Certified passive house
: An effective control of radon in domestic construction

  • Barry McCarron

Student thesis: Doctoral ThesisDoctor of Philosophy


The international Certified Passive House Standard delivers high thermal comfort based on the principles of excellent building fabric and balanced mechanical heat recovery ventilation. Considering that the typical person in developed countries (such as Ireland and the United Kingdom) spends 90% of their time indoors, there are surprisingly few academic studies on air quality in the home. Indoor air quality and the prevalence of overheating are attracting an increasing amount of research attention across Europe, but post occupancy monitoring of indoor radon concentrations is severely underrepresented, especially in Ireland and the UK.

Radon is a naturally occurring radioactive gas and known carcinogen that presents a potential risk to occupier health. This PhD research investigates measured radon levels in certified Passive House buildings in Ireland and the UK and presents the findings.

The research has found that 97 monitored Certified Passive House Standard buildings exhibit 60% lower indoor radon concentrations at 36 Bq/m3 than the national average of 77 Bq/m3 and reference levels (Target level 100 Bq/m3 and Action Level 200 Bq/m3). A series of comparison case studies located in high risk geogenic radon areas have demonstrated a significant contrast with comparison homes reinforcing the main findings.

The second major finding found a uniform distribution of radon levels between upstairs and downstairs in the Certified Passive House sample (6%) when compared against standard buildings with natural ventilation (33%-35%). The evidence from this study suggests a 18% reduction in indoor radon concentrations between timber frame construction and masonry construction. Then finally, initial evidence suggests that the EnerPhit standard (18% reduction) will mitigate against elevated radon levels in buildings being retrofitted.

This is an issue currently pertinent to the Construction Industry. The growth of energy-efficient standards (such as Passive House) and common principles (such as increased airtightness levels and mechanical ventilation systems) have accelerated the need for research data on indoor radon concentrations. This research bridges the knowledge gap between the fields of indoor air quality (specifically radon), health, sustainability, and the built environment. The study outlines the implications for policy and practice including practical recommendations.
Date of AwardJul 2021
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsSouth Western Regional College
SupervisorXianhai Meng (Supervisor) & Michael McGarry (Supervisor)


  • Radon
  • passive house
  • near zero energy buildings (nZEB)
  • indoor air quality
  • low energy buildings

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