AIVC - Air Infiltration and Ventilation Centre

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Towards the zero-energy house.

Concentrates on low energy housing construction in Scandinavia, and Sweden in particular, where typical new detached houses with a floor area of 140 m2 now use less energy for space heating than water heating. 

Humidity, condensation and ventilation in houses.

Contains articles on rain penetration and moisture damage in residential construction, moisture sources in houses, control of surface and concealed condensation, and ventilation of houses. Illustrates the various types of condensation problems that may occur, explains the active processes involved in some of these problems and discusses in detail the principal factors surrounding these phenomena i.e. sources of moisture, choice of construction detail, and current ventilation practice.

Humidity in buildings and thermal bridges. Wohnfeuchte und warmebrucken.

The installation of much tighter windows has led to reduced rates of natural ventilation in German dwellings. This has resulted in increased indoor air humidity and condensation formation on the inner surfaces of external building elements with thermal bridges. Notes the areas most at risk from condensation and mould, in particular corners of outside walls and along the ceiling angle.

Condensation prevention: loft ventilation - a discussion paper.

This is the third item in a series on methods for predicting condensation risks within structures. It answers criticisms made of the method described in NO 1729, on the basis that the method does not give the same answers, nor does it take account of the effect of the occurrence of condensation on the vapour pressure gradient within the structure, as does the graphical method described in NO 1728.

Condensation: prevention better than cure.

Describes in detail a computer-based technique for predicting the risk of condensation occurring in building structures. The technique not only indicates the position at which condensation is likely to occur, but also puts a figure on the risk of decay in timber within the structure. In the case of ventilated roofs or walls it gives the minimum sizes for ventilation openings.

Interstitial condensation. Assessment of risk.

Sets out the mathematical techniques for determining 1 the most likely position of the condensation plane, 2 the limiting humidity at a given room temperature, below which condensation will not accumulate within the structure, 3 the rate at which condensate is likely to accumulate at the plane if the relative humidity within the structure persistently exceeds the limiting humidity. The technique is a graphical one and assumes that the conditions chosen for the purpose of the analysis remain constant indefinitely, a condition known as "steady state".

The influence of air leakage on the condensation behaviour of lightweight roofs.

The theoretical background, admittance measurements and experimental work on interstitial condensation in lightweight roofs caused by air leakages is discussed. Describes a theoretical model of condensation behaviour taking into account moisture transfer by air flow as well as diffusion. Gives the air flow admittance for various roofing materials, ceiling systems and different roof-sections. Experimental results agreed well with the theoretical model.

Vapor barrier paints.

This report addresses the factors causing water vapour problems and provides insights into the solutions available with particular emphasis on vapour barrier paints. Concludes that 1. moisture flow in structures is a dynamic, systemic process of multiple variables, and therefore requires an integrated approach for management, 2. retrofit applications offer an entirely different set of physical and economic considerations than are found in new construction and therefore require a different approach, 3.

Steady-state one-dimensional water vapor movement by diffusion and convection in a multilayered wall.

Current moisture analysis methods for walls ignore air leakage effects or are not directly applicable to multilayered walls. Mathematical equations were developed for water vapour flow, vapour pressures, and moisture accumulation under steady state conditions with homogeneous one dimensional air flow through a multilayered wall.

Reduction of air infiltration and the development of controlled mechanical ventilation in France.

Since 1974 the french Authorities have insisted on energy being saved in all buildings. There was very strong pressure on manufacturers to obtain better sealed window frames . In practise less than two or three meters cubed per hour at a pressure of ten pascals penetrates. Also television campaigns have insisted on weather stripping all windows and window frames in all old buildings. The result of these campaigns is that all buildings with no or natural ventilation systems actually have indoor condensation problems.