BS EN 16012:2012+A1:2015 BSI Standards Publication Thermal insulation for buildings — Reflective insulation products — Determination of the declared thermal performance BRITISH STANDARD BS EN 16012:2012+A1:2015 National foreword This British Standard is the UK implementation of EN 16012:2012+A1:2015 It supersedes BS EN 16012:2012 which is withdrawn The start and finish of text introduced or altered by amendment is indicated in the text by tags Tags indicating changes to CEN text carry the number of the CEN amendment For example, text altered by CEN amendment A1 is indicated by !" The UK participation in its preparation was entrusted by Technical Committee B/540, Energy performance of materials components and buildings, to Subcommittee B/540/9, Reflective insulation and in-situ testing A list of organizations represented on this committee can be obtained on request to its secretary This publication does not purport to include all the necessary provisions of a contract Users are responsible for its correct application © The British Standards Institution 2015 Published by BSI Standards Limited 2015 ISBN 978 580 85189 ICS 91.100.60 Compliance with a British Standard cannot confer immunity from legal obligations This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 February 2012 Amendments/corrigenda issued since publication Date Text affected 31 March 2015 Implementation of CEN amendment A1:2015 EUROPEAN STANDARD EN 16012:2012+A1 NORME EUROPÉENNE EUROPÄISCHE NORM February 2015 ICS 91.100.60 Supersedes EN 16012:2012 English Version Thermal insulation for buildings - Reflective insulation products Determination of the declared thermal performance Isolation thermique des bâtiments - Produits d'isolation réfléchissants - Détermination de la performance thermique déclarée Wärmedämmstoffe für Gebäude - Reflektierende Wärmedämm-Produkte - Bestimmung der Nennwerte der wärmetechnischen Eigenschaften This European Standard was approved by CEN on 23 December 2011 and includes Amendment approved by CEN on 29 November 2014 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, 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 EUROPEAN COMMITTEE FOR STANDARDIZATION COMITÉ EUROPÉEN DE NORMALISATION EUROPÄISCHES KOMITEE FÜR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels © 2015 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members Ref No EN 16012:2012+A1:2015 E BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Contents Page Foreword Introduction Scope Normative references 3.1 3.2 Terms, definitions, symbols and units Terms and definitions Symbols and units 4.1 4.2 4.3 4.4 4.5 Description of product types Product classification Product Type Product Type Product Type Product Type .10 5.1 5.2 5.3 5.4 5.5 5.6 5.7 5.8 5.9 Methods of assessment 11 General 11 Thickness measurement .11 !Test specimens" 11 Determination of thermal resistance – outline 11 Determination of core thermal resistance of Product Type 12 Determination of core thermal resistance of Product Type 13 Determination of core thermal resistance of Product Type (METHOD C) 13 Determination of the thermal performance of Product Type .18 Emissivity .19 6.1 6.2 6.3 6.4 6.5 Uncertainty 20 General 20 Thickness measurements 20 Use of surface thermocouples on thin samples in a guarded hot plate or in heat flow meter measurement .20 Use of dummy insulation specimens 20 Derivation of the core resistance of a Type Product from hot box measurements 20 7.1 7.2 7.3 Expression of results 21 Results derived from hot plate and emissivity measurements (Products Type & 2) 21 Results derived from hot box and emissivity measurements (Product Types 1, & 3) 21 Results derived from emissivity measurements only (product Type 4) 21 Report 22 Annex A (normative) 23 Annex B (normative) 24 Annex C (normative) 25 Annex D (normative) Measurement of emissivity using a Thermal Infra-Red apparatus 26 D.1 Principle of the hemispherical blackbody radiator 26 D.2 Description of suitable hemispherical blackbody radiator and specimen holder 26 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) D.3 Calibration standards 27 D.4 Calculation of the emissivity 28 D.5 Sampling and preparation of the test specimens 28 D.5.1 Sampling .28 D.5.2 Dimensions and numbers of specimens 28 D.5.3 Conditioning of specimens for ageing 28 D.6 Procedure for measurement of specimens .28 D.7 Expression of results 29 Annex E (normative) “Dummy specimen” technique for the heat flow meter apparatus 30 E.1 Principle 30 E.2 Procedure .30 E.3 Specimens of low thermal resistance .31 E.4 Calibration 31 Bibliography 32 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Foreword This document (EN 16012:2012+A1:2015) has been prepared by Technical Committee CEN/TC 89 “Thermal performance of buildings and building components”, the secretariat of which is held by SIS 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 August 2015, and conflicting national standards shall be withdrawn at the latest by August 2015 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 This document includes Amendment 1, approved by CEN on 2014-11-29 This document supersedes EN 16012:2012 The start and finish of text introduced or altered by amendment is indicated in the text by tags ! " This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association 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, 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 the United Kingdom BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Introduction Reflective (low emissivity at the appropriate wavelength) surfaces are utilized in a number of ways to enhance the thermal performance of insulating products Their role is to reduce the heat transfer by thermal radiation in some parts of the system This is achieved because low emissivity surfaces reduce the radiant heat transferred through a product that is wholly or partially transparent to infra-red radiation (e.g very low density fibrous insulation) They will also reduce the radiant heat transfer across any air gap or gaps that are present in the system In some cases, air gaps can be an intrinsic part of the structure and in other cases the insulation can be installed in such a way as to deliberately create an air gap between the reflective surfaces and the structure Unless otherwise stipulated by the manufacturer, the declared thermal performance should include an adjacent vertical air space on either side of the product, and the declared thermal performance should also include a statement of the thickness of these airspaces included as part of the declared value The declared value can, alternatively, be given as the combination of the thermal resistance of the “core” of the product together with the measured value of the emissivity of the surfaces Since all conventional thermal insulation products declare their thermal performance on the basis of the value to be expected over a reasonable working life, this is also addressed in a limited manner in this standard in the assessment of emissivity of the surface(s) of reflective insulation In the absence of any quantified and certified data on the aged performance of a facing over a normal lifetime for a building material, the ageing of the low emissivity surface is assessed by use of an accelerated ageing procedure How the thermal properties of insulation materials that utilize reflective surfaces are determined will depend on the form in which they are sold and how they are intended to be used This standard describes a number of different approaches which can be utilized and specifies which approach to use for the different types of product Where a product is already subject to a product specification that describes procedures for the measurement of the aged 90/90 fractile thermal conductivity or thermal resistance of the core insulation material, the following guidance should only be used to determine the component of its thermal performance that depends on the emissivity of its external faces However, it should be remembered that the declared value is only the first step, giving comparative performance values under specified conditions, and the design value can give more information for use by the designer in specific applications, especially under different climatic conditions BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Scope This European Standard describes a set of procedures for using existing standardized CEN or ISO test and calculation methods to determine the declared thermal performance of reflective insulation products This European Standard supports and does not replace existing CEN or ISO test methods This European Standard applies to any thermal insulation product that derives a proportion of its claimed thermal properties from the presence of one or more reflective or low emissivity surfaces together with any associated airspace(s) It does not replace the existing procedures for the determination of the thermal performance of products already covered by an existing harmonized product standard where the declared value of these products does not specifically include any claims attributable to the emissivity of the facing 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 EN 823:1994, Thermal insulating products for building applications — Determination of thickness EN 1946-1, Thermal performance of building products and components — Specific criteria for the assessment of laboratories measuring heat transfer properties — Part 1: Common crieteria EN 1946-2, Thermal performance of building products and components - Specific criteria for the assessment of laboratories measuring heat transfer properties - Part 2: Measurements by guarded hot plate method EN 1946-3, Thermal performance of building products and components - Specific criteria for the assessment of laboratories measuring heat transfer properties - Part 3: Measurements by heat flow meter method EN 1946-4, Thermal performance of building products and components - Specific criteria for the assessment of laboratories measuring heat transfer properties - Part 4: Measurements by hot box methods EN 12664, Thermal performance of building materials and products - Determination of thermal resistance by means of guarded hot plate and heat flow meter methods - Dry and moist products of medium and low thermal resistance EN 12667, Thermal performance of building materials and products - Determination of thermal resistance by means of guarded hot plate and heat flow meter methods - Products of high and medium thermal resistance EN ISO 6946, Building components and building elements — Thermal resistance and thermal transmittance — Calculation method (ISO 6946) EN ISO 7345, Thermal insulation — Physical quantities and definitions (ISO 7345) EN ISO 8990, Thermal insulation — Determination of steady-state thermal transmission properties — Calibrated and guarded hot box (ISO 8990) EN ISO 9229, Thermal Insulation — Vocabulary (ISO 9229) EN ISO 9288, Thermal insulation — Heat transfer by radiation — Physical quantities and definitions (ISO 9288) EN ISO 10456, Building materials and products — Hygrothermal properties — Tabulated design values and procedures for determining declared and design thermal values (ISO 10456) BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) ISO 8301:1991, Thermal insulation — Determination of steady-state thermal resistance and related properties — Heat flow meter apparatus ISO 8302:1991, Thermal insulation — Determination of steady-state thermal resistance and related properties — Guarded hot plate apparatus ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in measurement (GUM:1995) 3.1 Terms, definitions, symbols and units Terms and definitions For the purposes of this document, the terms and definitions given in EN ISO 7345, EN ISO 9288, EN ISO 9229 and the following apply 3.1.1 declared thermal performance value of thermal performance, declared by a manufacturer, which is derived from measured values under the specified conditions and rules given in this standard 3.1.2 indentation concave depression in the surface of the facing (foil) such that shallow air pockets are created when the surface is in contact with a smooth flat plate 3.1.3 core thermal resistance thermal resistance of the product from face to face at the tested thickness, excluding the contribution of any low emissivity outer surface or any air space(s) adjacent to the product 3.1.4 emissivity ratio of the energy radiated by a surface relative to the energy radiated by a blackbody at the same temperature 3.1.5 reflective surface low emissivity surface surface which has a low emissivity at the appropriate wavelength within the temperature range found in building elements 3.1.6 reflective insulation insulation product which has one or both external face(s) comprising a reflective surface Note to entry 3.2 It is a measure of a material's ability to radiate heat Symbols and units For the purposes of this standard, the following symbols and units apply BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Symbol Quantity Unit P perimeter M !R thermal resistance m²·K/W" U sensor signal V ε emissivity - λ thermal conductivity Φ heat flow rate Ψ linear thermal transmittance Δθ temperature difference W/(m·K) W W/(m·K) K Subscripts L low H high e edge sur surround D declared !90/90 4.1 90 % fractile with a confidence level of 90 %" Description of product types Product classification This clause describes the various generic product types to which this standard refers Product type is defined solely for the purpose of selecting the most appropriate test method (product type number does not refer to a generic species of product) Together with 4.2, 4.3 and 4.4, the flow charts in Annexes A, B and C shall be followed in assigning a given product to a product type In 4.2, 4.3 and 4.4, the product type is determined by reference to its compressibility or otherwise to achieve flat parallel surfaces This implies the removal of measurable air-gaps between the specimen and the hot and cold plates of the test apparatus whilst not unduly reducing the overall thickness of the specimen to be tested When using the weighted plate method from EN 823:1994 there shall be no residual air spaces between the weighted plate and the specimen surface The weight of plate used for the thickness measurement shall be the lowest of either plate sufficient to eliminate air gaps The thickness measured under the chosen plate shall be the thickness subsequently used for the measurement of the core thermal resistance and given in the test report 4.2 Product Type A product shall be classified as Type when it has a regular geometry with parallel faces or is compressible so that the product can be contained between the hot and cold plates of the apparatus without significantly changing its core thermal properties This is achieved when its surfaces are smooth and flat with no discernible depth of pattern or indentation BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) 6.1 Uncertainty General The measurement standards ISO 8301, ISO 8302, EN ISO 8990 and EN 1946, Parts to assist with establishing measurement uncertainties The accreditation standard ISO 17025 requires the methods in the ISO Guide to Uncertainty in Measurements (GUM) to be used The following subclauses identify the additional sources of measurement uncertainty that will be associated with the measurements specified in this standard 6.2 Thickness measurements If thermal resistance is measured, the thickness is required to define the product and set the separation of the plates in a hot plate measurement The method set out in EN 823:1994 shall be used but it might be necessary for manufacturers of these products to agree the most appropriate load to be applied to the product whilst making those measurements This measurement could introduce additional errors and shall be assessed by those carrying out the measurements 6.3 Use of surface thermocouples on thin samples in a guarded hot plate or in heat flow meter measurement Surface thermocouples shall be used when the thermal resistance of the specimen is below 0,5 m²·K/W and this procedure is always associated with additional measurement errors which need to be determined 6.4 Use of dummy insulation specimens The measurement error associated with the measurement of the dummy specimens (see Annex E) shall be combined with the measurement uncertainty associated with the test method itself using the procedures set out in ISO/IEC Guide 98-3 6.5 Derivation of the core resistance of a Type Product from hot box measurements Each step of this process will have a measurement and/or calculation uncertainty, including: i) the “normal” measurement uncertainty associated with the hot box measurement of the insulated air cavity; ii) measurement of the air cavity depths; iii) the emissivity of the test material surface 1; iv) the emissivity of the test material surface 2; v) the emissivity of the internal cavity walls (both walls assumed to be the same); vi) the uncertainty in the temperature difference between the cold face of the test element and the internal cold face of the cavity; vii) the uncertainty in the temperature difference between the warm face of the test element and the internal warm face of the cavity; viii) the calculated thermal resistance of the cold side air cavity; ix) the calculated thermal resistance of the warm side air 20 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Each of these possible sources of uncertainty shall be evaluated and combined in accordance with GUM, and the range of uncertainty included in the report 7.1 Expression of results Results derived from hot plate and emissivity measurements (Products Type & 2) !The thermal performance determined in accordance with this standard shall be established from a minimum of test results and calculated using the 90/90 fractile rules according to EN ISO 10456 as: a) the 90/90 fractile value of the thermal resistance of the core as determined in Clause 5, rounded downwards to the nearest 0,01 m²·K/W, together with; b) the 90/90 fractile value of the emissivity of the surface or surfaces (if different) as determined by D7, expressed to two decimal places, and c) optionally, depending upon the intended application, the 90/90 fractile value of the thermal resistance of the core together with the thermal resistance of one or two adjacent (vertical) airspace(s) and the specification of the air space(s), rounded downwards to the nearest 0,05 m²·K/W by: 1) Calculating the thermal resistance of the air cavities adjacent to the product using standardized calculation procedures specified in EN ISO 6946; 2) Using the emissivity of the surfaces from the procedure specified in 5.9; 3) Using the core thermal resistance determined from the procedures specified in 5.5 or 5.6; 4) Using a temperature difference across each air cavity of K, if this calculation is being carried out for the purpose of product comparison Alternatively, the air cavity thermal resistance may be calculated using a temperature difference suitable for the application The temperature difference used shall be stated with the declared thermal resistance NOTE This calculation will not be able to take account of the effects of overlapping the products (where the foil surface on the cold side is brought directly through to the warm side)." 7.2 Results derived from hot box and emissivity measurements (Product Types 1, & 3) !The thermal performance determined in accordance with this standard shall be established from a minimum of test results and calculated using the 90/90 fractile rules according to EN ISO 10456 as: a) the 90/90 fractile value of the thermal resistance of the core together with the thermal resistance of the vertical air space(s), rounded downwards to the nearest 0,05 m K/W, and the specification of the air space(s), together with, b) the 90/90 fractile value of the measured emissivity of the surfaces expressed to two decimal places, and c) the 90/90 fractile value of the thermal resistance of the core as determined in 5.7, rounded downwards to the nearest 0,01 m²·K/W." 7.3 Results derived from emissivity measurements only (product Type 4) !The thermal performance determined in accordance with this standard shall be established using a minimum of test results and calculated using the 90/90 fractile rules according to EN ISO 10456 as: 21 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) a) the 90/90 fractile value of the measured emissivity of the surface (or surfaces) expressed to two decimal places, together with; b) the calculated thermal resistance of associated (vertical) air space(s), rounded downwards to the nearest 0,05 m²·K/W, the specification of the air space(s), the temperature differences used and the calculation method used." Report The report shall include at least the following details: a) description of the product, to include at least the product name, types of facing and degree of any printing on the surface; b) product manufacturer or supplier; c) the product type determined (1, 2, or 4); d) the test method used and the conditions of test, including hot and cold face temperatures and direction of heat flow; e) the thickness used for the test and the weight of plate used for the test; f) the declared thermal performance of the product as described in Clause for the relevant product type; g) date of test; h) range of uncertainty of the test result 22 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Annex A (normative) Figure A.1 - Decision making flow chart for identification of product types 23 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Annex B (normative) Figure B.1 - Selection of test methodology for product type when using a hot plate method 24 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Annex C (normative) Figure C.1 - Selection of the measurement technique for product type 25 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Annex D (normative) Measurement of emissivity using a Thermal Infra-Red apparatus D.1 Principle of the hemispherical blackbody radiator 1) The hemispherical radiator (half sphere) in the form of a blackbody uses the thermal infra-red radiation principle (TIR-principle) The temperature of the blackbody is set and controlled at 100 °C The hemispherical shape of the radiator is necessary in order to achieve a complete and homogenous illumination of the measurement surface allowing the emissivity of rough and structured surfaces to be measured correctly Part of the energy reflected and emitted by the specimen passes through a small opening in the hemispherical radiator and is focussed onto an infra-red sensor by an infra-red lens The infra-red sensor changes the incident thermal radiation into a voltage signal in a broad band and linear manner (the voltage signal is proportional to the reflected thermal energy) At any given temperature of a blackbody, the spectral distribution of the thermal radiation is given by Planck’s law The radiator’s temperature has been chosen to be 100 °C so that the corresponding spectrum has its peak at a wavelength of circa μm and more than 97 % of the radiant energy is in the wavelength range from 2,5 μm to 40 μm Key IR lens thermopile IR sensor sample Figure D.1 — Schematic diagram of typical thermal infra-red apparatus D.2 Description of suitable hemispherical blackbody radiator and specimen holder In order to reduce errors related to the hemispherical blackbody radiator (henceforth referred to as “apparatus”) to a minimum, the half sphere should have a diameter of not less than 70 mm The distance of the specimen surface to the apparatus shall be approximately mm The axis of the infra-red sensor and 1) The TIR (Thermal Infra-Red) apparatus described in this standard has previously been developed and specified in EN 15976 (see Bibliography) 26 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) infra-red lens assembly shall point at the centre of the specimen and shall be between 70° and 80° to the specimen surface An adequate electronic method to evaluate the measuring signals should be applied In order to avoid heating of the specimen, the measuring time should be limited to a maximum of seconds The specimen holder should have a solid flat front surface with a minimum of 140 by 140 mm The fixing of the specimen onto the specimen holder should be adapted to the type of material being tested The specimen shall be flat and wrinkle-free over the whole surface Thin materials may be wrapped around the left and the right edges of the specimen holder and then fixed on both sides by magnetic strips For metal foils, heat-sink coupling is very important (use heat conductance paste to couple to the heat sink) and a massive aluminium plate as a heat sink should be used For thick and stiff materials, fixing should be adapted on a case-by-case basis (clamps, hooks, etc.) The specimen shall be maintained parallel to the apparatus during measurement The distance of mm between specimen and apparatus shall be pre-defined by spacers, which should also prevent any rocking of the specimen Key specimen test equipment IR beam Figure D.2 — Arrangement of thermal infra-red apparatus and specimen D.3 Calibration standards The apparatus requires calibration against accurately defined low and high emissivity standards Typical calibration standards for a low emitting surface should have 0,01 < εL < 0,02 For a high emitting surface, the calibration standard should have εH > 0,94 The recommended reference standards should be based on: — low emissive standard: polished aluminium surface; — high emissive standard: black light trap surface Calibration standards shall be certified by the manufacturer of the apparatus or by an independent institute, accompanied by a certificate showing the measured emissivity The calibration standards shall be recertified (or replaced by new certified standards) at least every two years 27 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) D.4 Calculation of the emissivity The emissivity is determined from comparing the measured result for the specimen with the two calibration standards With the sensor signals (U, UH and UL) and the known emissivity of calibration standards (εL and εH), the emissivity, ε, of the specimen shall be calculated by: є = єH - (єH - єL) × (UH - U) / (UH - UL) (D.1) NOTE The measurement range of the apparatus is limited to values between those of the two calibration standards used, hence within the emissivity range of 0,02–0,94 However, there are practical limits to the measurement of very low values of emissivity, irrespective of the method used Errors increase significantly below emissivity 0,05 D.5 Sampling and preparation of the test specimens D.5.1 Sampling A sample of an undamaged reflective insulation product shall be selected at random from a batch of production material or from product placed on the market D.5.2 Dimensions and numbers of specimens !A minimum of three specimens should be taken from the sample to be representative of the length and width of the product to include a representative area of any printing or perforation where relevant If the faces of the product differ then a minimum of three specimens shall be taken from each face The specimen size should be adapted to the size of the specimen holder and to the fixing system of the specimen holder (see D.6), but shall be at least 250 mm by 250 mm." D.5.3 Conditioning of specimens for ageing The specimens shall be exposed in a climatic chamber to 90 % relative humidity and 70 °C temperature for a period of 28 days The edges of the specimens shall be adequately protected by securing self-adhesive aluminium foil tape around each edge of the specimen from the upper surface to the lower surface, to prevent ingress of moisture through the cut edge After the conditioning process, the specimens shall then be allowed to stabilize for a minimum of two hours at a temperature of (23 ± 2) °C and relative humidity of (50 ± 20) % D.6 Procedure for measurement of specimens The apparatus shall be switched on at least hours before calibration and before commencing measurements The apparatus shall be installed in a fixed position and shall not be moved during measurement Special precautions should be taken to ensure that the calibration standards, the specimens and the apparatus are brought to equilibrium in the same standard climatic conditions Air currents and draughts in the measuring area shall be avoided The specimen shall be brought up to the apparatus in a vertical orientation, pressed against the spacers around the measuring window of the apparatus and the apparatus shall be activated to begin measurement The emissivity shall be measured in five positions on each specimen In order to avoid changes in the specimen temperature during the measurement, the time that the specimen is left in the measuring position shall be reduced to a minimum Between specimen positioning and start of measurement, no more than second shall pass If this speed of measurement is not achieved, or if the measurement is otherwise interrupted, or if the measurement on a specimen is to be repeated, the specimen should be withdrawn from the apparatus for the time it needs to cool down to laboratory temperature Rapid movement of the specimen over the apparatus while measuring is possible, but coupling of the specimen to a massive aluminium block by heat conductance paste gives the most consistent results The higher the emissivity and/or the lower the 28 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) specific heat capacity of the material, the longer the specimen will need to cool down to laboratory temperature In order to reduce measurement variability to a minimum (laboratory, specimen and apparatus related), the apparatus shall be recalibrated using the two calibration standards at least once per hour of use NOTE In order to measure values with highest possible repeatability, the following should be observed: a) all corresponding tests should be carried out by the same person; b) re-calibrate the apparatus for each specimen; c) use heat conductance paste and a massive aluminium heat-sink; d) sink; measure only reflective sheets, not the additional wadding or other materials in between the foil and the heat- e) ensure the measuring time is less than 1,5 seconds; f) allow enough time for apparatus to heat up before starting the test (approximately hours) D.7 Expression of results !The emissivity of the specimen shall be expressed to decimal places All single measurements resulting in an emissivity < 0,02 or > 0,94 (measurement range of the apparatus) should be set to 0,02 or 0,94 respectively The emissivity mean value, all the single values per specimen and the standard deviation of the results from the tested product shall be included on the test report The emissivity mean-value shall be rounded to two decimal places The mean value (one test result) from any one sample shall be derived from a minimum of specimens taken from the sample with five measurements being taken on each specimen The declared value for a product shall be based upon a minimum of test results (wherever possible from at least different production batches) calculated using the 90/90 fractile rules from EN ISO 10456 The manufacturer may use a higher number of test results (samples) in the calculation A mean value below 0,05 is declared as 0,05." 29 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Annex E (normative) “Dummy specimen” technique for the heat flow meter apparatus E.1 Principle Heat flow meter apparatus needs to be calibrated with reference materials having similar thermal performance to the materials being tested As most heat flow meter apparatus will not have been calibrated with thin reference materials (< 20 mm thick), a method is given in this annex to ensure that thermal resistance measurements made on such thin materials, in a heat flow meter apparatus, conform to ISO 8301 This method is referred to as the “dummy specimens” method E.2 Procedure In this method, a pair of “dummy specimens” each not less than 10 mm thick shall be used to make a composite specimen of a thickness that is covered by the reference samples used to calibrate the heat flow meter apparatus Two measurements shall be made using the specimen arrangements illustrated in Figures E.1 and E.2: 1) using only the two dummy specimens, to determine their combined thermal resistance; 2) with the specimen under test sandwiched between the two dummy specimens 3) The thickness of the test specimen shall be maintained by the use of suitable low conductivity spacers set to the measured thickness of the test specimen and placed between the dummy specimens outside the metering area The thermal resistance of the material under test shall then be derived from the results of these two measurements as the difference in thermal resistance between the second test and the first test Key cold plate dummy specimen dummy specimen hot Plate Heat Flux Transducer Figure E.1 — Schematic diagram of dummy specimen arrangement 30 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Key cold plate dummy specimen dummy specimen hot Plate Heat Flux Transducer thin specimen being tested Figure E.2 — Schematic diagram of dummy specimen arrangement with specimen under test E.3 Specimens of low thermal resistance In the case where the test specimen (excluding the dummy specimens) is expected to have a thermal resistance of less than 0,5 m K/W, surface thermocouples shall also still be used E.4 Calibration To achieve a 10 K temperature difference across the test specimen requires a temperature difference of approximately 50 K across the whole stack This requires a separate calibration file to be established with this temperature difference across the reference specimen 31 BS EN 16012:2012+A1:2015 EN 16012:2012+A1:2015 (E) Bibliography [1] 32 EN 15976:2011, Flexible sheets for waterproofing - Determination of emissivity This page deliberately left blank NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW British Standards Institution (BSI) BSI is the national body responsible for preparing British Standards and other standards-related publications, information and services BSI is incorporated by Royal Charter British Standards and other standardization products are published by BSI Standards Limited About us Revisions We bring together business, industry, government, consumers, innovators and others to shape their combined experience and expertise into standards -based solutions Our British Standards and other publications are updated by amendment or revision The knowledge embodied in our standards has been carefully assembled in a dependable format and refined through our open consultation process Organizations of all sizes and across all sectors choose standards to help them achieve their goals Information on standards We can provide you with the knowledge that your organization needs to succeed Find out more about British Standards by visiting our website at bsigroup.com/standards or contacting our Customer Services team or Knowledge Centre Buying standards You can buy and download PDF versions of BSI publications, including British and adopted European and international standards, through our website at bsigroup.com/shop, where hard copies can also be purchased If you need international and foreign standards from other Standards Development Organizations, hard copies can be ordered from our Customer Services team Subscriptions Our range of subscription services are designed to make using standards easier for you For further information on our subscription products go to bsigroup.com/subscriptions With British Standards Online (BSOL) you’ll have instant access to over 55,000 British and adopted European and international standards from your desktop It’s available 24/7 and is refreshed daily so you’ll always be up to date You can keep in touch with standards developments and receive substantial discounts on the purchase price of standards, both in single copy and subscription format, by becoming a BSI Subscribing Member PLUS is an updating service exclusive to BSI Subscribing Members You will automatically receive the latest hard copy of your standards when they’re revised or replaced To find out more about becoming a BSI Subscribing Member and the benefits of membership, please visit bsigroup.com/shop With a Multi-User Network Licence (MUNL) you are able to host standards publications on your intranet Licences can cover as few or as many users as you wish With updates supplied as soon as they’re available, you can be sure your documentation is current For further information, email bsmusales@bsigroup.com BSI Group Headquarters 389 Chiswick High Road London W4 4AL UK We continually improve the quality of our products and services to benefit your business If you find an inaccuracy or ambiguity within a British Standard or other BSI publication please inform the Knowledge Centre Copyright All the data, software and documentation set out in all British Standards and other BSI publications are the property of and copyrighted by BSI, or some person or entity that owns copyright in the information used (such as the international standardization bodies) and has formally licensed such information to BSI for commercial publication and use Except as permitted under the Copyright, Designs and Patents Act 1988 no extract may be reproduced, stored in a retrieval system or transmitted in any form or by any means – electronic, photocopying, recording or otherwise – without prior written permission from BSI Details and advice can be obtained from the Copyright & Licensing Department Useful Contacts: Customer Services Tel: +44 845 086 9001 Email (orders): orders@bsigroup.com Email (enquiries): cservices@bsigroup.com Subscriptions Tel: +44 845 086 9001 Email: subscriptions@bsigroup.com Knowledge Centre Tel: +44 20 8996 7004 Email: knowledgecentre@bsigroup.com Copyright & Licensing Tel: +44 20 8996 7070 Email: copyright@bsigroup.com