Gathering baseline data to assess household energy interventions' impact on indoor air quality, occupant health, and wellbeing: In2Air a non-randomized experiment

Background: Tackling climate change, together with improving indoor air quality (IAQ), offers a significant opportunity to improve residents’ health and wellbeing. To do this requires the evidence base on which to inform energy efficient retrofit design.

Objectives: i) to develop a protocol that could be implemented by local authorities across a range of housing typologies, and ii) to deploy this protocol to establish baseline conditions in n=30 homes ahead of energy efficient retrofitting.

Methods: Working with the local council and the community, this baseline study (In2Air) developed and deployed a protocol across 30 single-story one to two bedroom properties owned by Newcastle City Council, UK, and occupied by tenants (> 55 years).The following data were collected before homes underwent a fabric-first intervention: indoor and outdoor air quality (for ~3 weeks); energy consumption (for ~12 months); occupant behaviour and home-specific details; self-reported general health and wellbeing.

Results: The collected baseline data indicated mean PM2.5 concentrations ranged from 3 – 24 µg/m3 (excluding three homes where smoking occurred indoors). No homes had monitoring period means above the current UK (2019) outdoor annual mean limit (25 ug/m3), however 21 homes had monitoring period means above the current WHO (2021) annual mean guidance value (5 ug/m3).

Strong correlations were observed between indoor PM2.5 and indoor PM10, suggesting similar sources, whilst no to weak correlations were observed between indoor CO2 and indoor PM2.5. Moderate to good ventilation was suggested by indoor concentrations of CO2 across all the study homes. The lack of correlation between CO2 and PM highlights the need for housing professionals to add PM to their usual indoor air quality assessment suite of CO2, temperature and humidity.

Most homes had mean humidity levels within the range considered healthy (i.e. between 40-60%), with only three homes above this range. With respect to the baseline health and wellbeing scores, compared to the comparison population, data for this first timepoint indicated most participants (83%) had a physical health score below the norm which likely reflects the age (> 55 years) of the cohort. In comparison, the mental health score for most participants (74%) was at or above average. Here the physical layout of the estate with communal amenities may well be engendering a positive sense of belonging. The mean/median ICECAP score suggests a high level of capability across the cohort.

Limitations: Our study focused on changes to the building envelope across a limited number of building types and parameters and utilised fixed, low-cost sensors at indoor and outdoor monitoring locations rather than personal air quality monitors.

Conclusions and Future Work: The baseline conditions reported in this article provide the basis on which to inform and evaluate the effects of energy efficient refurbishment across this social housing stock as part of future research. The developed protocol, and the study findings, offer the potential to support and inform decision making of council retrofit teams across the UK with their ongoing decarbonisation plans.