AIVC - Air Infiltration and Ventilation Centre

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Inferring ventilation and moisture release rates from field psychrometric data only using system identification techniques.

System identification techniques are developed allowing room or building ventilation and moisture release rates to be inferred from field psychrometric data only. The techniques have been developed primarily to allow the surveying of a large number of houses so that statistical properties can be compiled, in which high accuracy of individual results is not required. This system provides an alternative to PFT tubes, with some economic advantages.

Moisture conditions of outdoor air ventilated crawl spaces in apartment buildings in a cold climate.

The effects of air change and ground covers on crawl space moisture balance in a cold climate are discussed in this paper. The objectives were to assess the suitability of outdoor air-ventilation in the crawl spaces of apartment buildings, to determine the optimum air change rate with and without ground covers, and the effect of the ground covers' thermal insulation on moisture behaviour. Measured data from the test building was used to develop the crawl space model in a modular simulation environment, where the parametric simulations were carried out.

Moisture damage in schools - symptoms and indoor air microbes.

The association of moisture damages of school buildings with microbial indoor air quality and health status of school children was studied. To determine the association the school buildings (N=32) were divided into the moisture damaged (index) and non-damaged (reference) schools according to technical inspection data. Children's health surveys were made by questionnaires. Microbes were determined from indoor air of school buildings using a six-stage impactor. Children in the index schools reported more respiratory symptoms compared to children in the reference schools.

Moisture in the roofs of cold storage buildings.

The low-slope roofs of ten cold storage buildings in the Dallas area were examined visually and thermo graphically (Tobiasson and Korhonen 1985) from above and below. Two inch (51 mm) diameter cores were taken to verify infrared findings and to determine moisture contents for estimating wet thermal resistances (Tobiasson et al. 1991 ). Twelve inch (0.3 m) square specimens of many of the insulations were removed for laboratory studies of their thermal properties and structure.

Drainage, ventilation drying, and enclosure performance.

This paper explores the influence and role of both drainage and ventilation drying on the ability of enclosure assemblies to control moisture. Drainage is often the most direct method of removing water from within a wall (i.e., from exfiltration condensation or rain penetration), but it is often not sufficient to provide moisture control. Design approaches that rely solely on drainage to remove moisture from behind the outer layers or cladding ignore the significant quantities of moisture that can be stored in the outer layers of most enclosure walls.

Mouldy houses - building science lessons from the Wallaceburg Project.

Thirty-nine houses with high levels of biologically active contaminants in Wallace burg, Canada, and twenty houses with low levels of biologically active contaminants, were subjected to field inspections and testing, monitoring of indoor environmental conditions, and simulation to predict the condensation formation potential in winter. Occupant health was evaluated through questionnaires and blood sampling from an index child (closest to age ten) for analyses of T-lymphocyte and B-lymphocyte structure.

On ventilation needs - towards demand controlled ventilation in dwellings.

Ventilation needs in dwellings must be determined on the basis of both requirements to theindoor air quality and necessary control of moisture conditions. As a first step towardsdevelopment of energy efficient ventilation strategies for demand controlled ventilation infuture dwellings theoretical analyses comprising a literature study and mathematicalsimulations have been carried out.

Hygrothermal performance of attics.


Risk of indoor condensation related to thermal insulation standards.

Condensation phenomena on internal surfaces of buildings are becoming recurrent eventualities in contemporary buildings, particularly in residential buildings. Despite the general belief, this accumulation of water on walls is not mainly due to mass migration from outdoor to indoor, but to a modification of behavioural approaches of people, especially referring to the preferred air temperature.