https://doi.org/10.1140/epjs/s11734-026-02348-1
Regular Article
Decentralised ventilation with heat recovery for indoor radon mitigation: insights from long-term monitoring
1
Helmholtz Centre for Environmental Research—UFZ, Leipzig, Germany
2
Saxon State Office for Environment, Agriculture and Geology, Dresden, Germany
3
SARAD GmbH, Dresden, Germany
4
inVENTer GmbH, Löberschütz, Germany
a
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Received:
24
August
2025
Accepted:
24
April
2026
Published online:
20
May
2026
Abstract
Indoor radon-222 is a primary contributor to radiation exposure in homes and workplaces and poses a significant lung cancer risk. In Germany, the reference value for the annual mean indoor radon activity concentration is 300 Bq/m3, in line with international recommendations. This long-term proof-of-concept study evaluated the effectiveness of a decentralised ventilation system with heat recovery, operated by real-time radon measurements as the control parameter, in a ground-floor flat located in a radon-prone area of the Ore Mountains, Germany. Between May 2020 and January 2025, 73 ventilation experiments were conducted. For analysis, all ventilation experiments were considered collectively and compared to periods without ventilation (initial state). The results show that decentralised ventilation substantially reduced indoor radon activity concentrations across all rooms. Seasonal variability was confirmed, with higher levels in winter and lower levels in summer, and interannual differences were documented over nearly 5 years. While the living room consistently approached or fell below the German reference value of 300 Bq/m3 during ventilation phases, other rooms remained above this threshold, underlining both the effectiveness and the limitations of the system. These findings highlight the need for customised and site-specific mitigation strategies that integrate environmental and building-specific factors into radon risk assessment and mitigation planning. Overall, decentralised ventilation with demand-driven, radon-based control represents a promising approach for radon mitigation in existing buildings, particularly in high-risk areas.
© The Author(s) 2026
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