The Equilibrium Moisture of Building Enclosures as Function of Calculated Climatic Parameters/Pastatų atitvarinių konstrukcijų nuostoviojo drėgnio priklausomybė nuo skaičiuojamųjų klimato parametrų

The climatic parameters influence the equilibrium moisture of building enclosures and their thermal insulating layers. This investigation seeks to find a quantitative correlation between these influence values. The enclosure equilibrium moisture content W 0 was expressed as the sum of two components: sorption moisture W s and thermal condensation moisture W t (formula 1). The coefficient η was introduced as the maintenance moist state criterion (formula 3), which depends on climatic conditions. It has been used for in-situ investigations of different enclosures (Fig 1) of dwelling houses as well as for damp and wet premises data [4–15]. The results (Fig 2, 3) show the dependence of equilibrium moisture on η. This dependence has been expressed by (4), where W t 0 is W t component due to thermal condensation when η=0. W t 0 is equal to 12,3% (vol) for ceramic and sand-lime, brick masonry as well as for porous concrete, expanded clay aggregate, slag fillings and is equal to 0,028% (vol) for rock wool products in traditional enclosures (Fig 1). The parameter α (7) was introduced for estimating cold season climate influence after mathematical statistical treatment of long-term climatic data [19]. It has been found (Table 1) that a may be adopted to be equal to 0,2 when the equilibrium moisture component due to thermal condensation has been calculated for Lithuanian climatic conditions. The possible equilibrium moisture of various building materials for enclosures has been evaluated by the proposed method and is given in Table 2. The data do not apply to expanded polystyrene, polyurethane foam and cellulose fibre because in-situ investigation data are absent for enclosures with these insulating materials. Table 2 shows that there are several distinctions in given values and corresponding values introduced in abrogated normative documents [25, 26] as well as corresponding corrections Δλw in valid documents [27] stipulated by additional moisture content of materials in enclosures. The correction value Δλw must be defined more precisely when thermal conductivity design values are calculated for enclosures with porous concrete or expanded clay aggregates.

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