Indoor air quality and ventilation in deep energy retrofitted Irish dwellings

Research evaluating home retrofits in Ireland has found that air quality and ventilation were not always within acceptable limits, University of Galway Senior Lecturer in Exposure Science Marie Coggins tells eolas Magazine.

Coggins was one of eight authors of the report Indoor air quality, thermal comfort, and ventilation in deep energy retrofitted Irish dwellings that monitored the air quality, thermal comfort, and ventilation in homes that had participated in the SEAI’s deep retrofit pilot programme between 2018 and 2020. The research, funded by SEAI, found there to be only four bedrooms surveyed that had carbon dioxide concentrations within the optimal Category I limits for CO2 in bedrooms, from EN16798, the European standard governing thermal comfort.

Homes involved were up to 52 years old, and at the time of the studies, the homes were 12 months to three years post-retrofit. There was a mixture of detached and semi-detached homes with floor areas ranging from 50m2 to 300m2, all with cavity walls and non-smoking residents. There was a significant increase in the BER of the homes post-retrofit and associated with that was a significant improvement in air tightness.

The researchers examined volatile organic carbon, a term for many different chemicals that are volatile at room temperature, carbon monoxide, carbon dioxide, temperature, and relative humidity. Homeowners completed a detailed questionnaire that included questions about thermal comfort, perception of the retrofitting process, and how happy the homeowners were with the end product. Homeowners also completed a diary, noting tasks such as cooking, burning candles, and cleaning pets that can generate pollutants and that is needed to understand what was going on at any given time in order to understand spikes in the data received around pollutants in the home.

“Unfortunately, only 35 per cent of homes complied with the ventilation requirements in S.R. 54 [the standard that had regulated retrofits at the time] and if we were looking at the current requirements, only 21 per cent homes complied with ventilation requirements in the current building regulations,” Coggins says.

“Following the surveys, we prepared a newsletter for the homeowners and some of the homeowners followed up with the retrofit providers and asked to have their ventilation systems checked. In many cases the underperformance was due to lack of servicing.

“If we look at the data we found in the homes, we can see that the thermal comfort was okay, with only 30 per cent of bedroom data outside of Category 1. Up to 50 per cent of living area data was outside of Category 1, but this was primarily due to the glazing in these living rooms. Higher concentration of all air pollutants studied were detected in bedrooms, suggesting underventilation.”

PM2.5 (small solid or liquid particles suspended in air) exposure is said to be responsible for about 1,300 premature deaths annually in Ireland, but this data only relates to outdoor exposure and Coggins points out that 70 per cent of our exposure to fine particulate matter actually occurs indoors. Other chemicals, such as formaldehyde, which has been classified as a 2A carcinogen, are regularly measured. Radon is also “a significant challenge” for Ireland and is a class one carcinogen, causing one in 10 lung cancers.

“In terms of formaldehyde, we are above the recommended one-year long-term exposure limit recommended by [United States federal agency] the Agency for Toxic Substances and Disease Registry,” Coggins says. “With radon, which is particularly important with retrofit, we have indicated the homes within high radon areas and of course they are the homes most likely to exceed recommended radon levels.

“In terms of fine particulate matter, most of the time we were able to see that night-time CO2 and PM2.5 was negatively correlated, suggesting that most of the particulate was coming from occupant activity in the home. This was corroborated by what we saw in the diaries: cooking breakfast, lunch, and dinner, candle and incense burning caused high spikes of PM. There was very low reported use of cooker hoods, another issue related to ventilation.”

Despite these findings, Coggins says that the returned questionnaires showed that people were “very happy with the thermal comfort post-retrofit and were happy with the air quality in their homes”. This is partly due to a challenge with perception, she says: “Humans are incapable of sensing the concentrations of pollutants at levels that matter. We need more education to create a greater awareness of the importance of indoor air quality but there is also a role for low-cost sensors like we had during the pandemic with CO2 sensors to help us flag when ventilation is not right.”

“Retrofitting provides a real opportunity to transform the living conditions of millions and improve our health and wellbeing.”

Indoor air quality is of particular interest in Ireland, which has “fourth highest rate of asthma occurrence in the world and the third highest rate of COPD” and, as Coggins says, “many of the pollutants that we detect indoor are triggers for these conditions”.

“Retrofitting provides a real opportunity to transform the living conditions of millions and improve our health and wellbeing,” she says.

Key to this is further regulation around ventilation and further education, Coggins says, enabling the development of a true awareness of indoor air quality.

“There is no requirement to install extract ventilation in bedrooms, where we found much higher levels of indoor pollutants. We have requirements to ventilate wet rooms such as ensuites but not bedrooms. We spend eight to nine hours per day in the bedroom and it is important to have good ventilation in there. As we move towards more hybrid models of working, more people are using their bedrooms as offices, so we need to look at that. We need more compliance with the ventilation aspect of retrofit; as we make the building more airtight, the main exposure control we have is ventilation. Since this study was completed, there has been an introduction of third-party ventilation checks, which is good, but it does not include cooker hoods or ongoing maintenance of the system. Homeowners do not perceive indoor air quality as an issue and are not aware of how to deal with such issues.

“For the building sector, we have to select low chemical emitting products. We were able to correlate bedroom and living room materials to suggest that the main source of volatile chemical carbons such as formaldehyde were in the building materials. That is not new and has been seen across Europe. Other countries have reacted by introducing labelling systems, to help select low emitting volatile organic compound products, and we could introduce something similar here. The other aspect is, as we train more people to provide nearly zero energy buildings, we need to make sure that indoor air quality is part of the curriculum and that we are delivering healthier outcomes,” she concludes.