Abstract
The thickness of the building insulation is calculated with the table values of the moisture of building materials, which is included in the regulatory documents with a margin. The study proposes the method for determining the thickness of the insulation layer using the values of operational moisture. To determine the operational moisture of materials, the equation based on the moisture potential is applied, the solution of which is sought using a discrete-continuum approach. The proposed equation makes it possible to determine the distribution of the moisture potential function in the wall enclosing structure. Thereafter, using the moisture potential scale, the distribution of mass moisture over the thickness of the enclosure for the period of maximum moisture accumulation is determined. The equation for determining the thickness of the insulation layer, in which the calculated value of the operational moisture is explicitly substituted, is derived. An algorithm for calculating the thickness of the insulation layer, taking into account the unsteady-state heat and moisture regime of the building envelope, is given. The application of the proposed method on a wall enclosing structure with insulation from expanded polystyrene boards is illustrated. It was found that the thickness of the insulation can be reduced by 26 mm from 120 mm to 94 mm while maintaining the reduced heat transfer resistance of the building wall. It is noted that the proposed method can be applied in the design of new wall enclosing structures.