AIVC - Air Infiltration and Ventilation Centre

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air change rate

Atmospheric turbulence influence on natural ventilation air change rates.

In order to estimate air change rates (ACH) on Natural Ventilation (NV) processes a number of factors should be known as general and openings dimensions, pressure distribution over the facades, internal heat sources (or sinks) and head losses. The atmospheric boundary layer (ABL) characteristics change with the terrain roughness and affect the pressure distribution. Construction features determine infiltration rates, flow regimes through openings and its head losses so affecting the internal airflow.

Comparison of indoor air quality between air-conditioned building and naturally ventilated building during heating season.

Field measurements were made during the heating season to compare IAQ between an air– conditioned building (Building A) and a naturally ventilated building (Building B) situated in the centre of Pyongyang and similar in architectural design, number of occ

Experimental study of mixing in a closed room by doorway exchange flows.

We present a series of analogue laboratory experiments of the transient exchange flow between a room filled with warm air and a cold exterior following the opening of a doorway. Our experiments suggest that the time-scale for mixing the fluid in the room below the top of the doorway is independent of the door height. We then describe the steady-state two-layer stratification that is established when, in addition to the exchange flow, a localised heat source provides heat at the base of the room.

A new technique for measuring air change rates in a test house using video imaging.

Video camera calibrations and field tests for air change rates in a test house were performed to develop a new method of measuring air change rates using a video imaging technique. From the camera calibrations, it was found that good correlation was achieved between image signals and luminous reflectance of achromatic color chips by appropriately adjusting the pedestal level of the video camera so that the image signals were made equal to zero for the black level of the picture.

Evaluation of the COMIS model by comparing simulation and measurement of airflow and pollutant concentration.

This paper describes the measured and calculated results of airflow rates and pollutant concentration profiles in an airtight test house, the aim being to evaluate the calculation model COMIS for multizone air infiltration and pollutant transport. Firstly, the leakage areas of internal doors, exterior walls and windows were measured by the fan pressurization method. Secondly, two measurements were carried out, assuming that the test house consisted of ten zones.

Parameter estimation of unknown air exchange rates and effective mixing volumes from tracer gas measurement for complex multi-zone indoor air models.

The steepest descent and simulated annealing optimization techniques are used to simultaneously estimate the effective mixing volumes and air exchange rates of a large partition less building exhibiting heterogeneous spatial air flow conditions. The optimization is conducted using varying quantities and qualities of simulated tracer gas measurements. A simulated three-compartment system is numerically investigated to assess the performance of the parameter estimation methods.

Theoretical and Field Study of Air Change in Industrial Buildings

The air leakages can have a large impact on heating needs and thermal comfort in industrial buildings. This is sometimes poorly taken into account, both due to the lack of theoretical approach and knowledge of air tightness.