The purpose of this article is the assessment of energy efficiency and indoor air quality for a single-family house located in Cluj-Napoca County, Romania. The studied house is meant to be an energy-efficient building with thermal insulation, low U-value windows, and a high efficiency boiler. Increasing the energy efficiency of the house leads to lower indoor air quality, due to lack of natural ventilation. As the experimental campaign regarding indoor air quality revealed, there is a need to find a balance between energy consumption and the quality of the indoor air. To achieve superior indoor air quality, the proposed mitigation systems (decentralized mechanical ventilation with heat recovery combined with a minimally invasive active sub-slab depressurization) have been installed to reduce the high radon level in the dwelling, achieving an energy reduction loss of up to 86%, compared to the traditional natural ventilation of the house. The sub-slab depressurization system was installed in the room with the highest radon level, while the local ventilation system with heat recovery has been installed in the exterior walls of the house. The results have shown significant improvement in the level of radon decreasing the average concentration from 425 to 70 Bq/m3, respectively the carbon dioxide average of the measurements being around 760 ppm. The thermal comfort improves significantly also, by stabilizing the indoor temperature at 21 °C, without any important fluctuations. The installation of this system has led to higher indoor air quality, with low energy costs and significant energy savings compared to conventional ventilation (by opening windows).

This article presents the results of implementing a series of methods to mitigate the increased level of radon in multiple existing homes. The subject of this study is represented by techniques and systems to be implemented in pilot houses. From the 1000 house 100 houses from Cluj, Iași, Sibiu, Timiș and Bucharest were selected for monitoring purposes. From these, only 10 were chosen for mitigation. The remediation techniques applied to these pilot houses were active / passive depressurization, local ventilation with heat recovery, centralized ventilation system with heat recovery and installation of a membrane resistant to radon dispersion. In this article one house from Timisoara, and another one from Cluj, were deeply described. The mitigation of the radon level was up to 90% compared to the level measured a year ago.

This article exposes the results of radon mitigation in existing homes using decentralized ventilation equipment with heat recovery. The experimental measurement has been conducted in a large study about radon mitigation from existing homes in Romania. Various methods were treated separately to clearly expose the advantages and disadvantages for each method applied. This article focusses on the use of decentralized mechanical ventilation equipment with heat recovery. The analyzed dwelling is located in Cluj County, a radon prone area located in the west part of Romania. The preliminary measurements shown a high radon level inside the analyzed house. To prevent the high radon accumulation in the analyzed dwelling, a decentralized ventilation equipment was installed. The mean radon level inside the house decreases from 510 Bq/m3 (value recorded one year before mitigation), to approximately 361 Bq/m3 after the mitigation methods were applied, showing an reduction efficiency of approximately 30%.