Analysis: new research evaluating retrofit homes has found indoor air quality and ventilation were not always within acceptable limits
By Asit Kumar Mishra and Marie Coggins, University of Galway
The Climate Action Plan emphasises retrofitting buildings to reduce their energy use and carbon emissions. As residences account for 25% of national energy use and 29% of carbon emissions, the Government has committed to retrofitting 500,000 homes to the cost optimum level of a building energy rating (BER) of B2. The cost optimal level is the energy performance level which results in the lowest cost during the estimated life of the home, including the upfront investment and the annual energy bills. More than 80% of Irish homes currently have a BER worse than B2.
Along with energy use, retrofits also affect home indoor environments. We spend about two-thirds of our lives inside our homes and this is likely to increase. The indoor environment at home plays a significant role in our health and wellbeing. The European Union's Energy Performance of Buildings Directive requires that member states' building energy policies consider occupant health and comfort, while improving energy efficiency.
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From RTÉ Archives, Paul Cunningham reports for RTÉ News on the introduction of a Building Energy Rating system in 2008
In a recently published study, researchers at University of Galway evaluated the indoor air quality of 14 deep energy retrofitted Irish homes to a BER of A, located in urban, semi-urban, and rural locations. The goal was to understand how the deep retrofits affected occupants' satisfaction and the indoor thermal environment and air quality. The homes had participated in SEAI's Deep Energy retrofit pilot program between 2018 and 2020.
Home were monitored at least 12 months post retrofit, for multiple indoor air quality parameters, including temperature, and humidity, fine particulate (PM2.5) and concentrations of formaldehyde and carbon dioxide. All measurements were made in the main bedrooms and the living rooms. Deep energy efficient retrofits to a BER of A or Nearly Zero Energy Buildings standards increase not only the thermal insulation but also the air-tightness of the dwelling. It is critical to ensure that these airtight dwellings are well-ventilated, resulting in homes that are energy efficient and healthy to live in.
The temperature and humidity in most homes monitored were within design comfort limits. Feedback from occupants also suggested that the home thermal environment was satisfactory. However, measurements related to indoor air quality and ventilation were not always within acceptable limits. Kitchen and bathrooms were under ventilated and some ventilation systems did not function at all.
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From RTÉ Radio 1's Brendan O'Connor Show, quantity surveyor, Patricia Power on what to do - and not do - when retrofitting your house
We spend a significant proportion of our time in bedrooms, eight to nine hours a day on average, and recorded bedroom carbon dioxide levels were over 800 ppm 70% of the time, which may indicate poor bedroom ventilation. Sleep quality plays a significant role in our health, wellbeing and performance and poor bedroom indoor air quality and low ventilation rates can disturb sleep.
Bedroom use patterns are also changing and more time is spent inside bedrooms than living rooms. Occupants of at least one home were also working from their bedroom. As working from home trends increase, the changing use of bedrooms and improving bedroom ventilation needs to be considered in future retrofit projects.
The living room PM2.5 concentrations were affected by activities like burning candles or incense, smoking, and cooking. Highest PM2.5 concentrations were recorded in living rooms but PM2.5 values on average were higher in bedrooms. Unfortunately in many homes, people rarely used the cooker hoods when cooking - even though the cooker hoods met regulations - which led to increased levels of PM2.5 intermittently.
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From RTÉ Radio 1's Today With Claire Byrne, retrofitting Q&A with Oliver Kinnane and Shane Colcough from UCD's School of Architecture Planning and Environmental Policy
Residents generally found the indoor air quality to be agreeable, though satisfaction with thermal environment can often mask issues with this. Humans are good sensors for thermal conditions (particularly temperature), but not too good at discerning indoor air quality. The odour threshold of a carcinogenic pollutant like formaldehyde can be five to 50 times the levels that are of concern from a health point of view. Low cost indoor air quality monitors could help occupants monitor the level of some pollutants such as carbon dioxide, in their homes and can be integrated in the home management system.
Mechanical ventilation is a key measure when deeply retrofitting buildings to a BER of A in order to ensure good air quality. This is a relatively new concept for Irish residences. These systems need to be designed and installed correctly and validated for their performance by independent third party professionals such as NSAI.
Periodic checks and maintenance is required to ensure home ventilation is operating in an efficient and effective manner
Homeowners should also be provided with sufficient information about the ventilation system so that it can be operated in an efficient and effective manner. A requirement was introduced in 2019 in Ireland for third party validation of ventilation systems in new dwellings and dwellings undergoing major renovation where mechanical ventilation has been installed. This is a welcome move, which has been followed by other EU member states.
Periodic checks and maintenance is required to ensure home ventilation is operating in an efficient and effective manner. One of the immediate impacts of our work was that some home owners got in touch with the installers when made aware of ventilation system performance issues in their homes. This led to a quick check and maintenance of the system, resulting in improved home ventilation. Since the study has been published, the Department of Housing, Local Government & Heritage have developed free guidance on importance of ventilation for IAQ at home which can be accessed here.
The study by researchers at the University of Galway was part of the Sustainable Energy Authority of Ireland-funded Arden project and funded under the SEAI Research, Development & Demonstration Funding Programme 2018, Grant number 18/RDD/204
Dr. Asit Kumar Mishra is a Postdoctoral researcher in the Sustainable & Resilient Structures Group of the College of Science and Engineering at University of Galway. Dr. Marie Coggins is a Senior Lecturer in Exposure Science at the School of Natural Sciences and a member of the Centre for One Health at the Ryan Institute, University of Galway.
The views expressed here are those of the author and do not represent or reflect the views of RTÉ
