Seasonal Variations in Indoor Radon Concentration and Comparison Between the Energy-Efficient/ Passive House and Traditional House

Croatia has a diverse climate due to its geographical position, which spans from the Pannonian Plains in the east, over the mountainous central part of Lika and Gorski kotar to the Adriatic Sea in the south-west. Hence, different types of climates can be found in Croatia (continental, mountain and Mediterranean) depending on the region. To understand the influence of seasons on variations of indoor radon concentrations, solid state nuclear track-etched strippable detectors (Kodak LR115 type II from Dosirad) were exposed in 14 chosen dwellings in Croatia. In every moment, there are 3 radon detectors at every location: one is exposed for 3 months (within the climatic seasons), the other for 6 months (climatological seasons winter-spring or summer-autumn, respectively) and the third detector for the whole year. In this case study paper, specific cases related to different types of house construction are presented. The observed seasonal indoor radon variations for the traditional house typical for the continental part of Croatia is much higher (Cwinter / Csummer = 4.5) than for passive energy-efficient house (Cwinter / Csummer = 1.3). Additionally, year-to-year variations in radon concentrations are examined. The results showed that these variations are much higher for the passive house than for traditional houses which is quite the opposite to seasonal variations.