English

Much disparity exists on the numerical efficiency and accuracy of different potentials for moisture transfer in building materials, with various implicit claims but no actual corroboration. This paper aims at providing such evidence by comparing the numerical efficiency and accuracy of capillary pressure, relative humidity and -log(-capillary pressure) for a suite of benchmark simulations.  The study shows that capillary pressure and relative humidity outperform -log(-capillary pres-sure), as the latter is plagued by its highly non-linear moisture capacity near saturation.

New links between parametric design software, energy simulation tools, and optimization algorithms allow for the customization of individual building components or whole building form in order to reduce anticipated energy use. These optimization methods are of particular interest in studying design problems where an energy conserving measure may act beneficially in one season but detrimentally in another if not properly sized, such as a static shading device.

Over the recent years more effort has been given to air tightness of public buildings such as hospitals. The demand for well insulated buildings increases the importance for low infiltration air rates and thus the air tightness becomes more important. Besides, air infiltration is a quantitative way to put into requirements for the tenders to fulfill.  In this work we describe field measurement of air-tightness on site in early stage of production, as well as field measurement of a whole floor in a hospital building.

Infrared thermography is an interesting technique that is often used for qualitative assessment of the building envelope. The method allows to detect construction deficiencies e.g. thermal bridges, moisture problems, incomplete blown-in retrofit insulation of cavity walls, wind washing in insulation layers etc. in a very fast way. Another application is the use of infrared thermography in combination with pressurization tests  in order to detect air leakages through the building envelope.

Because of temperature-based uplift within the building and the impact of wind on the building, airtightness measurements of high buildings are especially challenging. Temperature differentials between the building interior and the exterior with particularly high buildings can lead to excessively high baseline pressure differentials on the building envelope while the impact of wind can cause their extreme fluctuation, both of which may have a negative effect on the measurement. 

In this paper we present a series of leakage tests on extremely airtight dwellings (ACH50 < 0.6 upon completion) in which the durability of the airtightness and the measurement uncertainty involved are assessed. In literature, repeatability and reproducibility issues have been discussed by several authors, along with influences of weather. It remains unclear, however, to what extent the available uncertainty intervals are relative or absolute.

This paper gives an overview of the work undertaken within CEN TC 156 WG 3 dealing with ductwork for ventilation in buildings.