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Publications in Scientific Journals:

P. Wegerer, T. Bednar:
"Hygrothermal performance of wooden beam heads in inside insulated walls considering air flows";
Energy procedia, 132 (2017), 652 - 657.



English abstract:
When planning an interior insulation for a building with existing wooden ceilings, the hygrothermal performance of the wooden
beamsī heads inside the masonry need special consideration. Because of airflows due to thermal differences in pressure, warm and
humid ambient air can penetrate the external construction components. Thus, condensation on the masonry surfaces resp. on the
wooden beam will occur, which may lead to high moisture content and finally to processes of decay. Especially when thermally
renovating a building using interior insulation the support areaīs temperature level during winter is lowered significantly. Therefore,
adequate airtightness of the inner shell is to be considered with such construction. At the same time, a certain degree of leakiness
must be assumed in the planning stage since 100% airtight constructions are not achievable in practice.
This paper will introduce a simulation model which takes into account convective hygrothermal processes in aerial spaces besides
simulating temperature and moisture in porous materials. Using the example of a three-dimensional model of a wooden beam head,
the influence of airflows will be shown. Damp permeation due to convection is going to be modeled by a condensation source at
the wooden beam headīs end. The amount of condensate occurring there is determined by the mass flow from the inside into the
construction as well as the temperature conditions on the surface. Furthermore, the size and set-up of the leakage between the
interior air and the ceiling cavity is important. The results show that the durability of the wooden beamsī heads heavily depends on
room air humidity and leakage size as well as the differences in pressure between the two aerial spaces. The resultsī assessment is
made by evaluating the risk for decay of the wooden components.

Keywords:
inside insulation; air flow; risk assessment; wooden beam head


"Official" electronic version of the publication (accessed through its Digital Object Identifier - DOI)
http://dx.doi.org/10.1016/j.egypro.2017.09.710


Created from the Publication Database of the Vienna University of Technology.