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A numerical model of a solar wall (SW) with transparent insulation (TI) is proposed in this article. The model is based on the finite-difference method and thermal conductivity equation, with a heat source term for the absorber. Using this model, the energy efficiency of a solar wall with transparent insulation (SW-TI) with honeycomb insulation made of modified cellulose acetate was analyzed in the case of different climatic conditions prevailing in Poland, different orientations of the envelope, and different insulation thicknesses. Simulations were carried out throughout the whole heating period. Monthly energy balances and temperature distributions for the analyzed envelopes at individual moments of the heating period are the basic results of the simulations. It was found that the use of 108 and 88 mm thick insulation was the most recommended in the considered temperate climate. Placing transparent insulation on a wall with an eastern or western orientation caused the annual heat balance of the envelope to decrease by 24–31% in relation to the value of this balance in the case of a southern orientation. The monthly heat balances obtained using the proposed model give results consistent with the method of calculating heat gains for opaque building envelopes with transparent insulation included in the PN-EN ISO 13790:2008 standard.

Effective thermal conductivity of porous building materials is a very important parameter particularly in the thermal performance analysis of building envelopes. In this part of the paper the selected models of effective thermal conductivity of 2-phase porous building materials fully filled with air or water are analyzed and verified.The calculated values from models are compared with measured data from literature and recommendations for selecting models are provided.

Keywords:Theory of mixture Thermodynamic potentials Chemical potential tensor Enthalpy tensor Free energy tensor Internal energy tensor a b s t r a c t Four thermodynamic tensorial quantities, equivalents of the thermodynamic potentials, namely the chemical potential tensor, the tensor of enthalpy, the tensor of free energy and the tensor of internal energy are presented. The last three of them are proposed in this paper and connections between all of these tensors are derived. The tensorial forms of the thermodynamic potentials are expressed in terms of four possible pairs of independent state variables. A set of sixteen alternative expressions, four for each tensorial form of the thermodynamic potential are derived and their importance discussed.

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