Assessment of indoor air quality in energy efficient residential buildings in Ireland
Citation:
Saini, Niti, Assessment of indoor air quality in energy efficient residential buildings in Ireland, Trinity College Dublin, School of Engineering, Civil Structural & Environmental Eng, 2023Download Item:
PhDthesis Master file 4(1).pdf (Thesis) 20.64Mb
Abstract:
Over the last two decades, Europe has witnessed a drive towards building energy efficiency. The EU directive on energy performance of buildings, as implemented in 2002, targeted the improvement in energy efficiency of buildings, reduction of carbon emissions and mitigation of their impact on climate change. Thereafter, further initiatives were established by the Energy Efficiency Directive (2012), which called upon the European member states to set up energy-efficiency targets to be met by 2050. The recent versions of the standard established in the Irish Building Regulations imposed a requirement on new domestic buildings to be highly insulated using a sealed external fabric to secure a building energy A-rating. Consequently, an increase in energy efficiency and airtightness has brought about a change in humidity levels internally that has led to mould formation generated by human activities, which may result in an adverse impact on user wellbeing. In addition, indoor air quality issues have been reported in the literature for a variety of high-performance buildings across the world, including offices, schools, and residential buildings.
The prediction of human behaviour, be it active or passive, is a challenge for designers. There is a lack of research on the correlation between the actual indoor air quality and the interaction between users and the installed ventilation systems as designed, which this thesis seeks to address. Inhabitants often block vents and switch off their mechanical ventilation systems or change their settings inappropriately, leading to a higher risk of health issues in these airtight dwellings.
As part of this research, the indoor air quality of 56 newly constructed energy-efficient A-rated residential dwellings in Ireland was studied to gauge the relationship between different indoor air quality parameters and the occupants? behavioural aspects. Specifically, temperature, humidity and CO2 levels were monitored for one calendar year in similar dwellings with different family profiles to establish the influence of user behaviour on these aspects of indoor air quality. For the purpose of the thesis, these three measured factors (temperature, humidity and CO2) are referred collectively as IAQ, even though factors traditionally included in IAQ are not going to be discussed such as VOCs, dust, radon, etc. as they were not measured nor considered to be a particular problem at these sites. This project seeks to assess impact of design-related factors such as house orientation, house zone, type of house, occupancy, and seasons on the different aspects of indoor air quality. Millions of data were gathered and utilised as a part of this research. Critical condition issues were analysed to determine the influence of occupant behaviour on the indoor environment through interpretation of gathered data from the installed sensors in 44 houses. Interim feedback was given to the occupants after analysing the data for six months to determine if the houses can be operated in a way to ensure adequate environmental quality throughout the seasons, whilst maintaining perceived adequate comfort levels. The impact of the advice given, and subsequent sustainability of their actions is assessed for another 6 months. Findings from this research show that many homeowners do not know how to behave in an efficient house. Results show that 40% of the houses have CO2 exceedances for more than 20% of the time and 7% of the houses have exceedances for more than 40% of the time in a winter month. Worst performing houses showed much higher CO2 levels ranging up to 5000 ppm. In winter season, 20 houses show the temperature exceedances of higher than 25 degrees, and all of them exceeded for about 1-2% of the total times. In Summers, 5 houses experienced RH exceedance to be lesser than 10%, and 13 houses reported RH exceedances to be less than 20%. 11 houses had exceedances for more than 40% of the times, and 3 houses reported RH exceedances for more than 80% while 23 houses out of 44 experienced RH exceedances for lesser than 10% of the times, and 14 houses reported RH exceedance to be more than 20%. Seven houses had exceedance for more than 50% of the times during winter.
The building type was modelled to establish its suitability in a real-life building environment using the Integrated Environmental Solutions (IESVE) software platform for modelling, including calibrating and simulating the results. Different simulations were run to resolve the issues faced by different families. The aim was to model the monitored houses with a view to predicting the consequences of family behaviour on the IAQ. It is found that different zones of the house, due to their design, suffer from poor IAQ. Recommendation of installing an extra extract in the landing area and inserting a vent grill above the door of the second bedroom in modelling showed much reduced CO2 and humidity level. The robustness of the model was tested by predicting whether it has the ability to be applied to other housing schemes. Thus, another set of 12 houses was considered for evaluating the model in which important variables that impact the temperature, relative humidity and the CO2 levels in different zones were assessed. The aim of these analyses was to substantiate the findings made under the first set of the houses, and to establish whether the impact of occupant behaviour in these houses was predictable using modelling. The findings were further synthesised to draw final recommendations for designers and occupants of A-rated homes, so that environmental quality and human behaviour trends can be integrated in enhancing the wellbeing in living spaces.
Sponsor
Grant Number
Sustainable Energy Authority of Ireland
Description:
APPROVED
Author: Saini, Niti
Advisor:
West, RogerPublisher:
Trinity College Dublin. School of Engineering. Disc of Civil Structural & Environmental EngType of material:
ThesisCollections:
Availability:
Full text availableKeywords:
Energy efficient buildings, Occupants, Indoor air qualityLicences: