Two models were applied to predict particle deposition in ducts, one theoretical, the other based on experiments. These models are described and a comparison of their predictions is compared to experimental results.
The study has monitored two office buildings during 3 years changing position of dampers in order to control the air change in the buildings on periods of 3 months. CO2 levels, absenteism rate and rhinovirus in air samples are commented.
Visual inspection is a subjective method but yet necessary to control duct cleanliness. In order to improve its reliability, a visual scale has been realised and results from a panel of 10 inspectors have been compared to measurements.
A new version of 'classification for indoor climate, construction and building material' has been published in 2001 in Finland, giving recommendation on ventilation systems and their cleanliness. Procedures to test values and check criteria are given.
CFD calculations were performed in a ventilated room of 5.7 m2, with an air supply near the floor and an air exhaust near the ceiling on the opposite wall. Air flow rate and inlet temperature are 14.3 l/s and 22C. Calculation results show for example that a standing or seated occupant inhales air coming from the aera close to the floor, which flows upwards due to metabolic heating. A new index (IECI) was used to characterize the effectiveness of contaminant inhalation. The higher values of IECI in the room indicate the zones which the inhaled air comes from.
The study presents the influence of three different air diffusion systems and furniture layout on comfort (PMV, PPD) and indoor air quality (ventilation efficiency). Results of CFD calculations have been validated using experimental results for one case on a test rig. Charts are given to help dimensioning.
Measurements were carried out to assess the transfer of outdoor air pollution (CO, SO2, NO, NO2, O3, BTEX, TVOC, fine particles, smoke index) into an unoccupied and empty dwelling in Paris, in winter and summer. The controlled air exchange rates were 0.6 and 0.9 volume/h. Some pollutants have a reduced concentration indoors (NO, SO2, O3, particles, smoke index) as others are transferred (like CO). Some results were also obtained with sorbing materials inside the dwelling, which reduce indoor concentrations.
The aim of the BASE study was to collect air quality data for office buildings in the USA, using air flow rates measurements or tracer gas (CO2) methods. Results for 100 buildings are summarized : 11 % of buildings have outside air ventilation rates below ASHRAE recommendations. The accuracy and the limitations of the measuring methods are also analyzed. CO2 tracer gas method best represents the ventilation rate.
Field tests and a model allowed to study contaminant concentrations in a single family home in California operating with natural ventilation or with one of six mechanical ventilation systems (cyclic or continuous, multi-point or single-point exhaust). Continuous ventilation appears to be better for contaminant levels control.
This study is an analysis of the advantages of two ventilation systems (exhaust mechanical ventilation, balanced mechanical ventilation with heat recovery) using the Negative Index approach, which is affected by life cycle cost and environmental impact. The balanced system appears to be a better choice (less environmental impact, better indoor air quality) even if its life cycle cost is higher.
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