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    HAM: MATCH

    1D HAM model Match

    MATCH, Moisture and Temperature Calculations for Constructions of Hygroscopic Materials, is a computer model for calculation of combined heat and moisture transport in composite building structures. The model was developed originally in a Ph.D. project at the Thermal Insulation Laboratory (now part of the Department of Buildings and Energy) at the Technical University of Denmark (Rode Pedersen, 1990).

    The program has been validated by comparison with experimental data obtained in the laboratory and in field studies. Such comparisons can be found in the Ph.D. thesis (Rode Pedersen, 1990), and for instance in a paper by Rode and Burch, (1995).

    The program has been used in international research projects such as IEA Annex 24 on Heat Air and Moisture Transport in Insulated Envelope Parts - HAMTIE, http://www.ecbcs.org/annex24.html, Hens 1996). It is still used in various Danish and international research projects (e.g. http://www.ornl.gov/roofs+walls/codes/index.html), in teaching and by consulting engineers and manufacturers of building products.

    Applicability of the MATCH program

    Calculation of moisture transport in and through building constructions has so far been based on steady state methods which do not consider the hygroscopic capacity of building materials. The hygroscopicity causes the materials to absorb, retain or release moisture - even when they are in equilibrium with non-saturated air.

    The PC-based numerical model, calculates the temperature and moisture profiles transiently, i.e. time dependent by considering the thermal and hygroscopic capacities. By dividing the time into small steps, it is possible to take into account the effect when constructions are exposed to short, intensive temperature gradients, such as when they are exposed to solar radiation.

    Interactive Input

    The most important user task is to set up the input for the calculation. Such input describes the construction, its environment and the conditions for the calculation. A pre-processor, PREMATCH, helps the user in setting up the input for MATCH correctly. In PREMATCH, there are default values for all parameters. Furthermore, it is possible to:

    - Get an overview of previous projects

    - Correct old input files

    - Select materials from a data base with material properties.

    Graphical Output

    The calculation results for temperature, vapor pressure, relative humidity and moisture content are continuously updated on the graphical display while the calculation is carried out.

    Selected variables like those mentioned above, and values of the heat and moisture flows, can be retrieved again after the calculation by the graphical post-processor, MATCH GRAPH. From this program, the graphs can be printed, and may serve as final documentation of the calculation.

    Principle of the Calculation

    MATCH uses a Finite Control Volume method (FCV) to calculate the transient evolution of both the thermal and the moisture related variables. The layers of the construction are divided into smaller control volumes, and the time into steps of 1 hour or less. For each volume and time step, the flows of heat and moisture in and out of the volume are calculated. The difference between the amounts flowing in and out are stored or released from the volume.

    The moisture transport is described by vapour diffusion according to Fick's law. The driving vapour pressures are found from the moisture content of the layers and the sorption curves of the materials.

    The transfer of latent heat by evaporation and subsequent condensation in the construction is calculated as a correction to the usual, conductive heat transfer.

    Furthermore, it is possible to calculate the liquid moisture transport - to the extent the material parameters for this kind of transport are known.

    Test Reference Years

    In order to describe the climate in the outdoor surroundings of a construction, a test reference year (TRY) of the particular location is used. A TRY comprises such climatic parameters as temperature, humidity, solar radiation and wind speed. Test reference years, which are available for many locations in Europe and North America, consist of selected, representative periods of actually measured data that have been put together to form a whole year.

    Alternatively, MATCH may read files which contain data that represents special kinds of "outdoor climates" - for instance on the external side of a basement wall. Such files may also contain values that have actually been measured.

    Indoor Climate

    The indoor climate is described by values of temperature and either a relative humidity or a rate of moisture generation, which are indicated for one month at a time.

    Construction Types

    MATCH calculates the hygrothermal state of all constructions that are characterized by having a predominant 1-dimensional geometry, and where convective transports of heat and moisture have been eliminated. This will typically be constructions like walls and flat and sloped roofs which separate an indoor from an outdoor climate. Employing special climatic data, MATCH may also been used to describe the conditions in other indoor and outdoor constructions.

    Material Property Data Base

    MATCH has a data base which contains the thermal and moisture transport characteristics of about 70 materials. The many values for each material are assigned just by referring to the name of the material.

    Hardware Requirements

    MATCH runs on IBM-compatible PC's under the DOS environment. It can also be executed under MS Windows, Windows 95 and Windows NT.

    Literature

    Hens, H. Heat Air and Moisture Transport in Insulated Envelope Parts. Final Report. Labo Bouwfysica, Katholieke Universiteit, Leuven. 1996.

    Rode Pedersen, C. Combined Heat and Moisture Transfer in Building Constructions. Ph.D. Thesis. Report 214. Thermal Insulation Laboratory, Technical University of Denmark. 1990.

    Rode, C. and Burch, D. M. Emprical Validation of a Transient Computer Model for Combined Heat and Moisture Transfer. Thermal Performance of The Exterior Envelope of Buildings VI Conference. Dec. 4-8, 1995, Sheraton Sand Key Hotel, FL, USA. 1995




    More info of this article can be found on the web at: This link was checked on Dec. 2006http://www.ibe.dtu.dk/PROGRAMM/Match/Match.htm




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