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DTU Contribution to IEA Annex 41, MOIST-ENG

DTU's Experience and Experimental Facilities

• History• Projects• Ph.D.-projects• Models• Experimental

facilitiesAssistant Prof. Ruut PeuhkuriPh.D. student Lone HedegaardAssociate Prof. Carsten Rode

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History Building envelope research

• a long tradition of research and development of highly insulated building envelopes without moisture problems.

• research in flat roof constructions �moisture transported by convection could be much more important than diffusion

� the development of the Hygrodiode membrane - a vapour retarder

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Projects1. Participation in former IEA ECBCS Annexes

– Annex 19 Low Slope Roof Systems – Annex 24 Heat, Air and Moisture Transport in

Insulated Envelope Parts – Annex 32 Integral Building Envelope Performance

Assessment2. Since 1998 a member of DTU’s International

Centre for Indoor Environment and Energy3. Danish Research Council: Hygrothermal

Performance of Whole Buildings– fundamental and practical knowledge on HAM

conditions in "complete" buildings

4. NORDTEST Workshop on Moisture Buffering, August 2003

– development of a "NORDTEST Method" with a definition and associated measuring method(s).

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g Ph.D.-projectsMoisture buffering materials (Tim Padfield)

• use of building materials to moderate indoor relative humidity

• a small test chamber (about 0.5 m3) in which the humidity could be measured when vapour was injected or withdrawn

• conventional building materials and some new organic materials

• Important factors for buffering: hygroscopicity and vapour permeability

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g Ph.D.-projectsMoisture Dynamics in Building Envelopes

(Ruut Peuhkuri)

• Non-Fickian behaviour• Non-isothermal moisture

transfer

• Insulation materials: rock wool, glass wool, cellulose, perlite, flax, wool, ACC

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g Ph.D.-projectsHygrothermal Microclimate on Interior Surfaces

(Lone Hedegaard)

Quantify moisturetransfer by•Experimental work

•Simulation sub-model, CFD

Means•Case study

•PIV and full-scale

•CFD

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ModelsMATCH – simulation tool for building envelopes

• Developed in a Ph.D. project at DTU• Available to researchers and

practitioners• Hourly, transient calculations for multi-

layered constructions

• Outdoor climate: a weather file (Test Reference Year or similar) with information of the outdoor temperature, humidity, solar radiation and wind speed.

• MATCH has been under intermittent development over the years. The current version: www.match-box.dk

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ModelsBSim model – simulation tool for whole buildings

• Hygrothermal conditions for "whole" buildings - must know the thermal conditions first

• BES tools exist - large efforts put into their development

• DTU co-operation with the Danish Building and Urban Research institute about their tool: BSim

• Probably among the first models to provide this kind of functionality to end-users.

• More information about BSim: www.bsim.dk

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g Experimental facilitiesHygrothermal Standard Material Properties

• Thermal conductivity• Water vapour permeability• Sorption curves• Suction curves• X-ray equipment

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g Experimental facilitiesNon-standard methods

• one-dimensional exposure• rapid RH changes

2. Isothermal or non-isothermal dynamic measurements (Megacup)

1. Isothermal dynamic measurements (Small climate chambers)

• prototype apparatus • dynamic changes of

humidity and temperature (40-95% RH and 10-30ºC)

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Experimental facilitiesPASSYS Cells

• airtight and highly insulated office size steel box– vapour tight and non-absorbing interior

surfaces– sensors measuring both outdoor climate and

indoor conditions

– Evaporation imitates an inhabited room

– Dehumidification imitates ventilation

• control of condensation and evaporation

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DTU Contribution to IEA Annex 41, MOIST-ENGDTU's Experience and Experimental Facilities

• History: Research on building envelope• Projects

– Participation in former Annexes– International Centre for Indoor Environment and Energy– Danish Technical Research Council Project:

Hygrothermal Performance of Whole Buildings– NORDTEST Workshop on Moisture Buffering

• Ph.D.-projects– Moisture buffering materials– Moisture Dynamics in Building Envelopes– Hygrothermal Microclimate on Interior Surfaces of the Building Envelope

• Models– MATCH model – simulation tool for building envelopes– BSim model – simulation tool for whole buildings

• Experimental facilities– Measurements of Hygrothermal Material Properties– Isothermal dynamic measurements (Small climate chambers)– Isothermal and non-isothermal dynamic measurements (Megacup)– PASSYS Cells

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ProjectsParticipation in former Annexes

DTU was an active participant in IEA ECBCS Annexes:• Annex 19 Low Slope Roof Systems• Annex 24 Heat, Air and Moisture Transport in Insulated Envelope

Parts. DTU contributed to all five subtasks, but mainly to:– Subtask 1 on Model and Algorithm Development– Subtask 2 on Indoor and Outdoor Environmental Conditions

• Annex 32 Integral Building Envelope Performance Assessment--------------------------------------------

DTU has been a strong proponent for IEA Annex 41 by arranging meetings about it at:

• Buildings VIII, Dec. 2001• 6th Symposium on Building Physics in the Nordic Countries, June 2002• 11th International Symposium for Building Physics, September 2002

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• The group has since 1998 also been a member of DTU’s International Centre for Indoor Environment and Energy (Prof. Fanger), www.ie.dtu.dk

• Many problems in indoor climate are related to the humidity of indoor air or to problems of damp buildings --> The purpose of the research is to establish a proper knowledge about the humidity conditions in buildings

• This is done by:– climate chamber tests (PASSYS Cells), – development of models for the integrated hygrothermal

performance of buildings.

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ProjectsHygrothermal Performance of Whole Buildings

Purpose: To establish fundamental and practic knowledge on heat, air and moisture conditions in "complete" buildings with their indoor spaces, exterior and interior constructions and materials, occupants, and technical systems.

The project runs for three years (May 2003-06), and is the main supporting activity for the participation in IEA Annex 41.

http://www.byg.dtu.dk/proj_webs/hygrotherm/index_hygro.htmSubtasks:• Task 1: Material characterisation• Task 2: Indoor air/material interactions• Task 3: Analysis of hygrothermal microclimatic conditions• Task 4: Modelling of whole building hygrothermal performance• Task 5: Impact analysis: Indoor air quality, productivity, durability,

energy consumption

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ProjectsNORDTEST Workshop on Moisture Buffering

• August 2003: Workshop at DTU on

Moisture Buffer Capacity• Lack of stringent definition of moisture buffer capacity • How important is it for the humidity conditions of

buildings?• 30 participating researchers

• A follow-up project has been proposed:• Will develop a "NORDTEST Method" with a definition

and associated measuring method(s).

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ModelsMATCH – simulation tool for building envelopes

• International research in the 1980'es (and earlier) led to the development of transient computer models for combined heat and moisture transport in building constructions.

• The MATCH model was developed in a Ph.D. project at DTU (1987-90) and was probably the first of this kind of computer models that was made available also to other researchers and to practitioners (C.R. Pedersen 1990, Combined Heat and Moisture Transfer in Building Constructions).

• Hourly, transient calculations for multi-layered constructions that separate a prescribed indoor climate from an outdoor climate.

• This outdoor climate comes from a weather file (Test Reference Year or similar) with information of the outdoor temperature, humidity, solar radiation and wind speed.

• MATCH has been under intermittent development over the years. Information about the current version is available on the homepage: www.match-box.dk

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ModelsBSim model – simulation tool for whole buildings

• Hygrothermal conditions for "whole" buildings - must know the thermal conditions first

• BES tools exist - large efforts put into their development

• DTU co-operation with the Danish Building and Urban Researchinstitute about their tool: BSim

• Probably among the first models to provide this kind of functionality to end-users.

• More information about BSim: www.bsim.dk

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Experimental facilitiesMeasurements of Hygrothermal Material Properties

The laboratories of DTU have some good facilities for measurement of standard hygrothermal properties of building materials:

• Thermal conductivity• Water vapour permeability• Sorption curves• Suction curves• X-ray equipment

Some years ago (1986), Kurt K. Hansen made a rather well known and useful compilation of sorption isotherms (Based on measurements from literature)

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g Experimental facilitiesIsothermal dynamic measurements

(Small climate chambers)• A geometrically well-defined sample

can be exposed to a one-dimensional combined moisture transport and sorption process in these climate chambers.

• The sample is continuously attached to a balance and positioned in a climate chamber, whose climate is automatically controlled and which maintains the desired temperature and relative humidity with a given accuracy.

• The experimental procedure usually involves a series of rapid changes in the chamber's relative humidity.

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g Experimental facilitiesIsothermal and non-isothermal dynamic

measurements (Megacup)• Prototype apparatus to measure water vapour

transmission through materials under dynamic and non-isothermal conditions

• Can also measure the moisture buffer effect of a material in response to dynamic changes of humidity with a small reservoir

• Cylindrical well made of stainless steel• Inner dimensions: 793 mm (diameter) and 500

mm (depth)• The test specimen can be suspended

horizontally on the top of the chamber or placed inside this airtight well.

• The moisture flux to and from the sample is determined by weighing the mass of a small open water container with given intervals.

• Inside climate: Constant or oscillating between 10-30ºC and 40-95% RH

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Experimental facilitiesPASSYS Cells

• Very airtight and highly insulated steel box with indoor area 13.8 m2, and room height 2.75 m

• Inside wall makes a vapour tight and non-absorbing interior surface

• The cell is instrumented with sensors for measuring both the outdoor climate and the indoor conditions

• The control system makes it possible to control the rates of condensation and evaporation according to a predefined schedule:

– Evaporation of water imitates the production of humidity in an inhabited room.

– Dehumidification makes it possible to imitate the removal of humidity from the room such as by ventilation