In response to the challenges of climate change, a global shift in building standards and practices is currently underway. In the UK and Ireland, this has been evidenced through substantial improvements of thermal performance and airtightness in new-build and retrofitted dwellings. Whilst improvements in fabric performance should lead to health benefits (particularly for households in fuel poverty), there is now growing concern that the practice of increasing airtightness and limiting ventilation to reduce heat loss may result in indoor air quality problems. These concerns have been exacerbated by reduced space standards, the use of new untested building materials and products, the increasing reliance on mechanical ventilation in new-build housing and the growing housing shortage in the UK. However, while awareness of the risks of increasing airtightness on indoor air quality in housing is growing, there remains a significant lack of evidence of the potential health implications. Research of this nature requires a fundamental understanding of the complex interplay between the climate, building design, occupant behaviour, air quality, toxicology and health.