The present study aimed at investigating the effects of ventilation strategies on indoor air quality (IAQ) in schools. Measurements of thermal environment and IAQ were performed over 5 school days in 45 primary school classrooms in Gothenburg, Sweden, grouped into three categories according to their ventilation system: category A) natural or exhaust ventilation, or automated window opening; category B) balanced mechanical ventilationsystems with constant air volume (CAV) and category C) balanced mechanical ventilation systems with variable air volume (VAV). The classrooms performed equally well with respect to temperature and relative humidity regardless of the ventilation system. The concentrations of the air pollutants in all classrooms were generally below the respective guideline values. The concentrations of CO2, formaldehyde, PM10, and PM2.5 were lower in the B and C category classrooms with higher ventilation rates than in the A category classrooms. Indoor Air Pollution Index integrating concentrations of multiple pollutants was significantly higher the A category classrooms, reflecting poorer IAQ. Majority of the classrooms had lower ventilation rates than the Swedish ventilation requirements. The periodically reduced ventilation rates in the classrooms with VAV systems did not lead to substantial increase in the measured indoor pollutant concentrations.
Buildings are responsible for a substantial portion of the global energy consumption. Most of the multifamily residential buildings built in the 20th century in Central and Eastern Europe do not satisfy the current requirements on energy efficiency. Nationwide measures taken to improve the energy efficiency of these buildings rarely consider their impact on the indoor air quality (IAQ). The objective of the present study was to evaluate the impact of simple energy renovation on IAQ, air exchange rates (AER) and occupant satisfaction in Slovak residential buildings. Three pairs of identical naturally ventilated multifamily residential buildings were examined. One building in each pair was newly renovated, the other was in its original condition. Temperature, relative humidity (RH) and the concentration of carbon dioxide (CO2) were measured in 94 apartments (57%) during one week in the winter. A questionnaire related to perceived air quality, sick building syndrome symptoms and airing habits was filled by the occupants. In a companion experiment, the IAQ was investigated in 20 apartments (50%) of a single residential building before and after its renovation. In this experiment, concentrations of nitrogen dioxide (NO2), formaldehyde and total and individual volatile organic compounds (VOC) were also measured. CO2 concentrations were significantly higher and AERs were lower in the renovated buildings. Formaldehyde concentrations increased after renovation and were positively correlated with CO2 and RH. Energy renovation was associated with lower occupant satisfaction with IAQ. Energy retrofitting efforts should be complemented with improved ventilation in order to avoid adverse effects on IAQ.
Air pollutant exposure in workplace environments has been associated with health and cognitive outcomes ofworkers. While green building certification programs have been instrumental in promoting indoor air quality(IAQ), the present literature indicates inconsistent evidence. Recent emergence and proliferation of WELL certification program that prioritizes human health has evoked new questions about its effectiveness in relation toIAQ. To investigate the effectiveness of the WELL certification, we have quantitatively compared IAQ resultsbefore and after relocation to two WELL-certified office buildings using the same cohort of occupants.
Physicalmeasures included integrated samples of TVOC, individual VOC, formaldehyde and acetaldehyde, NO2, SO2, O3and longitudinal records of CO2 and size-resolved particles. Complementary survey responses about satisfactionwith IAQ and thermal comfort were collected from ~250 employees. For the majority of air pollutants, there wasno significant concentration difference between non-WELL and WELL buildings, but not always. The WELL-certified buildings had substantially higher levels of TVOC and individual VOC associated with paints, especiallyshortly after the relocation. However, there was statistically significant improvement in IAQ satisfactionafter relocation into WELL buildings regardless of the air pollution levels, possibly confounded by thermalenvironment, awareness of the WELL certification or other non-measurable factors.
Data from a nationwide survey on the status of the Swedish residential building stock and indoor air quality wasplaced in the public domain by the National Board of Housing, Building and Planning of Sweden. The currentresearch investigates the indoor humidity conditions in Swedish residential buildings, single-family houses andapartments, assessing the measurements from the extensive BETSI-survey against adjusted relative humiditylevels based on existing norms and Standards. The aim of this study is to investigate associations and correlationsbetween relative humidity levels and multiple building and system characteristics, occupancy patterns and behaviors and health symptoms-complaints. The analysis uses 13 categorical and 9 continuous variables-parameters of the examined dwellings.Analysis shows that low indoor relative humidity is a realistic issue in Swedish dwellings during the heatingseason. The issue is more prevalent in apartments than single-family houses. In addition, low indoor relativehumidity seems to be more extensive in dwellings with higher indoor temperature, smaller volume, higherventilation rate and frequent airing practices, lower number of occupants, constructed mainly after 1985, in citysuburbs and in the northern parts of the country. The developed multinomial logistic regression model maypredict very accurately the relative humidity level of the Swedish dwellings, during heating season. This analysisoffers additional evidence to the scientific literature for possible correlation of low relative humidity with specifichealth symptoms, complaints and disturbances.
Residential indoor climate is a key factor for occupant comfort, health and wellbeing, while also affecting the buildings’ energy demand. A strong focus has been traditionally placed on low winter indoor temperatures in dwellings due to their considerable health impacts. However, there is a trend towards high and stable indoor temperatures, which also have significant implications. This paper investigates the drivers of winter indoor temperatures by analysing the following three metrics of measured temperatures in a sample of 1039 Swedish dwellings: a) level, through the sample dwellings’ standardised indoor temperatures at 5oC outdoor temperature, b) daily variation, through the standard deviation of the indoor temperature and c) shape, using daily indoor temperature profiles derived from cluster analysis. The study explores the association of these metrics to building-, dwelling- and occupant-related parameters.
The analysis shows that 80% of the standardised indoor temperatures were above 21oC, with one third of the latter being above 23oC, while 82% of dwellings had constant temperatures throughout the day. High winter indoor temperatures were more evident in middle-placed apartments in multi-family buildings connected to district heating and in better insulated single-family houses. High temperatures were also associated with experiencing draft from windows, too warm conditions in winter and difficulty to control the indoor temperature, but not with the overall thermal comfort assessment which was very positive in both the high and low temperature tails. Long-term adaptation effects, established norms and comfort expectations are discussed as important confounding factors in the development of residential indoor temperatures.