EN 15757-2010 en Conservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic material.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 15757:2010Conservation of CulturalProperty Specificationsfor temperature and relativehumidity to limit climate-induced mechanical damage inorganic hygroscopic materialsBS E

2、N 15757:2010 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 15757:2010.The UK participation in its preparation was entrusted to TechnicalCommittee B/560, Conservation of tangible cultural heritage.A list of organizations represented on this committee can beobta

3、ined on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 60906 0ICS 97.195Compliance with a British Standard cannot confer immunity fromlegal obligations.This Brit

4、ish Standard was published under the authority of theStandards Policy and Strategy Committee on 30 September 2010.Amendments issued since publicationDate Text affectedBS EN 15757:2010EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15757 September 2010 ICS 97.195 English Version Conservation of

5、Cultural Property - Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials Conservation des biens culturels - Spcifications applicables la temprature et lhumidit relative pour limiter les dommages mcaniques causs par le climat

6、 aux matriaux organiques hygroscopiques Erhaltung des kulturellen Erbes - Festlegungen fr Temperatur und relative Luftfeuchte zur Begrenzung klimabedingter mechanischer Beschdigungen an organischen hygroskopischen Materialien This European Standard was approved by CEN on 30 July 2010. CEN members ar

7、e 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

8、the CEN 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 Management Centre has the sam

9、e 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, Po

10、rtugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2010 CEN All rights of exploitation in any form and by any mea

11、ns reserved worldwide for CEN national Members. Ref. No. EN 15757:2010: EBS EN 15757:2010EN 15757:2010 (E) 2 Contents Page Foreword 3Introduction .41 Scope 62 Normative references 63 Terms and definitions .64 General recommendations for organic hygroscopic materials 75 Approach to specifying tempera

12、ture and RH for organic hygroscopic materials 85.1 Determination of priorities 85.2 Maintaining stable environmental conditions 85.3 Priority of historical climate .95.4 Further specifications .9Annex A (informative) Determination of the RH targets . 10A.1 Rationale 10A.2 Environmental monitoring da

13、ta set . 10A.3 Calculation of the target values 10A.3.1 Average level . 10A.3.2 Seasonal cycle 10A.3.3 Short-term fluctuations 11A.4 Determination of the target range . 11A.5 Example . 11Bibliography . 14BS EN 15757:2010EN 15757:2010 (E) 3 Foreword This document (EN 15757:2010) has been prepared by

14、Technical Committee CEN/TC 346 “Conservation of Cultural Property”, the secretariat of which is held by UNI. 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 March 2011, and conflicting national st

15、andards shall be withdrawn at the latest by March 2011. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC I

16、nternal Regulations, the national standards organizations 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, Lu

17、xembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15757:2010EN 15757:2010 (E) 4 Introduction This European Standard is a guide specifying temperature and relative humidity (RH) to preserve cultural property b

18、y limiting physical damage induced by strain-stress cycles in objects containing organic hygroscopic materials. This category of objects includes wooden items and structural elements such as floors, doors, panelling and roof timbers, paintings, books, graphic documents, textiles, objects made of bon

19、e, ivory or leather. Objects can consist of several hygroscopic materials and different kinds of materials can be used together. To a varying degree, they are vulnerable to changes and fluctuations in ambient RH that produce changes in equilibrium moisture content (EMC) in the materials as they adso

20、rb and release moisture to adapt themselves to the continually changing environmental conditions. The variations in EMC produce dimensional changes of the materials which may lead to high levels of stress and physical damage such as fracture and deformation. Objects containing organic hygroscopic ma

21、terials need individually determined levels and ranges of temperature and RH as generally they have become acclimatised to the environments in which they have been exposed for significant periods of time. Over time, as temperature and RH fluctuations cause sufficient internal stress to create fractu

22、res, these fractures will open and close as expansion joints enabling a wider range of acceptable temperature and RH fluctuations. The material is said to have “acclimatised“ as it now responds differently to atmospheric conditions, though this acclimatisation should not be given a positive connotat

23、ion because it is due to internal fracturing and results in a form of damage. The associated loss of historical value, aesthetic value and also monetary depends on the size and location of the crack. The determination of the temperature and RH ranges, which are optimal for preservation, is not simpl

24、e due to the variety and complexity of the materials the objects comprise. Temperature has a direct effect on preservation but also an indirect effect as it controls RH of the air. The changes and fluctuations in temperature and RH should be considered from a static point of view of allowable levels

25、 or ranges and from a dynamic point of view, i.e. rate of change, duration of cycles and frequency at which cycles are repeated should be taken into account. Deterioration is often of a cumulative nature and may be exacerbated by the number and the intensity of the individual environmental hazards.

26、Changes and fluctuations of temperature and RH cause non-recoverable physical changes in materials although this is not always perceptible to the human eye. Vulnerability to deterioration mechanisms may increase with ageing. The same temperature and RH fluctuations may generate different effects dep

27、ending on the type of object and its age. Given the extreme complexity of the response of materials found in cultural property to variations of temperature and RH, this standard proposes a methodology leading to general specifications to limit climate-induced physical damage of organic hygroscopic m

28、aterials. Therefore the standard deals with a selected category of damage and does not cover other important deterioration processes affecting other materials influenced by microclimatic factors such as oxidation, acid hydrolysis, biodeterioration, corrosion reactions and dissolution of associated m

29、aterials due to deliquescence, salt crystallisation among others. The proposed methodology is based on an analysis of a particular historical climate environment and a condition survey of the most vulnerable and/or valuable objects. The decision therefore is made on the harmlessness (or otherwise) o

30、f the existing climatic conditions. This approach usually allows for target temperatures and RH ranges that are more flexible than the single target values that are commonly accepted as ideal conditions for preservation of cultural property. This in turns allows a reduction in the environmental cont

31、rol needed to ensure good preservation of objects. Less and simpler equipment is required and investment, maintenance costs can be reduced. The control of temperature and RH can be further minimised by enhancing the passive control capacity of the building. High standards of preservation in historic

32、al buildings can be maintained through the use of affordable and efficient low energy solutions despite increase in the cost of energy. BS EN 15757:2010EN 15757:2010 (E) 5 Any change affecting (or concerning) the environment of an object or a collection have to be decided upon by a team of relevant

33、professionals, which always includes a suitably qualified conservator, experienced in assessing the condition of collections and an expert in environmental control. BS EN 15757:2010EN 15757:2010 (E) 6 1 Scope This European Standard is a guide specifying temperature and relative humidity levels to li

34、mit climate-induced physical damage of hygroscopic, organic materials, kept in long-term storage or exhibition (more than one per year) in indoor environments of museums, galleries, storage areas, archives, libraries, churches and modern or historical buildings. 2 Normative references The following

35、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. prEN 15898:2010, Conservation of cultural property Main general

36、 terms and definitions concerning conservation of cultural property 3 Terms and definitions For the purposes of this document, the terms and definitions given in prEN 15898:2010 and the following apply. 3.1 active control use of devices able to force exchanges of heat, moisture or air, integrated wi

37、th real-time processing sensors and controllers 3.2 air temperature T temperature read on a thermometer which is exposed to air in a position sheltered from direct solar radiation or other energy sources NOTE If objects are exposed to direct radiation black globe or black strip thermometers should b

38、e used. For definition see also EN 15758. 3.3 equilibrium moisture content EMC moisture content at which a hygroscopic material neither loses nor gains moisture from the surrounding atmosphere at given relative humidity and temperature levels 3.4 Heating, Ventilating or Air Conditioning Systems HVAC

39、 active systems operated to control air temperature (heating), air temperature and humidity (air conditioning), or ventilation in a building 3.5 historical climate climatic conditions in a microenvironment where a cultural heritage object has always been kept, or has been kept for a long period of t

40、ime (at least one year) and to which it has become acclimatized BS EN 15757:2010EN 15757:2010 (E) 7 3.6 hygroscopic material material which adsorbs moisture when the environmental relative humidity rises, and loses moisture when relative humidity drops 3.7 indoor environment area within a building w

41、here cultural heritage objects are preserved 3.8 microclimate climate on a small spatial scale NOTE Typically refers to the microenvironment that interacts with the objects under consideration. 3.9 Relative Humidity RH ratio of the actual water vapour pressure to the saturation vapour pressure 3.10

42、target level RH level that should be maintained to best ensure preservation NOTE Determined by the historical climate of a given environment that has been proved not to be harmful to the preservation of objects. Otherwise, it should be specified by a qualified conservation professional. 3.11 target

43、range range of RH fluctuations that should be not be exceeded to best ensure preservation NOTE Determined by the historical climate of a given environment that has been proved not to be harmful to the preservation of objects. Otherwise, it should be specified by a qualified conservation professional

44、. 4 General recommendations for organic hygroscopic materials In general, organic hygroscopic materials require a mid RH range as the extremes (high and low RH ranges), affecting the EMC, can result in structural damage, deformation and cracking. However, a material that has been stored for signific

45、ant periods of time even in a poor quality environment will have become acclimatised to the conditions. Careful analysis of the materials needs is required to ensure that specified standard levels do not generate further damage. Any change from a particular historical climatic environment may be pro

46、blematic, even though the new conditions appear better for long-term preservation. If the change is sudden, the strain-stress may generate a climatic shock leading to more intense levels of damage. Even if the change is slow, it may still generate stress and result in damage. Therefore, the strategy

47、 of this standard focuses on maintaining the microclimate in terms of levels, seasonal cycles and fluctuations of temperature and RH, to which the materials have become acclimatized for a long time if this microclimate has been proved not to be harmful. Before a decision is made on the harmfulness o

48、r otherwise of pre-existing climatic conditions, the professional conservator involved in the project should carry out a condition report on the most vulnerable and/or valuable objects to be subjected to any environmental control proposal. If the material has to be moved to a different climatic envi

49、ronment, then a careful, frequent monitoring of the condition of the material is necessary to detect symptoms of deterioration allowing stabilisation of environmental conditions which are appropriate for the needs of the materials. BS EN 15757:2010EN 15757:2010 (E) 8 When dealing with composite objects or when objects made of different materials occupy the same location, an evaluation of potential interaction between materials or parts of objects made of similar materials is necessary, as this situation is more complex