Negative pressure inside a building may create adverse or dangerous conditions. Discusses when make-up air is necessary, how need is determined, and how much make-up, with examples.
Complaints related to moisture problems in houses which had been air sealed, led to a study of indoor air quality in 20 weatherized demonstration homes in the Cambridge, Ontario area.
Roof space ventilation is necessary to evacuate water vapour to avoid condensation and to conserve the wooden roof supports. It has been affected by 1. increased insulation, 2. snow screens fitted under the roof, 3. increased humidity due to
Distinguishes two categories of leaks in buildings for cold storage. Thermal leaks through parts of the construction with poor thermal insulation and air leaks through openings in the walls allowing a more or less free flow of air. Outlines principles of infrared radiation and thermography. Discusses applications for both types of leaks. Under the conditions of high emissivity of the surface to be studied, and absence of local heating or cooling (sun,wind, rain), thermography is an effective method for the detection of thermalleaks and a powerful tool for localizing air leaks.
Deals with a code providing directives for design and construction of cold stores, drafted by the Foundation for Development of Refrigeration Technique (Stiftung Ontwikkeling Koeltechniek). Gives threshold values for admissible pressure difference and admissible measure of non-tightness, and values forthe required pressure equalizing opening, depending on nature and size of the cold room.
Discusses the effects of air infiltration and air change rate on temperature and humidity of indoor air. Attempts to quantify the relationship between surface temperature, thermal bridges, thermal resistance and indoor climate.
Retrofitting for air infiltration is undertaken for two principal reasons, to provide greater comfort and to save energy. Qualitative and quantitative measurement of air penetration is an essential prerequisite for planning anefficient retrofit for air infiltration. Describes methods of measurement with two examples of single family houses in sheltered and exposed locations.
Using meteorological and physical data, a model simulating pressure and air mass flow distribution in buildings was produced using the method of non-linear networks. It was used to study wind and buoyancy effects on mechanically ventilated buildings. Contents include: natural ventilation in high rise buildings with and without air-handling equipment, a study of a hospital, and calculation of the annual heat load for ventilation.
A previous paper analysed a mathematical model of a non-condensing cavity. This paper extends the analysis of the first paper to analyse the seasonal moisture behaviour of a condensing building cavity. Climate statistics are used to calculate the duration of the winter wet-up period, and a rate of condensation formula is integrated to give total winter condensation. Although engineering design calculations cannot yet be attempted, some illustrative examples are given based on field data. The results give preliminary verification of the model analysed in both papers.
This paper, the first of two, presents a conceptual model of moisture concentrations in a building cavity. The model is comprehensive and general considering air infiltration, vapour diffusion and material hygroscopicity under non-steady state conditions. The resulting linearised coupled differential equations are analytically solved to study the case of long term cavity moisture behaviour. Dimensionless parameters and algebraic formulae are presented describing all important moisture performance parameters for a non-condensing cavity.
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