (2005) 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 SAE AIR1609A (2005) Aircraft Humidification SAE ARP1270 (2006) Aircraft Cabin Pressurization Control Criteria UK CAA Specification No. 15 (1989) Public Address Systems 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 safety limits limits for cabin environment parameters that if exceeded would prevent the safe operation of the aircraft. Where appropriate, limits such as occupational exposure limits and regulatory limits are taken from cognisant authorities [SOURCE: EN 4618:2009] 3.2 health limits limits for cabin environment parameters that if exceeded would lead to temporary or permanent pathological effects to the occupants. Where appropriate, limits such as occupational exposure limits and regulatory limits are taken from cognisant authorities [SOURCE: EN 4618:2009] 7

8 3.3 comfort limits limits for cabin environment parameters that if exceeded would not achieve an acceptable cabin environment. An acceptable cabin environment is defined as one in which a substantial majority of the people exposed would not be expected to express dissatisfaction with the air quality contaminants and/or environmental criteria. Where appropriate, comfort limits are drawn from cognisant authorities that provide indoor environment standards and guidelines [SOURCE: EN 4618:2009] 3.4 cabin pressurisation cabin pressurisation is the active pumping of air into an aircraft cabin to increase the air pressure within the cabin. It is required when an aircraft reaches high altitudes, because the natural atmospheric pressure (and in close sequence the oxygen partial pressure) is too low to allow people to absorb sufficient oxygen, leading to altitude sickness and ultimately hypoxia 3.5 cabin ventilation process of supplying air to or removing it from the cabin for the purpose of controlling air contaminant levels, cabin air pressure, humidity, airflow patterns, and temperature within the cabin 3.6 acceptable indoor air quality air toward which a substantial majority of occupants express no dissatisfaction with respect to odour and sensory irritation and in which there are not likely to be contaminants at concentrations that are known to pose a health risk [SOURCE: ASHRAE 62.2 (2007)] 8

9 4 Abbreviations ICE ECS CFR ASHRAE SAE CAA WHO Ideal Cabin Environment Environmental Control System Code of Federal Regulations American Society of Heating, Refrigerating, and Air-Conditioning Engineers Society of Automotive Engineers Civil Aviation Authority World Health Organization DVT PM PAO BF RH FACE HEACE SpO 2 deep venous thrombosis Particulate matter Personal Air Outlet Blink Frequency Relative Humidity Friendly Aircraft Cabin Environment Health Effects in Aircraft Cabin Environment oxygen saturation in peripheral blood flow 9

10 5 Pressure Conditions 5.1 General This Clause does not handle the matter of - any failure, like the unlikely loss of cabin air pressure - different oxygen breathing systems and oxygen equipment - the technical solutions of pressurisation and pressure vessel integrity - any test-procedures for pressurisation 5.2 Rates of Change of Cabin Air Pressure As the airplane pressurises and decompresses, some passengers may experience discomfort as gas trapped within body cavities expands or contracts in response to the changing cabin air pressure. The most common problems occur with gas trapped in the gastrointestinal tract, the middle ear and the paranasal sinuses. Note that in a pressurised aircraft these effects are not due directly to ascent and descent, but to changes in the air pressure inside the aircraft. The rate of change of cabin altitude should be limited to 2.5 m/s (500 ft/min) [sea level equivalent] for decreasing air pressure (increasing altitude) 1.5 m/s (300 ft/min) [sea level equivalent] for increasing air pressure (decreasing altitude) [SAE ARP1270 (2001), ASHRAE Standard 161 (2007)]. These guidelines are based on the middle ear ventilation and were followed during the conduct of the ICE study. The rate of change of cabin air pressure should be - as low as possible - as constant as possible during climb or descent 5.3 Absolute Cabin Air Pressure General Pressurised cabins and compartments to be occupied currently must be equipped to provide a cabin air pressure altitude of not more than 2438 m (8000 ft, 10.9 psi, 75 kpa) at the maximum operating altitude of the aeroplane under normal operating conditions Physiological Altitude Limits In considering the appropriate cabin altitude for a commercial passenger aircraft, the needs of three distinct groups must be taken into account: The safety, health and comfort of passengers a. Young, fit and healthy b. Elderly but without known medical conditions c. Those with known medical conditions. 2. The ability of pilots to perform both normal and abnormal operations, including on long-duration flights 3. The ability of the cabin crew to perform normal duties, including moderate exercise, and emergency procedures involving significant exertion. At higher altitudes the partial pressure of oxygen is reduced in comparison to that at ground level. This results in a reduction in blood haemoglobin oxygen saturation with increasing altitude. The structure of the haemoglobin molecule gives rise to the sigmoid shape of the oxyhaemoglobin dissociation curve showing that oxygen saturation does not fall below 90% until the altitude exceeds ft. In order to ensure adequate oxygen delivery to the tissues the human body responds by a slight increase in pulse rate and a

11 small increase in respiratory rate, but in a healthy individual this only occurs above about 8000 ft. There is no discernible change below this altitude. The ability of the cardiovascular system to compensate in a mild hypoxic environment may be compromised by both age and disease. The tension of oxygen in the arteries is lower than that in the lung alveoli, with a gradient of approximately 8 mmhg in young healthy individuals, increasing gradually with age and markedly elevated with cardiopulmonary disease. The changes in respiratory mechanics with age and disease can induce a greater ventilation/perfusion mismatch, but the body s homeostatic mechanisms lead to a compensatory increase in pulse and breathing rate such that persons respond without any discernible discomfort nor adverse health effects. The [British Thoracic Society (2002)] and the [Aerospace Medical Association (2003)] publish guidelines for the use of supplementary oxygen by air travellers suffering from cardio-respiratory impairment, which may be necessary at any altitude above mean sea level. Each case requires individual assessment, and it is not possible to define a safe maximum cabin altitude which is applicable to all or the majority of elderly or cardiorespiratory compromised passengers. Studies of pilots [Cottrell et al. (1995)] have shown wide individual variations in arterial oxygen saturation levels, levels varying between 88.6% and 97.0% during cruise up to 8000 ft, with large individual differences. It has been shown that mild hypoxia impairs performance of complex tasks in the learning phase, but has less effect if the task is well learned or has been practised [Denison et al. (1996)]. The role of cabin crew differs significantly from that of cockpit crew, with increased physical activities. Research has shown that many of the specific tasks occur for a relatively brief period of time and require strength as opposed to cardiovascular fitness. In-flight measurements have shown that no undue cardiovascular stress was imposed by routine tasks [Wilson et al. (2005)]. No measurements were made during emergency situations such as opening cabin doors, deploying emergency slides and facilitating cabin evacuation. However, by definition these emergency activities would occur at ground level. The concepts of comfort and well-being mean different things to different people. Well-being refers to the interaction between physical, psychological and emotional factors and is a satisfactory state of mind. Psychosocial and environmental determinants of human behaviour can have a variable influence on wellbeing. The Aerospace Medical Association [Thibeault (1997)] has shown that the question of well-being during a flight is the result of a wide range of physical effects including noise, vibration, acceleration, motion, heating, lighting, seat comfort, etc, as well as the hypobaric environment. The inter-relationship of these factors can be complex and must be considered together. The Aviation Safety Committee of the Aerospace Medical Association concluded in 2008 [Aerospace Medical Association (2008)] that there is insufficient evidence to recommend a change in the existing rules or practice governing maximum design or operational cabin altitude, which is congruent with the data from the ICE study [ICE consortium (2009)] DVT recommendation There is evidence that the immobility associated with the sedentary posture adopted during travel may encourage the development of deep venous thrombosis (DVT) and the potentially fatal consequence of pulmonary embolism [Cannegieter et al. (2006)]. This European Standard therefore recommends compliance with current medical opinion. Persons known to be at particular risk of venous thrombosis should take precautions under medical advice. Fluid retention in the legs can be avoided by activation of the leg muscle pumps through appropriate leg exercises. Persons with venous incompetence affecting the legs may be helped by correctly fitted elastic support stockings. Fluid intake, alcohol consumption and smoking are already subject to advice relevant to general health. For the normal travelling public no specific DVT advice is necessary. 11

12 6 Ventilation Cabin ventilation has to be sufficient to provide oxygen for breathing purposes and provide appropriate air quality achieving dilution of contaminants 12

13 7 Thermal Conditions 7.1 Cabin air temperature General Cabin air temperature is the temperature to which cabin occupants are exposed to during flight Requirements and rationale Level Limits Rationale Safety Upper limits as defined in [CFR 14 Ch. I (1996)]: t a < 60 C at any time t a = 60 C for max. 10 min 60 C > t a > 38 C see line graph in [CFR 14 Ch. I g (1996)] t a = 38 C for max. 90 min There are no lower safety limits defined. Health 19 C < t a < 34 C 2 Comfort 21 C < t a < 25 C while 20 C < t a,01 < 25 C t a = t a,11 t a,01 < 3 K t a ambient temperature t a,01 ambient temperature at ankle height (0.1 m) t a,11 ambient temperature at head height (1.1 m) Rationale: 1 Limits defined by [CFR 14 Ch. I (1996)]. 2 Temperature limits 19 C < t a < 34 C correspond to -45 dth < L th < 90 dth. 3 Temperature limits 21 C < t a < 25 C correspond to -20 dth < L th < 20 dth. If air temperatures at ankle height fall below 20 C or its difference to the air temperatures at head height is larger than 3 K local thermal discomfort dominates overall thermal comfort. Decitherm is the thermal level informing about environment impact on human body for supposed optimal temperature 23 C. For an activity of 1.2 met and clothing of 0.75 clo the thermal level is L th = lg(t a /23) The following table gives the corresponding thermal levels to prescribed temperatures for warm and cold environments. Corresponding thermal levels Temperature Very pleasant 21 C < t a < 25 C Pleasant 20 C < t a < 26 C Acceptable 19 C < t a < 28 C Long-term tolerable - cold conditions: t < 20 min [ISO (2007)] 19 C < t - warm conditions: t < 480 min a < 34 C [Jokl et al. (1997), Kabele and Dvořáková (2007)] Short-term tolerable - cold conditions: t < 20 min [ISO (2007)] - warm conditions: t < 50 min [Jokl et al. (1997)] Intolerable With activity of 1.2 met and clothing of 0.75 clo For a detailed description of the decitherm approach refer to Annex A. 13 C < t a < 42 C t a < 13 C or t a > 42 C Measurement methods are described in [ISO 7726 (1998)] and should cover a temperature range of 0 C to 70 C at a resolution of 0.1 K with an accuracy of +/- 0.2 K and a response time of < 10 s. Requirements are

14 applicable to the temperature profile of a seat at ankle height (approx. 0.1 m), knee height (approx. 0.6 m) and head height (approx. 1.1 m) Surface temperature General Surface temperatures refer to those surfaces which are relatively close to seated passengers and may be touched by the passenger for longer durations: floor, side walls, overhead bins, seating area Requirements and rationale Level Limits Rationale Safety No specific safety limits 1 Health Minimum contact temperature t c addressed through ISO :2006: t c,min = 7 C Maximum surface temperatures t s addressed through ISO :2006: t s,max = 48 C for contact durations less than 10 min t s,max = 43 C for contact durations less than 8 h Comfort Minimum contact temperature t c addressed through ISO :2006: t c,min = 15 C Maximum surface temperature t s addressed through ISO/TS :2001 t s,max = 40 C t c contact temperature t s surface temperature Rationale: 1 No specific safety limits defined. 2 If the contact temperature of skin with cold surfaces falls below 7 C numbness may occur. These contact temperatures are dependent on the material touched and contact duration. Guidance is provided in ISO :2006, see also Geng et al. (2006). If hot surfaces of 48 C are touched 10 min skin burning may occur, for contact durations > 8 h surface temperatures of 43 C may yield to skin burning regardless of the surface material (ISO :2006). 3 Contact temperatures between materials and skin may be perceived as painful below 15 C (ISO :2006, see also Geng et al. (2006)). To avoid discomfort through radiant asymmetry average surface temperatures above 18 C are recommended. Temperatures of surfaces touched by skin may be perceived as painful above 40 C and are considered as moderate below 40 C (ISO/TS :2001). To avoid discomfort through radiant asymmetry average surface temperatures below 28 C are recommended. 2 3 Measurement methods are described in [ISO 7726 (1998)] and should cover a temperature range of 0 C to 70 C at a resolution of 0,1 K with an accuracy of +/- 0,2 K and a response time of < 10 s. Requirements are applicable to the temperature profile of a seat at ankle height (approx. 0.1 cm), knee height (approx. 0.6 m) and head height (approx. 1.1 m). 14

15 7.3 Local Airflow General Personal Air Outlets (PAOs) are optional and therefore excluded from the standard Requirements and rationale Level Limits Rationale Safety No specific safety limits 1 Health No specific health limits 2 Comfort v a < 0.2 m/s at draft sensitive bare body parts: ankles (0.1 m) and neck (1.1 m) v a < 0.36 m/s otherwise as addressed through [ASHRAE standard 161 (2007)] v a air velocity Rationale: 1 No specific safety limits available for expected aircraft operational air velocities. 2 No specific health limits available for expected aircraft operational air velocities. However, the increase of the blink frequency (BF) may lead to additional discomfort in form of eye (lid) fatigue. It may enhance musculoskeletal tiredness and overloading of the eye (i.e. asthenopia). High air velocity (> 1 m/s) may result in a slight increase of BF during resting conditions. High horizontal or downward air velocity along the head region enhances the evaporation of water by disappearance of the stagnant (boundary) layer around the ocular region. This accelerates a temperature decrease, especially in cornea and the blink frequency is partly triggered by a decrease of the cornea temperature (e.g., higher temperature lowers BF), see Wolkoff (2008). 3 The maximum value of air velocity averaged over a two-minute-period should not exceed the limits addressed through [ASHRAE standard 161 (2007)]. Occupant acceptability of a given air velocity will vary with supply air temperature. Measurement methods are described in [ISO 7726 (1998)]. Requirements are applicable to the air velocity profile of a seat at ankle height (approx. 0.1 cm), knee height (approx. 0.6 m) and head height (approx. 1.1 m). 3 15

16 8 Humidity Conditions 8.1 Relative Humidity Requirements and rationale Level Limits Rationale Safety No specific safety limits 1 Health No specific health limits 2 Comfort No specific comfort limits 3 Rationale: 1 This European Standard does not mandate minimum humidity levels due to the potential impact on safe aircraft operation [ASHRAE Standard 161 (2007)]. Levels of relative humidity should be within limits that guarantee a safe operation of the aircraft and its systems (no condensation, no corrosion, mechanical or electrical malfunctions). 2 There is currently no scientific proof of dependence of dryness related health issues on minimum levels of relative humidity. 3 The upper humidity levels imposed by safety during flight are lower than the lower limits warranted for occupant comfort; consequently, upper limits are not specified in This European Standard [ASHRAE Standard 161 (2007)]. However, within the range of comfortable cabin air temperature the ideal level of relative humidity would be 25 % to 30 % relative humidity and above since lower levels may cause discomfort (see Wyon et al. (2002), Sunwoo et al. (2006)). This is in line with the desired range of 30% to 60% for occupant comfort quoted in SAE AIR1609A (2005). Nonetheless, several studies found that mere perception of dryness in environments is not related to the physical measure of relative humidity (see e.g. Wyon et al (2002), Sundell and Lindvall (1993)). ICE test results suggest that there is a small improvement of dryness related symptoms such as dry eyes and dry skin if cabin humidity is increased from 10% to 40%. An increase from 10% to 25% agrees with this trend, but the difference is smaller. Based on these results there is no clear-cut threshold value for comfortable humidity levels inside aircraft cabins Measurement method The measurement methods and the measurement apparatus used to determine relative humidity should comply with the standard [ISO 7726 (1998)]. Concerning the particular case of the aircraft cabin environment, specific requirements and measurement locations are defined. The absolute air pressure has to be considered appropriately. Range Resolution Accuracy Response time Measurement location 0 % RH to 99 % RH 0.1 % RH ± 0.1 % RH (10 % RH to 90 % RH) ± 0.2 % RH (remaining range) < 20 s Measurements 1.1 m from floor in the centre of the front, mid and rear third of each zone. 16

17 9 Noise and Vibration 9.1 Noise Level Limits Rationale Safety Addressed through UK CAA Specification No. 15 (1989) 1 Health Addressed through Directive 2003/10/EC 2 Comfort No limit recommended 3 Rationale 1 UK CAA Specification No 15 (1989) prescribes minimum performance standards for intelligibility of safety-related announcements via the public address system of the aircraft. Intelligibility can be demonstrated by measurement of either Articulation Index (AI) or Rapid Speech Transmission Index (RASTI) under various flight conditions and at different locations in the cabin. 2 The Directive 2003/10/EC specifies exposure limit levels for workers. Obviously, this also does protect passengers. 3 No comfort limit or range could be established because there is a wide variation in the results of different studies. When comparing results from different research projects such as FACE, HEACE and also ASHRAE publications [Buss et al. (2005), Pierce et al. (1999), Weber et al. (2004)] it appeared that rated discomfort numbers or average comfort ratings were different. Equivalent noise levels seem to be rated more comfortable in real aircraft than in cabin simulators. Simulator tests differ from real flight tests at least because of missing outside view simulation, aircraft movement, missing in-flight entertainment (IFE) and passenger expectations. As a conclusion specific results are representative for the simulator being used, but not necessarily for aircraft. Also from automotive industry it is known that the same noise level is perceived higher than in the real environment, where the noise can be associated with the origin of the noise by experience. Additional studies would be required to establish the link between real flight tests and a simulated test environment accurately. However, lower noise levels were perceived more comfortable in general. Measurement Method ISO 5129 (2001) defines the measurement of sound pressure levels in the interior of aircraft during flight. 9.2 Vibration Effects of vibration on the human body are complex. Vibration may impair visual acuity, interfere with neuromuscular control including speech, and lead to fatigue. Mechanical impedance of the human body is dependent on the frequency of vibration, but not a linear relationship above 2 Hz due to body resonance. Resonance peaks occur at 3-4 Hz and Hz as a result of the body structure [Stott (2006)] [Directive 2002/44/EC]. 17

18 9.3 Vibration Requirements and rationales Level Limits Rationale Safety No specific value defined 1 Health L ex,8h = 1,15 m/s² (whole-body vibration) as addressed through Directive 2002/44/EC and ISO (1997), Annex B Comfort Rationale L ex < m/s² approximate indication for permanent exposure) as addressed through ISO (1997), Annex C Vibrations might affect safe operation of aircraft in different ways, which have to be evaluated and respected separately during the design of the aircraft, its systems and the human machine interfaces. Structural integrity and performance of aircraft and aircraft systems have to be verified for vibrations during normal and abnormal operating conditions. In addition the safe operation of the aircraft by the responsible crew has to be taken care of allowing for vibration impact on crew and aircraft systems (e.g. legibility of displays, handling of control instruments, physical distress etc). Therefore no universal limit can be defined. 2 The Directive 2002/44/EC specifies exposure limit levels for workers averaged over a normal 8h working day to be L ex,8h = 1,15 m/s² (whole-body vibration). Obviously, this also does protect passengers. ISO (1997) Annex B.3.1 indicates health guidance caution zones for different exposure durations. 3 Annex C.2.3 of ISO (1997) lists approximate indications of likely reactions to vibration environments: L ex Comfort Reaction < m/s² not uncomfortable m/s² to 0.63 m/s² a little uncomfortable 0.5 m/s² to 1 m/s² fairly uncomfortable 0.8 m/s² to 1.6 m/s² Uncomfortable m/s² to 2.5 m/s² very uncomfortable > 2 m/s² extremely uncomfortable Measurement Method ISO (1997) defines methods of quantifying whole-body vibrations in relation to a) human health and comfort, b) the probability of vibration perception and c) the incidence of motion sickness. 18

19 10 Combined Effects 10.1 General When changing one cabin parameter it has to be taken into account that it may have an influence on other parameters. Possible combined effects are discussed in sub-clauses below Temperature & Humidity There was no evidence of synergistic effects on comfort between temperature and relative humidity in the ICE study. For This European Standard the relative humidity at the levels demonstrated (10% to 40%) have no impact on thermal comfort votes in the tested temperature range (21 C to 25 C). Thus these parameters can be varied independently within these ranges Temperature & Noise Significant differences between thermal comfort votes at different background sound pressure levels (64 db(a) vs. 74 db(a)) were found by the ICE study [Grün et al. (2008)], see Annex C. This combined effect is in line with findings by [Clausen et al. (1993)], [Pellerin and Candas (2004)] and others Humidity & Noise There was no evidence of synergistic effects on comfort between background sound pressure levels and relative humidity in the ICE study. For This European Standard the relative humidity at the levels demonstrated (10% to 40%) have no impact in the tested range of background sound pressure levels (64 db(a) to 74 db(a)). Thus these parameters can be varied independently within these ranges Perceived Air Quality & Enthalpy Perceived Air Quality is affected by air enthalpy, which is a function of air pressure, temperature and humidity. The acceptability of indoor air and the influence of pollution on perceived air quality decreases with increasing enthalpy and thus increasing air temperature and humidity (see e.g. Fang et al. (1998)) Generic Analysis of Combined Effects The combination of more than one non-comfort conditions can have different effects on perceived comfort aspects. These effects may compensate or amplify each other. Analyses with complex models may help to identify these combined effects. Based on the ICE study such a complex model has been developed [Vankan et al. (2009)] and detailed analyses of this mathematical model show, that e.g. some effects at low pressure conditions may be slightly improved by changes in other conditions (see Annex B) 19

20 Annex A (informative) The Decitherm-Approach A.1 General The DeciTherm-approach is based on human body. The Decitherm-Approachphysiology where Weber- Fechner law is valid: R = k lg(s) (1) Where R the human body response S the stimulus of the environment causing the response k coefficient For the thermal state of the environment this law can be applied as [ref] Where [dth] (2) L th operative temperature thermal level [decitherm], [dth] T operative temperature [ C] T threshold threshold operative temperature, in this case the optimal operative temperature [ C] Equation (2) corresponds with the relationship for noise assessment, the acoustic pressure level [db] (3) where the stimulus is the ratio of acoustic pressures, P is the acoustic pressure within the space investigated; P 0 is the lower limit of perceived acoustic pressure 20 µpa. The unit for acoustic pressure level is the decibel (db) and it is proposed that for operative thermal level the unit is the decitherm (dth). A.2 Scale of operative temperature thermal levels A.2.1 General Thermal levels, analogically to operative temperatures, are optimal, tolerable and intolerable. Optimal values are very pleasant, pleasant and acceptable (optimal admissible from directives point of view). Tolerable are long-term and short-term tolerable. Corresponding thermal levels warm environments cool environments Very pleasant 0 dth to 20 dth 0 dth to -20 dth Pleasant 21 dth to 30 dth -21 dth to -30 dth Acceptable 31 dth to 45 dth -31 dth to -45 dth Long-term tolerable - cold conditions: t < 20 min [ISO (2007)] 46 dth to 90 dth Not permitted* - warm conditions: t < 480 min [Jokl et al. (1997), Kabele and Dvořáková (2007)] Short-term tolerable - cold conditions: t < 20 min [ISO (2007)] dth -46 dth to -134 dth - warm conditions: t < 50 min [Jokl et al. (1997)] Intolerable > 135 dth < -135 dth 20

21 A.2.2 Optimal operative temperatures Optimal operative temperatures (analogically as by noise and odors) correspond dth = 0 because lg(1) = 0. A.2.3 Long-term tolerable operative temperatures Long-term tolerable operative temperatures begin at the optimum upper limit and end at the operative temperature of average skin temperature level because at higher operative temperatures: there is the danger of human body hyperthermia with the body temperature increase. Range in dth: 46-90, see table. The long-term tolerable operative temperatures can be admitted in warm environment only: the disturbed thermal equilibrium is balanced by sweating. In cold environment sweating corresponds shivering which does not exist within most people (shivering caused by nerves cannot be taken into account). Thus shivering cannot be respected as a protective mechanism of the human body. Therefore only short-term values can be taken into account in cold environment. The durations for long-term operative temperatures for cold conditions can be estimated with t < 20 min [ISO (2007)] for warm conditions with t < 480 min [Jokl et al. (1997), Kabele and Dvořáková (2007)]. A.2.4 Short-term tolerable operative temperatures Short-term tolerable operative temperatures in warm environments begin with maximal long-term tolerable values, in cold environment with minimal values of optimum. The end in the warm is before the threshold of pain (ca. 42 C, 135dTh) (pain is the same criterion for noise). Range in dth: , see table. The durations for short-term operative temperatures for cold conditions can be estimated with t < 20 min [ISO (2007)] for warm conditions with t < 50 min [Jokl et al. (1997)]. The coefficient k th is determined by equation (2) applied for the maximum short-term tolerable operative temperature is: 135 k th = (4) 42 log Topt A.2.5 Intolerable operative temperatures Intolerable operative temperatures are characterized only by their beginning identical with the end of shortterm tolerable values. Range: 135dTh and more, see table. A.3 Application to optimal operative temperatures in an airliner cabin Optimal operative temperatures were estimated by the votes of subjects satisfied with the evaluated environment (or dissatisfied in the range 10% to 30% related to the requested environment quality). [dedear (1993), Fishman and Pimbert (1979)] Optimal operative temperature in an airliner cabin is T opt = 23 C (dth=0) [Jokl (2007), Jokl and Kabele (2007)]. Applying equations (2) and (4) the following expression is found for the decitherm level: L th = lg(t o /23) (5) The corresponding scale of operative temperature thermal levels for activity 1.2 Met and clothing 0.75 clo is presented below. The optimum operative temperature is between 21.0 C (-20dTh) and 25.1 C (20 dth). In the case of some failure the long-term tolerable values are closing at 34.4 C (90 dth). 21

22 Scale of operative temperature thermal levels for an airliner cabin with T opt = 23 C for activity 1.2 Met and clothing 0.75 warm environments cool environments Temperature clocorresponding thermal levels Very pleasant 0 dth to 20 dth 0 dth to -20 dth 21 C < t a < 25 C Pleasant 21 dth to 30 dth 20 C < t a < 26 C -21 dth to -30 dth Acceptable 31 dth to 45 dth 19 C < t a < 28 C -31 dth to -45 dth Long-term tolerable - cold conditions: t < 20 min [ISO (2007)] - warm conditions: t < 480 min [Jokl et al. (1997), Kabele and Dvořáková (2007)] 46 dth to 90 dth Not permitted 19 C < t a < 34 C Short-term tolerable - cold conditions: t < 20 min [ISO (2007)] dth -46 dth to -134 dth 13 C < t a < 42 C - warm conditions: t < 50 min [Jokl et al. (1997)] Intolerable > 135 dth < -135 dth t a < 13 C or t a > 42 C Figure A.1 - Scale of thermal levels for an airliner cabin (23 C). 22

23 Annex B (informative) Example of a Complex Model for Generic Analyses of Combined Effects B.1 General The model developed within the ICE project provide a representation of the dependencies of various physiological and psychological aspects of aircraft passengers on aircraft cabin conditions, flight characteristics and passenger characteristics, including behaviour. The software implementation of the models allows for quick computational evaluation of this representation. The mathematical model has been applied in several cases that assess the effects of the cabin conditions on the health and well-being of aircraft passengers. The combination of more than one non-comfort conditions can have different effects on an output variable. These effects may compensate or amplify each other. Exemplary cases have been selected for a detailed generic analysis. B.2 Low pressure and high air velocity condition From the results of previous sensitivity analyses it was hypothesized that some effects in the low pressure condition of the ICE study (ca. 753 hpa) may be compensated by the high air velocity condition (ca m/s). Therefore the combination of these two conditions has been evaluated. It is found that the predicted mean number of pain related symptoms in the low pressure condition indeed can be compensated by the high air velocity condition. In the combined condition the mean number of pain related symptoms is predicted about 5% lower than in the general mean comfort condition, whereas in the low pressure condition this number is about 15% higher than in the general mean comfort condition. The predicted mean thermal comfort vote however appears to get worse in the combined low pressure and high air velocity condition. In the combined condition the predicted mean thermal comfort vote is about 19% higher than in the general mean comfort condition, whereas in the low pressure condition it is about 15% higher than in the general mean comfort condition. There is no additional effect on predicted SpO 2 due to maximum air velocity, when combined with the low pressure condition, as could be expected. B.3 Low pressure and cool temperature condition In the combined low pressure and cool temperature condition (ca. 21 C), the predicted mean thermal comfort vote appears to switch to a decrease of 21% (lower than in the general mean comfort condition), instead of an increase for the low pressure condition of 15% (higher than in the general mean comfort condition). The predicted mean number of pain related symptoms in the low pressure condition can also be compensated by the cool temperature condition. In the combined condition this number is only about 5% higher than in the general mean comfort condition, whereas in the low pressure condition it is about 15% higher than in the general mean comfort condition. The predicted SpO 2 in the low pressure condition can also be slightly compensated by the cool temperature condition. In the combined condition it is about 27% lower than in the general mean comfort condition, whereas in the low pressure condition the predicted SpO 2 is about 36% lower than in the general mean comfort condition. B.4 Conclusions for combined effects From the considered cases of combined effects it can be concluded that some effects in the low pressure condition can be slightly improved by changes in other conditions. In particular the predicted SpO 2 increases from 91.8% in the low pressure condition to 92.7% in the combined low pressure and cool temperature condition. 23

24 The value for the predicted mean number of pain related symptoms also slightly improves, from 1.6 in the low pressure condition to 1.4 in the combined low pressure and cool temperature condition. However, besides these slight improvements there are also some other output variables that get worse in the combined low pressure and cool temperature condition. In particular the predicted mean number of reported headaches and of reported freezing increase from 1.1 to 1.3, and from 1.5 to 2.0, respectively. Figure B.1 - ICE combined effects: relative responses (in %) of all primary output variables evaluated with the model and resulting from some combinations of the above given variations of the input variables 24

25 Annex C (informative) Example of Interrelations of Comfort Parameters Example of impact of different levels of the environmental parameters pressure (P), air temperature (TA), relative humidity (RH) and sound pressure level (SPL) on the thermal comfort vote, as discussed in [Grün et al. (2008)] Figure C.1 Differences in comfort votes with respect to temperature between the answers after exposure of 6h and the pre-baseline. The labels indicate the environmental parameters during exposure, while they were constant during pre-baseline (TA = 22.9 C, P = 941 hpa, RH = 24.5%, SPL = 55.1 db(a)). = median = interquartile range. Significant differences between various tests are specified by brackets and the level of significance (with labeling a level < 0.01). 25

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