condensation and evaporation

"The physics of condensation within the building envelope is quite complex and quantification of the phenomenon using mathematical computer models is the subject of some research today. The basic factors which affect the process have been known for some time and include but are not restricted to the following: indoor and outdoor temperatures, material properties such as air and vapour permeability, building envelope construction details, indoor relative humidity and indoor/outdoor air pressure differences. Condensation on or within the building envelope occurs when water vapour is transported to a location that is at or below the dewpoint temperature. Early researchers believed that the primary driving force in this transport was diffusion, a process dependent on vapour concentration differences and materialsˇŻ resistance to vapour flow. This idea spawned the use of a ˇ®vapour barrierˇŻ in the building envelope. Researchers now realize that while vapour diffusion can be a factor in some situations, the major reason for the amount of condensation in the construction of walls during the colder seasons is the outbound mass flow of moisture-laden air through the building envelope due to air leakage.

There are three separate air pressure loads across the building envelope which cause air leakage. Wind, stack or chimney effect and mechanical pressurization have been documented in papers and the Canadian Building Digests produced by the National Research Council of Canada (NRC). William Rose provided an excellent summary of the history of condensation problems and ventilation requirements in attics in a paper presented to Thermal Envelope VI Conference (Rose 1995). Problems still may occur in some buildings having high relative humidity where even a small amount of air could result in moisture being transported into the building envelope construction. Older buildings where the interior environment is changed to provide humidity may also experience problems they never had. .."

CBD

"240 of the 250 Canadian Building Digests published between 1960 and 1990 by NRC's Institute for Research in Construction. The topics reflect the diversity of the industry and cover virtually every aspect of design and construction in Canada."




Detec Systems - monitoring of hidden moisture in envelope of buildigns

Detec Systems provides automated, cost effective monitoring of buildings to detect and locate moisture intrusions and internal flooding. This unique service protects property owners against the destructive effects of hidden water within the envelope




IEA Annex 14: Condensation and Energy

"provided architects, building owners, practitioners as well as researchers, with a better knowledge and understanding of the physical background of these phenomena (critical) conditions for mould growth, material characteristics related to the problems, it has also provided them with better computation models taking air, heat and moisture transfer into account in order to predict properly the phenomena of surface condensation and possible solutions to avoid it."

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A critical review on equations employed for the calculation of the evaporation rate from free water surfaces , by Sartori, E., 2000

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Analysis of the evaporation coefficient and the condensation coefficient of water, by Marek, R. and Straub, J., 2001

IEA Annex 14

Annex XIV: Condensation and Energy. Volume 2: Guidelines & Practice and Volume 3: Catalog of Material Properties, by IEA, 1990

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CFD prediction of surface condensation on walls and its experimental validation, by Liu, J., Aizawa, H. and Yoshino, H., 2004

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Comparative studies on the water evaporation rate from a wetted surface and that from a free water surface, by Tang, R. and Etzion, Y., 2004

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Computer simulation of window condensation potential, by McGowan, A. G., Wright, J. L., 1998

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Condensation potential in high thermal performance walls -- cold winter climate, by Sherwood, G. E., 1983

condensation

Condensation potential in high thermal performance walls -- cold winter climate, by Sherwood, G. E., 1983

prevention and solution

Condensation problems in your house: prevention and solution, by Anderson, L. O. and G. E. Sherwood, 1974

risk analysis

Condensation risk assessment, by Janssens, A. and H. Hens, 1998

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Definition of two-dimensional condensation via BEM, using the Glaser method approach, by Sim?es, Branco, B. and A. Tadeu, 2002

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Design parameters used to avoid interstitial condensation for a range of climates, by Sanders, C. H., 1995

condensation in wood-frame house

Durability of energy-efficient wood-frame houses, by Smulski, S., 1999

discussion

Dynamic buffer zone - DBZ, by Makepeace, C.B., R. Ogle, and R. Nelson, 1999

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Evaluation of available correlations for rate of evaporation from undisturbed water pools to quiet air , by Shah, M. M., 2002

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Evaporation coefficient of water: a review, by Eames, I. W., Marr, N. J. and Sabir, H., 1997

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Free and forced convection effects on evaporation, by Sill, B. L., 1983

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Free evaporation into air of water from a free horizontal quiet surface, by Boelter, L. M. K., Gordon, H. S. and Griffin, J. R., 1946

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Heat and moisture transport with internal condensation in a fibrous insulation slab with impermeable boundary, by Couvillion, R. J. and Hawisa, J. S., 1993

mold and condensation

Humidity and development of mold on internal surfaces of building walls, by Sato, N., Vittorino, F. and Brazolin, S., 2000

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IEA Annex 14: Condensation and Energy, by Hens, H., 1992

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Interfacial mass and heat transfer during evaporation. I. An experimental technique and some results with a clean water surface , by Navon, U. and Fenn, J. B., 1971

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Interstitial condensation due to air leakage: a sensitivity analysis, by Hens, J. A. and H. Hens, 2003

in thermal bridges for design criteria

Moisture condensation in thermal bridges. Establishing design criteria, by Aroso, M., H., 1995

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Novel method for measuring water evaporation into still air , by Pauker, M. T., Tang, D., Jeter, S. M. and Abdel-khalik, S. I., 1998

exterior wall, field

On-site exterior wall monitoring methods for air leakage, condensation and rain penetration control problems, by Quirouette, R., 1999

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Reliable control of interstitial condensation in lightweight roof systems, calculation and assessment methods, by Janssens, A., 1998

risk

Risk of indoor condensation related to thermal insulation standards, by Ponterio, L., Rizzo, G., Rodono, G., Scaccianoce, G., 1999

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Surface temperatures of window specimens: infrared thermography laboratory measurements, by Griffith, B.T., H. Goudey and D. Arasteh, 2002

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The influence of various condensation phenomena on the indoor cooling by cold walls radiation technique: the case of quality of air, by Decamps, E., A., Royer, G., Queneudec, M. and J. R. Givri, 1995

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The ratio of heat losses by conduction and by evaporation from any water surface, by Bowen, I. S., 1926

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Use of statistics for prediction of risk for condensation in a wall construction cold walls radiation technique: the case of quality of air, by Nielsen, A., 1995

in porous material

Vapour condensation and moisture accumulation in porous building wall, by Wyrwa, J. and Marynowicz, A., 2002

condensation in built house

Ventilation, humidity, and condensation in manufactured houses during winter, by TenWolde, A., 1994

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Voluntary test method for thermal transmittance and condensation resistance of windows, doors and glazed wall sections, by AAMA, 1998