19.10.2004
Status on NORDTEST project: Moisture Buffering of Building Materials
Carsten Rode
Department of Civil Engineering, Technical University of Denmark
The following is mainly an extract of the status report sent to the NORDTEST organization by the
end of the project’s first phase in the middle of September 2004. The project is currently in a
“hibernation phase” since we are waiting for NORDTEST’s approval to continue with Phase 2 of
the project (planned for Nov. 2004 – June 2005).
The project took an offset in fruitful presentations and discussions carried out at a Workshop in
August 2003. From this workshop we knew that the project idea was judicious.
Two working meetings have been arranged in the period since the official project start:
- At EMPA Zürich, May 14. This was arranged in continuation of a meeting earlier the same
week in IEA ECBCS Annex 41. Thus the NORDTEST meeting had participation from a substantial
group of external partners, including three members of our international reference group. The
minutes of the meeting are attached to this note as Appendix 1. Prior to the meeting was prepared
an ”Initial Review Report” with contributions from the project partners. The review report declares
the theoretical definitions used in the project, and they were discussed at the meeting.
- At Byggforsk, Trondheim, August 16 (minutes of the meeting attached as Appendix 2). The
main issues were discussion of the test protocol draft (Appendix 3) and presentations of results
and problems of a first comparative test with a reference material. Also first presentation of a
computer program for conversion of relevant moisture buffer properties.
It has been agreed to submit a paper for the Nordic Building Physics Symposium in June 2005
about the project – an abstract is attached as Appendix 4.
In June 2004, the project members were advised by Chris Sanders of Glasgow Caledonian
University about a Japanese standard (JIS A 1470-1) on a related topic, which is now proposed as
an ISO standard. The project group has discussed the Japanese proposal to find if there is overlap
with our ongoing work. There are indeed some similarities in the methods – but also some
differences. The Japanese Standard is only for building materials, where our work is for other
materials used in indoor furnishing as well.
We propose to NORDTEST that our work should be completed as planned. Particularly since
some of what is now missing in our project is the round robin testing where data are obtained, and
where we will have the most interaction with industry partners who have supported the project, and
should benefit from it.
Phase II comprises primarily to carry out the round robin testing of typical materials from industry
partners, and to write the NORDTEST method (it will consist mainly of the theoretical definitions
and the test protocol). Some dissemination activities will take place as well, including planned
contribution to a public meeting arranged with Fuktcentrum, Lund, Nov. 22, 2004. The next work
phase will be mainly by correspondence and work with local industry contacts, so no further
plenary meetings are planned until one in June 2005 – probably in connection with the Building
Physics Symposium in Reykjavik.
Appendix 1
CAR, June 10, 2004
Minutes of meeting in NORDTEST project on Moisture buffer Capacity, ETH Zürich,
May 14, 2004, 13:15 - 17:00
Participants
(See IEA Annex 41’s member list: http://www.kuleuven.ac.be/bwf/projects/annex41/members.htm for addresses):
NORDTEST partners:
Carsten Rode, DTU (chairman)
Berit Time, NBI
Tuomo Ojanen, VTT
Kaisa Svennberg, LTH
Lone Hedegaard, DTU
Members of international reference group:
Andreas Holm, FhG - IBP
Nuno Ramos, UP
Nathan Mendes, PUCPR
Observers:
Karim Ghazi Wahili, EMPA
Chris Sanders, GCU
Mike Davies, UCL
Theodore Chen, UCL
Olga Koronthalyova, SAS
Peter Matiasovsky, SAS
Heiko Fechner, TUD
Juha Vinha, TUT
Arnold Janssens, UGENT
Carey Simonson, U of S
Jos van Schijndel, TUE
Vasco Peixoto Freitas, FEUP-UP
Targo Kalames, TTU (Tallin Techn. Univ.)
Paul Fazio, Concordia University
Kumar Kumaran, NRC Canada
Achilles Karagiozis, ORNL
Hua Ge, Concordia
Evaristo Rodriguez, UDC
Agenda:
1. Opening of the meeting
2. Review of project plan and schedule
3. Contractual matters
4. Definition of the term: Moisture Buffer Capacity, incl. its relations to standard hygrothermal properties.
5. Test procedures and round robin tests
6. Involvement of industry
7. Work plan
8. Next meeting
9. Closure
1. Opening of the meeting
The meeting was held as an extension to the IEA ECBCS Annex 41 working meeting held at ETH May 1214, 2004.
Carsten Rode welcomed the many guests for the meeting, some of whom had also volunteered to act as
members of an international reference group for the project since it was fostered at the NORDTEST
Workshop at the Technical University of Denmark, August 21-22, 2003. The summary report from the
Workshop can be found under: http://www.byg.dtu.dk/publications/rapporter/byg-r067.pdf
2. Review of project plan and schedule
Carsten Rode gave an overview of the project (and the NORDTEST organisation and projects in general).
The project runs in two phases. Phase I comprises the definition of the term Moisture Buffer Capacity and
writing of a proposal for relevant test methods, including relations to standard hygrothermal properties.
Phase I must be reported to NORDTEST by September 15, 2004. Phase II is the implementation of the
ideas from Phase I: A round robin will be carried out, and the NORDTEST Method will be written and then
sent for remiss. Some dissemination activities should be carried out by the end of the project, and comments
are invited from the public by the end of Phase I. The whole project should be completed by Summer 2005.
3. Contractual matters
The core partners should sign and send their collaboration agreement to DTU. Each partner is responsible
for agreements with their national industrial partners. However, we must collect documentation of their
financial or in-kind support. We have more or less the anticipated industry participation, but more
contributions shall still be welcomed.
4. Definition of the term: Moisture Buffer Capacity, incl. its relations to standard hygrothermal
properties.
The four core partners had prepared some short review papers before the Zürich meeting, summing up, from
the perspective of each partner, the important results of the workshop in August and input from the literature.
The papers were collected in a short report "Initial Review of Definitions and Methods" and distributed at the
meeting.
The subsequent discussion touched on many relevant properties and relevant factors:
• Moisture penetration depth, Moisture effusivity, Available water.
• The concept of Moisture Buffer Performance was proposed when referring to conditions in whole rooms,
and Moisture Buffer Capacity should relate only to individual materials, and possibly to material
combinations. However, whole rooms are out of the primary scope of this project, but possibly one could
define a concept, such as Active volume, comprising all materials in a room.
• There is a problem with how materials are configured geometrically in a room, and their surface film
coefficients, surface coatings and other multi-layered structures.
• Some possibilities for classification of moisture buffer capacity were proposed by several of the
participants, but the topic was not concluded upon.
• Also, one could define a reference material to which other materials could compare by a factor – like µvalue for vapour permeability.
• How can furniture be treated - possibly as modified air?
• It would be relevant to link the buffer performance property to standard hygrothermal properties - one
could perhaps do with just the moisture diffusivity.
• A calculation tool to make the conversions would be useful, and will be considered by LTH.
• One should be aware that the conditions have a non-linear nature. This is relevant for the choice of RH
levels at which the tests are to be carried out. Preferably, this should match some realistic saturated salt
solutions (e.g. 23, 50 and 75 % RH are possible).
To make the discussions converge it was proposed to work towards a dual definition:
• A theoretical definition - the moisture effusivity, bm, and
• An industrial definition - ∆m8h.
The first is a dynamic property of a material, which can theoretically be deduced from vapour transport and
sorption properties determined under steady state conditions. However, one should bear in mind that for
some materials, properties determined under steady state may not be valid in dynamic situations. bm may not
be an intuitive quantity for lay people.
The second property simply expresses the quantity of moisture exchange in a given dynamic exposure, e.g.
for 8h/16h step changes or, possibly, daily sinusoidal variation.
5. Test procedures and round robin tests
Overview of which facilities are available to the project
The partners explained which test facilities are available to them:
• LTH: Jar method.
• NBI: Bigger jars (from Berit’s Dr.Ing.)
• VTT: Box for step changes of RH
• DTU: Refrigerators and Megacup.
In addition, it was indicated that FEUP and IBP had equipment with which they would also participate in the
round robin on a voluntary basis.
It should be possible for all partners to participate in the project's material testing with the different
equipments they have already. Typically: some climatic chambers of various kinds. A question is how the
climatic exposure can be controlled, e.g. for step changes. This way, it will eventually also be more feasible
for industry to do this kind of testing.
Discussion of test protocols. A test protocol must be developed, and we will start this work now. Berit
Time prepares a first draft. The effectiveness of the test protocol will be tested already in phase I of the
project by the different partners' use of a preliminary round robin material: Tuomo Ojanen will provide some
Finnish spruce plywood. The preliminary round robin would possibly be followed up with tests on material
from Maxit (Optiroc).
6. Involvement of industry
Contracts/agreements with companies
Which materials and measurements?
Mentioned on the “financing slide of Carsten’s PowerPoint presentation (attached in pdf-format). See also
agenda item 3.
7. Work plan
Phase I runs until September 2004 (deadline for the interim report is Sept. 15). Deliverables must be
planned tightly.
See agenda item 2, and Carsten’s PowerPoint presentation.
8. Next meeting
NBI, Trondheim, August 16, 2004.
9. Closure
Carsten Rode thanked the EMPA and ETH for their kind hospitality in making the facilities available for the
meeting, and all the participants for their sincere interest in the topic and the project.
Appendix 2
CAR, September 8, 2004
Minutes of meeting in NORDTEST project on Moisture buffer Capacity, Byggforsk, Trondheim,
August 15-16, 2004
Carsten Rode, BYG·DTU,
Draft - September 1, 2004
Participants:
Berit Time, NBI
Arild Gustavsen, NTNU (participated until noon August 16)
Tuomo Ojanen, VTT
Kaisa Svennberg, LTH
Jesper Arfvidsson, LTH
Carsten Rode, DTU (chairman)
Agenda:
Sunday, August 15, Common dinner in Trondheim
Discussion of status:
• The initial review report (pre-Zürich)
• Zürich meeting
• What needs to be done in the rest of Phase 1 of the project?
Monday, August 16
Administrative matters (contracts and industry contacts, status)
Moisture Buffer Capacity definition.
• What's in it now - and what isn't
• Publication for the definition of MBC
• Relation to standard moisture transport properties
Test methods
• Overview of applicable methods (by the partners)
• The Japanese/proposed ISO standard
• First comparative tests (all partners report their results)
• The test protocol document (this should be the focus of this meeting!)
• Comments from FEUP
• Ideas for follow-up tests (also depends on phase II and the industry involvement)
Time plan until September 15
• Deliverables
• Status report for NORDTEST
• Permission to continue with Phase II
• Distribution of duties
Public meeting
Phase II, overview:
• Round robin begins
• Industry involvement
• Writing of NORDTEST method
Sunday, August 15,
Discussion of status:
The division of the project into two phases, and the content of the two phases, was rehearsed. Phase I with
state-of the-art assembly, proposal for a definition of Moisture Buffer Capacity, and proposal for a test
protocol should be reported to NORDTEST together with the request for permission to continue with the
project’s Phase II. Phase II deals with the actual writing of the NORDTEST method, and round robin testing
of reference materials. The intermediate report and renewed application should be sent to NORDTEST by
September 15.
• The initial review report (pre-Zürich) and issues from Zürich meeting
The initial review report will be added as an attachment to the reporting we send to NORDTEST by the end
of Phase I.
• What needs to be done in the rest of Phase 1 of the project?
We need to be very accurate to fulfil the requirements of deliverables by September 15, such that we can
foresee a smooth transition into Phase II of the project. Responsibilities will be distributed tomorrow.
Monday, August 16
Administrative matters (contracts and industry contacts, status)
Each partner is responsible for the industry contacts in their own country. Documentation of the contribution
by the industry contacts (whether monetary or in-kind) needs to be collected such that we can prove this
contribution to NORDTEST. This documentation should be kept in the files of the individual partners and a
copy sent to the project leader (DTU).
The partners can send an invoice to DTU for their share of Phase I of the project in connection with the
intermediate reporting to NORDTEST.
Moisture Buffer Capacity definition
• What's in it now - and what isn't
We will base the definition on two quantities which supplement each other:
bm
- Moisture Effusivity This is the theoretical value and can only be determined for a pure
material
∆m8h
- Moisture Buffer Value. This is a practical value that can be assessed from an experiment
(moisture uptake after 8 hour exposure to a new climate) - also possible for composite materials.
- A theoretical relation exists between bm and ∆m8h.
- The quantities are characteristic of individual materials/surfaces – not assemblies like in complete rooms.
The definitions apply not only to building materials, but possibly also to furniture and textiles etc.
- We cannot be too precise about the influence of the surface film coefficient, although for some materials it
may be an important factor. We will not specify certain test conditions in terms of air circulation, but the effect
should be demonstrated. As far as possible materials should be tested under conditions similar to their
intended use, and the test circumstances should be reported. (Something like that, was that what we agreed
upon…?)
- The number is a figure of merit for design. We should demonstrate how it can be used – e.g. come with an
example.
- A graphic illustration in the form of a scheme will describe the relationship between:
- Level 1: The MBC concept
- Level 2: Moisture Effusivity and Moisture Buffer Value, respectively
- Level 3: Standard hygrothermal properties.
- In addition, we could/should introduce yet another number, a, which can be seen as parallel to the capillary
water uptake coefficient, i.e. the square time development of moisture uptake.
•
Publication for the definition of MBC
The definition will of course be given as part of the NORDTEST method, when we come to that in Phase II.
But already now, we will prepare a paper for the next Nordic Building Physics Symposium (Reykjavik, June
2005), where the definitions will also be given.
• Relation to standard moisture transport properties
LTH will prepare a program to make the translation between Moisture Buffer Value and standard
hygrothermal properties. A first version moistbuf developed by L.-E. Harderup, was demonstrated. The
program can read measured results. It can check the surface film coefficient. The program can be distributed
to the participants (current version has a decimal point/comma problem).
Test methods
•
The Japanese/proposed ISO standard
A Japanese standard (JIS A 1470-1) was proposed to be raised as an ISO standard, and it is quite similar in
topic to our work. It was sent to Carsten from Chris Sanders after our Zürich meeting, and afterwards, it also
turned out that Arne Elmroth/Margaretha Andersson have had it since Feb. 04 – but they were not aware of
our work. The JIS is only for building materials, where our work is for other materials as well. There are some
similarities in the methods – but also some differences. Carsten will ask Chris about the current status of the
standard in the ISO system. Also, we will inform NORDTEST about the JIS/ISO when we report to them in
mid-September.
•
Overview of applicable methods (by the partners), and
•
First comparative tests (all partners report their results)
VTT, Byggforsk and DTU have the following equipment available by the partners for the initial experimental
testing of Moisture Buffer Value:
-
Byggforsk uses equipment from Berit’s Dr.Ing. work. Specimens are moved between two vessels
with different relative humidities, which are maintained by saturated salt solutions. Weighing is done
automatically with 10 minutes intervals using a scale with 1 mg resolution. The equipment currently
2
has no fan, so airflow is uncontrollable. ∆m8h = 24.4 g/m was found in 6.5 hours
-
VTT has equipment where the sample is moved from chamber to chamber. There is a fan, but it is
2
not efficient. ∆m8h = 18.5 g/m was found in 8 h’s. Weighing is manual. Some nice weight vs. square2 ½
root-time curves were obtained, and a was calculated to be 0.110 g/m s .
-
DTU has refrigerator chambers where the air humidity is controlled by mixing of moist and dry air.
The RH control is very accurate but changes take place over some 30 minutes when going from 33
to 75% RH. There is a fan, which in the preliminary testing has been switched off. Weighing is done
2
automatically, e.g. with 5-min. intervals, on a scale with 1 mg resolution. ∆m8h = 26.5 g/m was found
in 8 h’s.
-
LTH was planning to use JAR method and possibly the vial cup, but so far there had been problems,
so no results yet.
All first tests have been done with 33 / 75% RH setpoints in 16 / 8 hour daily shifts. Each of us shall now
continue these first tests so we have three duplicates of the spruce plywood tests with our equipment. All
results should be sent to Kaisa who will collect them (hopefully before Sept. 15…?). Tuomo has sorption
curve and vapour perm. data for the spruce plywood, and he will send this information to all.
It was agreed that for future tests, the results should be reported also pr. % RH change in the exposure.
•
The test protocol document
Comments and discussion were based on the last distributed version of the document (29.06.2004).
Comments relate to the section numbers:
Title:
capacity -> value
building materials -> material exposed to indoor air
1. Specify the number of measurements to be done pr. day.
2. Accuracy of the scale: The end result must not be affected by more than 1%
3. Thickness should be at least the moisture penetration depth (which definition?). If not, materials
should be used as they would be installed in practice.
More specific information needed about sealing.
Some info needed about horiz./vertical positioning of the specimen.
How many open/sealed faces?
Initial equilibrium should be 50 % RH (or 54 % RH), or mean RH of exposure during test.
4. 33 – 75 % RH should be the main choice, but also alternative choices:
33 – 54 %
54 – 75 %
75 – 93 %
The choices should reflect probable applications of the material…
There should be specified a requirement on the RH accuracy.
The tests should last for at least 3 days, and the amplitude of the weight variations must not differ by
more than 5% of the specimen weight when comparing the last two days.
There should be a minimum of 5 weighings of the specimen in 8 hours on the last day.
4.2 Delete “if possible”. Exposed area should be determined after edge sealing has been carried out.
4.3 Movement to scale must not influence the result by more than 1% of the amplitude.
5. ∆m should be reported pr. m , and pr. ∆RH.
2
Classification: Probably a good idea, but this is future work for when we have the experience.
Also report the initial ∆m/sqrt(t) value (or a-value) – this is particular important for thin/lightweight
materials.
•
Comments from FEUP
On 23.07.2004 we received the following comments from FEUP, Porto – here with the answers agreed
during the meeting:
1.
Will the definition of the Moisture Buffer Capacity of building materials, based only on the proposed test procedure,
benefit materials that present higher vapour permeability, in detriment of materials that have a higher moisture capacity but
less vapour permeability?
Perhaps. Can be analyzed.
2.
The proposed test looks essentially at the daily cycle, but a season cycle can also be important. Shouldn’t there be a
reference to the season cycle performance of the materials?
We concentrate on daily cycles. Other periods can then be calculated analytically.
3.
We think that the sorption flux density coefficient could also be retrieved from the initial phase of the test, and so maybe
that could also be a result from the test?
Yes, this will be specified as a possible additional result.
4.
We present on table 1, a possibility of combining additional information to the test results.
We are changing the limits, but not exactly to those proposed by FEUP.
•
Ideas for follow-up tests (also depends on phase II and the industry involvement)
None, but see the note above about also reporting the a-value (∆m – square time relation).
Time plan until September 15
• Deliverables and distribution of duties
Responsibilities for the deliverables were distributed:
Initial Review Report: Carsten
Test Protocol: Berit
First test results (spruce):
Carsten with input from all collected by Kaisa.
Computer program with document that describes relationships to well-known properties: Kaisa
and Jesper
Abstract for Nordic Building Physics Symposium: Carsten
• Status report for NORDTEST and Permission to continue with Phase II
Carsten will collect the reporting based on the above-mentioned deliverables and send it to NORDTEST
by/before September 15.
Public meeting
Public meeting: November 22, 2004. The NORDTEST project and theme will be presented as part of
FuktCentrum´s public information day in Lund. This year with the theme: “Fuktskyddsdokumentation”.
Responsible. Jesper and Carsten
Phase II, overview:
• Round robin begins
Strictly, we don’t have NORDTEST’s permission to continue with Phase II yet. But let us be optimistic and
prepare so much that we arrange for the materials to be tested in the next phase to be delivered and preconditioned. Some of them may take some time to equilibrate.
•
Industry involvement
•
Writing of NORDTEST method
Third common meeting
This meeting is meant to be held by the end of Phase II. We will try to arrange this to be held on June 12,
2005 in conjunction with the Nordic Building Physics Symposium in Reykjavik.
Appendix 3
September 9, 2004
DRAFT –
MEASURING OF MOISTURE BUFFER VALUE FOR
MATERIALS EXPOSED TO INDOOR AIR
1.
Scope
The scope of this NORDTEST method is to evaluate the moisture buffer value for materials
exposed to indoor air, i.e. building materials, furniture, curtains etc. The test is intended to simulate
daily variations.
2.
Field of application
The method is applicable to materials intended for use indoor.
3.
References
??
4.
Definitions
Moisture buffer value in this connection refers to the moisture uptake/release when the material is
exposed to a square wave in relative humidity between 33 % and 75 % during 8 hours/16 hours.
5.
Method of test
5.1
Principle
A test specimen, partly sealed, is exposed to a square wave in relative humidity conditions. The
temperature is held constant. Because of the change in RH, the specimen will gain or loose weight.
The weight change of the specimen is monitored continuously or by using repetitive weighings. The
change in weight can be considered as an expression of the moisture buffer value of the test
specimen.
5.2
Experimental equipment
A climate chamber/climate box where temperature and RH can be kept constant and where the
proposed RH-step can be performed shall be used. Suitable sensors and a logging system to
continuously record the temperature and the relative humidity within the test chamber shall be used.
The sensors shall be calibrated at regular intervals.
An analytical balance, capable of weighing the test specimens with the repeatability of 1 % shall be
used. That means for example for a test sample with a change in mass of 1 g per 8 hour a balance
with a resolution of 0,01 g or better should be used, correspondingly for a test sample with a change
in mass of 10 g per 8 hours, a resolution of 0,1 g or better can be used.
The air in the test chamber should circulate and the air velocity should be more than 0,1 m/s.
However the air circulation must not disturb the balance.
5.3
Test specimens
5.3.1
General
The test specimens shall be representative of the product.
5.3.2
Exposed area
The shape and size of the test specimen is not fixed, but rectangular shapes are recommended. The
minimum side length or diameter of the exposed area of the specimen is recommended to be 100
mm and minimum exposed face area is 0,01 m2. Representative circular test specimens
(homogeneous surfaces) or smaller test specimens can be allowed.
3.3
Sealing of specimen
Rectangular test specimens shall normally be sealed on 4 (?) or 5 out of 6 sides. Other test
specimens should have as many sides exposed as in the intended use.
Sealing materials could be… (wait for the results from Lund towards the end of the year)
3.4
Thickness of test specimens
The thickness of the specimen should be at least the moisture penetration depth (which definition ?).
Whenever possible, the thickness of the specimen shall be that of the product in use. If the criteria
above are fulfilled the following thicknesses can be used:
For products/specimens with “non-defined” thickness; Thickness minimum 10 mm
For composite products with “non-defined” thickness; An assembly thickness of 10 mm
Recommended thickness of the test sample depends mainly on the water vapour permeability of the
material measured using the wet cup method (50/97 % RH). The level of the coefficient can be
taken from literature or it can be measured. In case of uneven material thickness (panel carvings
etc.), the value corresponds to the minimum thickness of significant area of the specimen surface.
(3.5
Surface coating of test specimens
In some cases the test products may have surface coatings or they may consist of different material
layers. The determined result is then not a pure material property. It is recommended to measure the
product with and without the coating layer if the disconnecting of the surface layer is possible
without causing significant changes to the surface properties of the actual base material. )
3.6
Number of test specimens
A minimum of 3 test specimens shall be tested
3.7
Conditioning of test specimens
Before testing, the test specimens shall be stored an initially be in equilibrium with 50 % RH or
mean RH of exposure during test. The criteria for equilibrium is a period long enough for the
weight of the sample to stabilise so that two successive daily determinations (24 hours between) of
the weight agree to within 0,1 % of the mass of the test specimen.
4
Procedure
4.1
Test conditions
The test environment is given in Table 3. Set A should be the main choice, but if the application of
the material fits better to another set (B, C or D) these could also be alternatives.
Table 3
Test conditions
Set
A
B
C
D
Temperature (° C)
23
23
23
23
Low RH (%)
33
33
54
75
High RH (%)
75
54
75
93
Table4:
Salt solutions and performance characteristics (Greenspan 1977, Nyqvist 1983
Bertelsen 1984)
RH at 20°C [%]
33…..
54,6±0.2
75,5±0.1
94,6±0,7
Salt
MgCl2
Mg(NO3)2
NaCl
KNO3
Name
Magnesium Choride
Magnesium Nitrate
Natrium Chloride
Kalium Nitrate
dRH/dT [%/°C]
0.3
-0.03 (?)
-0.18
A minimum of 3 cycles (3 times 24 hours) should be performed or until the change in ∆m is less
than 5 % between two successive cycles (days) ( Could we have a principle figure here ?). The high
RH level should last for 8 hours. The low RH level should last for 16 hours.
If not the weight gain/loss are monitored continuously, at least 1 weighing have to be done at each
level. There should be a minimum of 5 weighings of the specimen in 8 hours on the last day.
4.2
Preparation of specimen and test facility
Prepare test specimens. Measure the thickness and the exposed area after the sealing have been
done.
4.3
Test procedure
Place the test specimen in the test chamber.
Record/Perform the weighing. Weighings shall be carried out in an environment with a temperature
within +/- 2 °C of the test condition, wherever possible within the test chamber.
Movement to scale must not influence the result by more than 1 % of the amplitude.
Plot a curve of the mass against time.
5.
Calculation and expression of results
The result shall be calculated as mass-change (m8 hours-m0) per m2 and per ∆ RH
A result shall be calculated for each cycle. The Moisture Buffer Value is the average of minimum 3
cycles (??the average of the cycles that are within the ± 5 %..)
The initial ∆m/sqrt(t) value (or a-value (should be defined earlier)) should be plotted. This is
particularly important for thin/lightweight materials.
……..
6.
Reporting of the result
7.
References
Bertelsen, N.H., 1984, Fugttransport målt med kopmetoder. Nordtest workshop, bagrund og
udviklingsområder. (Moisture transport measured with cup methods, Nordtest workshop,
background and further development issues). Byggeteknik, Teknologisk Institut, Denmark, (In
Danish).
Greenspan (1977), Humidity Fixed Points of Binary Aqeous Solutions. Journal of Research of the
National Bureau of Standards – A. Physics and Chemistry, 81A (1), pp.89-96.
Nyqvist (1983), Saturated Salt Solutions for Maintaining Specified Relative Humidities,
International Journal of Pharmaceutical Technology and Product Manufacture, 4(2), pp.47-48.
Appendix 4
Nordic Building Physics Symposium, 2005
Reykjavik, June 13-15, 2005
--- ABSTRACT --- (draft 14.09.2004)
Moisture Buffer Value of Materials in Buildings
Carsten Rode, Technical University of Denmark
Ruut Peuhkuri, Technical University of Denmark
Kurt Kielsgaard Hansen, Technical University of Denmark
Berit Time, Norwegian Building Research Institute
Kaisa Svennberg, Lund Institute of Technology
Jesper Arfvidsson, Lund Institute of Technology
Tuomo Ojanen, VTT Technical Research Centre of Finland
Building materials and furnishing used in contact with indoor air have an effect to moderate the
variations of indoor humidity seen in occupied buildings. Thus, very low humidity can be avoided
in winter, as well as can high indoor humidity in summer and during high occupancy loads. This
way, materials can be used as a passive means of establishing indoor climatic conditions, which are
comfortable for human occupancy, or for safe storing of artefacts which are sensible to humidity
variation.
But so far there has been a lack of a standardized figure to characterize the moisture buffering
ability of materials. It has been the objective of a recent (ongoing until mid-2005) Nordic project to
come up with such a definition, and to declare it in the form of a NORDTEST method. Apart from
the definition of the term Moisture Buffer Value, there will also be a declaration of a test protocol
which expresses how materials should be tested. Finally as a part of the project, some round robin
tests will be carried out on various typical building materials.
The paper will give an account on the definition of the Moisture Buffer Value, it will outline the
content of the test protocol, and it will give some examples of results from the round robin tests.