IAQ

During the project QUAD-BBC, several ventilation systems have been studied in residential (individual house and collective dwellings) and non-residential (school, offices) and assessed by the evaluation of an IAQ multi-criteria.
These calculations have shown some typical evolution of pollutants in very tight low consumption buildings and can alert on some possible effects.

Building sealing may affect the total air change by decreasing the leakages and question the ability for ventilation systems to reach their goal of providing an acceptable indoor air quality. Improving energy performance must not impair indoor air quality.

The paper summarizes the activites undertaken by AppliedSensor within the European Clear-up project with respect to new developments in volatile organic compound sensing for demand controlled ventilation. State-of-the-art is to use non-dispersive infrared sensor technology for indoor carbon dioxide detection. Carbon dioxide so far serves as indicator for bad indoor air quality and required ventilation rates.

As part of a field measurement project of unvented gas fireplaces in 30 homes, portable carbon monoxide sensors were located in several places in each home. This was done to assess the degree to which combustion by-products became distributed throughout the home. The sensors indicated that carbon monoxide levels began rising throughout the home almost immediately, at or near the one-minute sampling interval. The results show that, on average, the reading in the middle of the fireplace room was about 95% of the reading at the mantel.

Stratified ventilation systems use a fundamentally different approach to supply heated or cooled air through a building than the ‘fully mixed and dilution’ ventilation systems found in the majority of non-residential buildings. Stratified air distribution creates a non-uniform environment in terms of temperature and pollutant distribution, and acceptable conditions in the occupied zone. Previous research has shown that this type of system works well for regions where buildings require year-round cooling.

To clarify the indoor climate in Japanese college classrooms, an air-conditioned, mechanically ventilated classroom of a university was surveyed. Temperatures, humidity and carbon dioxide (CO2) concentration in winter and summer were measured before, during and after lessons. The airtightness of the room and the airflow rate of the ventilation system were also measured. In winter, at an outdoor air temperature around 0 ºC and with the thermostat temperature of the air conditioners set to 30 ºC, the vertical difference in room air temperature exceeded 10 ºC.

For residential forced air heating and cooling systems conventional thinking is that air supply registers should be located under exterior windows. There were good reasons for this in the past (primarily to counteract the cold downdraught from the window) but new construction standards (well-insulated walls, better glazing and air tight wall/window interface) mean that there is now less downdraught. Positioning the supply air register away from a window could have a large impact for new construction as duct lengths could be shortened (saving materials and construction time).

Increasing demand for energy efficiency places new requirements on energy use in historic buildings. Efficient energy use is essential if a historic building is to be used and preserved, especially buildings with conventional uses such as residential buildings and offices. This paper presents results which combine energy auditing with building energy simulation and an indoor environment survey among the occupants of the building. Both when comparing simulations with measurements as well as with survey results good agreement was found.

Distributed demand control ventilation (DDCV) has shown potential for improving both indoor air quality (IAQ) and energy consumption over conventional ventilation systems. However, ventilation strategies based on measurements of CO2 concentrations suffer from several shortcomings due to issues related to accuracy and drift of off-the-shelf CO2 sensors as well as the highly non-uniform distribution of CO2 in typical office environments.