SIST EN 15757:2010
(Main)Conservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induces mechanical damage in organic hygroscopic materials
Conservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induces mechanical damage in organic hygroscopic materials
This European Standard is a guide specifying temperature and relative humidity levels to limit 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.
Erhaltung des kulturellen Erbes - Festlegungen für Temperatur und relative Luftfeuchte zur Begrenzung klimabedingter mechanischer Beschädigungen an organischen hygroskopischen Materialien
Diese Europäische Norm enthält allgemeine Festlegungen für die Temperatur und die relative Luftfeuchte mit dem Ziel, klimabedingte mechanische Beschädigungen zu begrenzen, die durch die Absorption von Feuchtigkeit an organischen Materialien auftreten können, insbesondere in Innenräumen von Museen, Galerien, Archiven, Bibliotheken, Kirchen sowie modernen oder historischen Gebäuden.
Conservation des biens culturels - Spécifications applicables à la température et à l'humidité relative pour limiter les dommages mécaniques causés par le climat aux matériaux organiques hygroscopiques
La présente Norme européenne fournit des spécifications générales applicables à la température et à l’humidité relative visant à limiter les dommages mécaniques causés par le climat aux matériaux organiques qui absorbent l’humidité, en particulier dans les milieux internes de musées, galeries, archives, bibliothèques, églises et bâtiments modernes ou historiques.
Ohranjanje kulturne dediščine - Specifikacije za temperaturo in relativno vlažnost za omejitev klimatsko pogojenih mehanskih poškodb organskih higroskopskih materialov
Ta evropski standard je vodilo, ki opredeljuje ravni temperatur in relativne vlažnosti za omejitev klimatsko pogojenih fizičnih poškodb organskih higroskopskih materialov, ki so v dolgoročnih skladiščih ali na razstavi (več kot eden na leto) v notranjih okoljih muzejev, galerij, skladiščnih prostorih, arhivih, knjižnicah, cerkvah in modernih ali zgodovinskih stavbah.
General Information
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.VNRSVNLKPDWHULDORYErhaltung des kulturellen Erbes - Festlegungen für Temperatur und relative Luftfeuchte zur Begrenzung klimabedingter mechanischer Beschädigungen an organischen hygroskopischen MaterialienConservation des biens culturels - Spécifications applicables à la température et à l'humidité relative pour limiter les dommages mécaniques causés par le climat aux matériaux organiques hygroscopiquesConservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induces mechanical damage in organic hygroscopic materials97.195Umetniški in obrtniški izdelkiItems of art and handicrafts17.200.01Termodinamika na splošnoThermodynamics in generalICS:Ta slovenski standard je istoveten z:EN 15757:2010SIST EN 15757:2010en,fr,de01-december-2010SIST EN 15757:2010SLOVENSKI
STANDARD
SIST EN 15757:2010
EUROPEAN STANDARD NORME EUROPÉENNE EUROPÄISCHE NORM
EN 15757
September 2010 ICS 97.195 English Version
Conservation of Cultural Property - Specifications for temperature and relative humidity to limit climate-induced mechanical damage in organic hygroscopic materials
Conservation des biens culturels - Spécifications applicables à la température et à l'humidité relative pour limiter les dommages mécaniques causés par le climat aux matériaux organiques hygroscopiques
Erhaltung des kulturellen Erbes - Festlegungen für Temperatur und relative Luftfeuchte zur Begrenzung klimabedingter mechanischer Beschädigungen an organischen hygroskopischen Materialien This European Standard was approved by CEN on 30 July 2010.
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 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 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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre:
Avenue Marnix 17,
B-1000 Brussels © 2010 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15757:2010: ESIST EN 15757:2010
EN 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 temperature 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 – data 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 . 14 SIST EN 15757:2010
EN 15757:2010 (E) 3 Foreword This document (EN 15757:2010) has been prepared by 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 standards 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 Internal 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, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. SIST EN 15757:2010
EN 15757:2010 (E) 4
Introduction This European Standard is a guide specifying temperature and relative humidity (RH) to preserve cultural property by 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 bone, 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 adsorb 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 materials 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 fractures, 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 connotation 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 simple 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 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. 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 depending 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 materials. 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 materials 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) of 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 control 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 historical buildings can be maintained through the use of affordable and efficient low energy solutions despite increase in the cost of energy. SIST EN 15757:2010
EN 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 professionals, which always includes a suitably qualified conservator, experienced in assessing the condition of collections and an expert in environmental control. SIST EN 15757:2010
EN 15757:2010 (E) 6
1 Scope This European Standard is a guide specifying temperature and relative humidity levels to limit 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 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 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 with 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 be 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 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 time (at least one year) and to which it has become acclimatized SIST EN 15757:2010
EN 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 where 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 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 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. 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), aff
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SLOVENSKI STANDARD
oSIST prEN 15757:2008
01-april-2008
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PDWHULDORY
Conservation of Cultural Property - Specifications for temperature and relative humidity
to limit climate-induces mechanical damage in organic hygroscopic materials
Erhaltung des kulturellen Erbes - Festlegungen für Temperatur und relative Luftfeuchte
zur Begrenzung klimabedingter mechanischer Beschädigungen an organischen
hygroskopischen Materialien
Conservation des biens culturels - Spécifications applicables à la température et à
l'humidité relative pour limiter les dommages mécaniques causés par le climat aux
matériaux organiques hygroscopiques
Ta slovenski standard je istoveten z: prEN 15757
ICS:
97.195
oSIST prEN 15757:2008 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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EUROPEAN STANDARD
DRAFT
prEN 15757
NORME EUROPÉENNE
EUROPÄISCHE NORM
January 2008
ICS
English Version
Conservation of Cultural Property - Specifications for
temperature and relative humidity to limit climate-induces
mechanical damage in organic hygroscopic materials
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 346.
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 Management Centre has the
same status as the official versions.
CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,
Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland 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: rue de Stassart, 36 B-1050 Brussels
© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 15757:2008: E
worldwide for CEN national Members.
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prEN 15757:2008 (E)
Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 General recommendations for organic hygroscopic materials .6
5 Specifications for T and RH of organic hygroscopic materials.7
5.1 Determination of Priorities.7
5.2 Constancy and homogeneity.7
5.3 Priority of historic climate .8
5.4 Further specifications .8
5.5 Measures for Climate Control.8
5.5.1 Passive and active control of T and RH .8
5.5.2 Heating for thermal comfort versus conservation needs.8
Annex A (informative) Determination of the target range for RH .9
A.1 Rationale.9
A.2 Procedure for specifying the target level of RH .9
A.3 Procedure for specifying the target range of RH .10
Bibliography .12
2
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prEN 15757:2008 (E)
Foreword
This document (prEN 15757:2008) has been prepared by Technical Committee CEN/TC 346 “Conservation of
Cultural Property”, the secretariat of which is held by UNI.
This document is currently submitted to the CEN Enquiry.
3
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prEN 15757:2008 (E)
Introduction
This European Standard gives general specifications for temperature (T) and relative humidity (RH) to
preserve cultural heritage by limiting mechanical damage induced by strain-stress cycles of organic materials
in indoor environments of museums, galleries, archives, libraries, churches and historical buildings
Materials may be divided into classes, depending on their response to relative humidity (RH):
Class 1: materials having a negligible vulnerability to RH variability, e.g. gold, glass, fossils. No special
specifications for T and RH are necessary for this Class.
Class 2: porous materials impregnated with hygroscopic salts, metals sensitive to corrosion or to
hydrolysis e.g. marine or archaeological remains, ceramics or heavily oxidised metals from
excavations, photographic materials, objects made of cellulose acetate or nitrate. These should
be preserved in a constant, dry atmosphere. Such target T and RH intervals are specified in
other European Standards.
Class 3: metastable minerals that may suffer for humidity-related phase transition, deliquescence,
efflorescence, and/or hydration, e.g., thenardite, mirabilite, hanksite, melanterite, borax, bonattite.
Each of these minerals should be preserved within precise T, RH intervals, which are the same
for all samples of the same material. Such target intervals are specified in other European
Standards.
Class 4: organic materials susceptible to fracture and deformation, or composite objects including
hygroscopic materials, with high vulnerability to RH variability, e.g. wooden artefacts, paints,
books, organs, bone, ivory, leather or textiles fixed to frames. These need individual T, RH
intervals being conditioned by the past climate history of each object; however, some general
recommendations are possible, as follows.
The determination of values and allowable variations of T and RH which are optimal for the preservation of
Class 4 objects is not simple due to the variety and complexity of the materials and the objects they comprise.
Temperature has a direct effect on preservation but also an indirect one as it controls RH of the air. Changes
in ambient RH produce changes in the equilibrium moisture content (EMC) as hygroscopic materials absorb
and release moisture to adapt to the continually changing environment. The variations in EMC produce
dimensional changes of the materials which may lead to high levels of stress and mechanical damage. For
this reason a stable climate is fundamental for preservation.
The variability in T and RH should not be considered only from the static point of view of allowable levels or
ranges, but also from the dynamic point of view, i.e. temporal features like rate of change, duration of cycles
and frequency at which cycles are repeated should be taken into account. When cycles repeat before the
material has relaxed, it accumulates internal stress, which in turn may lead to microscopic or macroscopic
forms of deterioration.
The deterioration is of cumulative nature and progresses with the number and the intensity of the individual
environmental hazards. T and RH variability accelerates material ageing although this is not always
perceptible to human eye. The vulnerability to deterioration mechanisms increases with ageing and damage is
irreversible. The same T and RH fluctuation may generate different effects in relationship to the object type
and its ageing.
When past T and RH fluctuations accumulated enough internal stress to create fractures, these fractures open
and close as expansion joints, with the result of widening the interval of acceptable T, RH fluctuations. The
material is said having “acclimatized” because now has a different response, i.e. less sensitivity, to the T, RH
fluctuations. This acclimatisation should not be considered a positive factor, because is due to internal
fracturing and actually is a form of damage.
4
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prEN 15757:2008 (E)
Given the extreme complexity of the response of historic materials to variation of T and RH, this standard lays
down general specifications to limit climate-induced mechanical damage of Class 4 objects. Therefore the
standard deals with a selected category of damage and does not cover other important deterioration
processes influenced by microclimatic factors like corrosion reactions, biodeterioration, dissolution of materials
due to deliquescence and other. The specifications for microclimatic conditions limiting deterioration
phenomena other than mechanical damage are dealt with separately by other European Standards.
1 Scope
This European Standard gives general specifications for temperature and relative humidity to limit climate-
induced mechanical damage of absorbing moisture, organic materials, especially in indoor environments of
museums, galleries, archives, libraries, churches and modern or historical buildings.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 11799 Information and documentation – Document storage requirements for archive and library
material
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
active control
use of devices that introduce or remove heat or moisture, or force ventilation
3.2
air temperature (T)
temperature read on a thermometer which is exposed to air in a position sheltered from direct solar radiation
1
or other energy sources
3.3
climate history
description of the climate conditions in the microenvironment of a cultural heritage object, over a
representative period of time, which affect its preservation
3.4
deterioration
any form of alteration, material or aesthetic, which makes worse state or lowers value of the cultural heritage
object
3.5
equilibrium Moisture Content (EMC)
moisture content at which a hygroscopic material neither loses nor gains moisture from the surrounding
atmosphere at given RH and T values
1
Definition taken from WMO (see Biliography).
5
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prEN 15757:2008 (E)
3.6
Heating, Ventilating or Air Conditioning Systems (HVAC)
active systems operated to control air temperature (heating), air temperature and humidity (air conditioning),
or ventilation in a building
3.7
historic climate
climate conditions in the microenvironment where a cultural heritage object has always been kept, or has
been kept for a long period of time and has acclimatized to it
3.8
hygroscopic material
material absorbing moisture when the environmental relative humidity rises, and loses moisture when relative
humidity drops
3.9
indoor environment
place within a building where cultural heritage objects are preserved
3.10
passive control
control of heat transfer, moisture or ventilation in a natural way, without any active control measures
3.11
Relative Humidity (RH)
2
ratio of the actual vapour pressure of the air to the saturation vapour pressure
4 General recommendations for organic hygroscopic materials
Ideally, high RH levels should be avoided. On the other hand, too low RH levels might reduce too much the
equilibrium moisture content (EMC), causing structural damage to some materials. Therefore, the optimum
RH set-point is usually specified at a mid RH range for a number of materials. However, a different approach
must be adopted for real
...
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