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Numerical modelling of unsteady humidity transport and accumulation in walls

The purpose of the work is the determination of unsteady variation of the moisture content in the walls. The mathematical model is based on humidity transport equations in porous media. The humidity transport takes place as a result of the presence of both moisture content and vapour pressure differences. Using the proposed mathematical model, a computer program was developed in EES (Engineering Equations Solver). Numerical simulations were made for an office room, considering interior walls containing a gypsum board layer.

Moisture transport in building materials with imperfect hydraulic contact interfaces

Based on the experimental results and predictions of a numerical model, the effects of uncertainty in estimation of imperfection of the interface on moisture transport were studied in the present study. It was found that, even though the imperfection of the interface varied with moisture content during the wetting process, the prediction using a constant resistance of the interface was close to that using an actual value.

Sufficiency of cleaning after repair of mold damage evaluated by microbiological methods

Constructional aspects and the use of school building had led to moisture and mold damages confirmed by microbiological analysis from material, surface and air samples. Cultivation methods were used to assess mesophilic fungi and actinobacteria. High concentrations of microbes (10 5 -10 6 cfu/g in different materials) were recovered from the samples. Microbes included great variety of moisture indicating species (e.g. Aspergillus versicolor, Trichoderma, Fusarium, Stachybotrys, Chaetomium, Streptomyces).

Interstitial condensation due to air leakage: A sensitivity analysis.

This paper presents an approach to evaluate the sensitivity of a roof design to condensation problems, given the uncertainty to achieve continuity of airtightness in practice. The approach consists of a repeated number of simulations with a 2D heat, air and vapour transfer model to predict the variation in roof moisture performance due to various discontinuities in roof geometry. The set of discontinuities is calibrated by comparing measuring data of roof airtightness to simulation results.

Displacement ventilation for room air moisture control in hot and humid climate

Few studies dealing with the effect of displacement ventilation on humidity gradient in a hot and humid region have been made . In this paper it is done with a case-study approach (measurements were made in a factory located in the Tropics). The results indicate that the humidity gradient is as significant as the temperature gradient..

A zonal model for predicting simultaneous heat and moisture transfer in buildings

A zonal model was developed to predict temperatures and moisture in a room taking into account the adsorption/desorption by building materials. Results show how adsorption/desorption influences the moisture field.

Observing Mother Nature in action: moisture problems in buildings in the southeast.

Presents a selection of moisture problems encountered in the south eastern USA. Discusses moisture in attics, moisture in floor cavities, moisture inside the house, hardwood floors with moisture problems, and vented crawlspaces.

Are unvented fireplaces too hot to handle?

Documents what some builders have said about problems with moisture, soot and IAQ in relation to unvented gas fireplaces. Unvented gas fireplaces have become popular recently in the US due to their low cost and flexibility in installation. However many building scientists and indoor air quality professionals have warned against their use because discharging combustion by products into the home invites serious moisture and IAQ problems.

Public housing breaks the mould. Part II: Veterans era housing.

Part 1 of this feature discussed the particular moisture and air quality related problems of midrise housing, and took a close look at two cases. This article analyses issues unique to 'Veterans Era Housing' (US housing built for World War II veterans during the 40s and 50s) and presents three cases where moisture problems were successfully addressed.

Moisture, building enclosures and mould.

Explores how water gets into a structure, why it doesn't leave, and how these architectural flaws become HVAC problems. States that mechanical engineers need to understand the roots of the problems in order to defend their work if IAQ becomes a problem once the building is occupied. The article reviews air control and pressurization, ventilation and humidity control and provides some resources to help expand the reader's knowledge of design and construction errors that lead to HVAC problems.