Defining demand: The suitability of sensor-based demand-controlled ventilation within deep energy retrofit dwellings

This paper reviews a Sensor-Based Demand-Controlled Ventilation (SBDCV) system which seeks to provide fresh air for breathing and to dilute and exhaust pollutants and odours. Previous studies have demonstrated that the constant pressure system increases ventilation extract and inflow based on relative humidity levels and/or presence detection and works on the assumption that the level of ventilation provided is sufficient to control the concentration of all indoor air pollutants, including those that are not occupant generated. This paper presents the results obtained from monitoring the indoor air quality of eight dwellings that had undergone a fabric-first deep energy retrofit and had an SBDCV system installed. It is demonstrated that while the large-scale deep energy retrofit of dwellings will result in consistent temperatures and an appropriate range of humidities, the SBDCV system is insufficient to ensure the removal of all occupancy and non-occupancy related pollutants and an alternative approach that addresses this shortcoming is required. The findings demonstrate that the use of SBDCV in deep energy retrofit could have significant health and wellbeing impacts for occupants. The findings have implications for the policy framework, particularly in the context of large-scale retrofit targets, grant aid supports and the requirement for healthy homes.