The suitability of demand-controlled sensor based ventilation systems in retrofit dwellings - a longitudinal study

A fabric-first approach to dwelling retrofit results in increased airtightness, therefore there is an obligation to ensure that the upgrades do not lead to poor indoor air quality (IAQ) resulting from inadequate ventilation. The sensor-based demand-controlled ventilation (SBDCV) under review seeks to provide fresh air for breathing and to dilute and exhaust pollutants and odours. This system modulates the ventilation rate over time based on relative humidity levels and/or presence detection and considers that the level of ventilation provided is sufficient to control the concentration of all other indoor air pollutants, including those that are not a result of human occupancy. This research takes the form of a longitudinal study that follows a structured approach to monitor the levels of relative humidity, radon, and volatile organic compounds within participating dwellings (n=7) so that the relationship between the variables can be explored. This paper demonstrates that SBDCV systems are insufficient to ensure the removal of non-occupancy related pollutants. This could have significant health and wellbeing impacts for occupants. The findings of the paper have implications for the policy framework.