CORNER EFFECTS ON THE HYGROTHERMAL PERFORMANCE OF BUILDINGS

Multidimensional effects through porous building elements is barely explored in the literature due to many difficulties such as modeling complexity, computer run time, numerical convergence and highly moisture-dependent properties. Furthermore, when the multidimensional effect is considered, thermal bridges may play an important role on the hygrothermal building performance due to local increase of heat and mass flux densities. Therefore, in order to analyze the effects of building lower and upper corners, a multidimensional model has been developed to calculate the coupled heat, air and moisture transfer through building envelopes. For improving the discretized model numerical stability, the algebraic equations are simultaneously solved for the three driving potentials: temperature, vapor pressure and gas pressure gradients. In the results section, the coupling of the upper corner, wall, lower corner, ground and floor are analyzed for different boundary conditions in terms of temperature and relative humidity profiles, vapor flow and heat flux, showing the importance of a detailed hygrothermal analysis for accurately predicting building energy consumption, thermal comfort and mould growth risk.

[1]  Nathan Mendes,et al.  A building corner model for hygrothermal performance and mould growth risk analyses , 2009 .

[2]  Nathan Mendes,et al.  DOMUS 2.0: A WHOLE-BUILDING HYGROTHERMAL SIMULATION PROGRAM , 2003 .

[3]  Nathan Mendes,et al.  A new mathematical method to solve highly coupled equations of heat and mass transfer in porous media , 2002 .

[4]  S. Hassid,et al.  Thermal Bridges Across Multilayer Walls· An Integral Approach , 1990 .

[5]  T. Blomberg.  Heat conduction in two and three dimensions : computer modelling of building physics applications , 1996 .

[6]  E. Bender.  Numerical heat transfer and fluid flow. Von S. V. Patankar. Hemisphere Publishing Corporation, Washington – New York – London. McGraw Hill Book Company, New York 1980. 1. Aufl., 197 S., 76 Abb., geb., DM 71,90 , 1981 .

[7]  M. Deru.  Model for Ground-Coupled Heat and Moisture Transfer from Buildings , 2003 .

[8]  Piotr Narowski,et al.  MODELLING OF CONDUCTION TRANSFER FUNCTIONS FOR TYPICAL THERMAL BRIDGES IDENTIFIED IN BIM DATA , 2011 .

[9]  B. R. Anderson.  The effect of edge insulation on the steady-state heat loss through a slab-on-ground floor , 1993 .

[10]  Hartwig M. Künzel,et al.  Hygrothermal Properties and Behaviour of Concrete , 2008 .

[11]  M. Krarti.  Steady-state heat transfer from horizontally insulated slabs , 1993 .

[12]  Nathan Mendes,et al.  Unsteady Combined Heat and Moisture Transfer in Unsaturated Porous Soils , 2005 .

[13]  Carl-Eric Hagentoft,et al.  Heat loss to the ground from a building—II. Slab on the ground , 1991 .