airflow

Purpose of the work

Quantification and location of moisture penetration through leak-dependent creeping flows from the room into insulated, lightweight wall structures as a function of design, pressure differential, and leak position.

Method of approach

Pressure-dependent, high-precision through-flow measurement in a facade test stand and determination of the amount and distribution of condensate in a double climate chamber performed on lightweight wall sections with different cavity wall insulation and leak positioning.

The estimation of low-rise, residential building infiltration rates using envelope airtightness values from whole building fan pressurization tests has been the subject of much interest and research for several decades, constituting a major topic of discussion during the early years of the AIVC. A number of empirical and model-based methods were developed, with their predictive accuracy evaluated in field studies around the world.

A common room-heating technique involves the use of a wall-mounted radiator without forced convection. The cold surrounding air passes adjacent to the warm surfaces of the radiator where it absorbs heat and gains momentum to rise along the wall surface and finally circulate in the entire room. Understanding the properties of heated airflows is important for several purposes. To understand the flow process it is important to identify where the transition from laminar to turbulent flow occurs and to quantify the turbulent fluctuations.

Door operation and the subsequent passage of occupants through the doorway can cause containment failures in hospital isolation rooms. Typically hinged doors are used between the isolation room and anteroom/corridor in healthcare facilities. However, sliding doors can reduce door induced airflows through the doorway and hence effectively reduce the contaminant outflow during the door operation.

For the coming energy-efficient buildings, the guarantee of energy performance becomes a major challenge. It is therefore crucial to implement accurate and reliable measurements, in order to ensure this performance. The in-force French EP-regulation RT2012 already imposes compulsory justification of envelope airtightness. Moreover, the Effinergie+ label requires ventilation systems control and ductwork airleakage performance. These requirements, ventilation controls for IAQ concern and regulatory compulsory controls of buildings need reliable diagnostic protocols.

The moving human (MH) influences the airflow and contaminant distribution, this paper use the commerce software FLUENT6.2 to simulate the influences of the MH to the airflow and TVOCs distribution in both mixing ventilation and placement ventilation. In a three-dimension ventilation room, a pollutant source (TVOCs) was located on the floor and a flesh in a certain zone moving was assumed,  and the unsteady, k-ξ turbulent model be used, According to the simulation results, we studied the influence of MH in the indoor air quality in both mixing ventilation and displacement ventilation.

A model tunnel (approximately ten hydraulic diameters) with different designs of the tunnel mouth has been placed in a wind tunnel and has been subjected to the effects of external wind by varying the wind direction at the mouth of the tunnel. In the experimental oriented study pressures have been measured and the airflow has been made visible with smoke and by the sand erosion method (semolina). The relation between the flow ratio and the direction of the wind has been explored.

This paper discusses the accuracy of commercially available flow hoods for residential applications. Results of laboratory and field tests indicate these hoods can be inadequate to measure airflows in residential systems, and there can be large measurement discrepancies between different flow hoods. The errors are due to poor calibrations, sensitivity of the hoods to grille airflow non-uniformities, and flow changes from added flow resistance.

Tracer gas techniques have been the most appropriate experimental method of determining airflows and ventilation rates in houses. However, current trends to reduce greenhouse gas effects have prompted the need for alternative techniques, such as passive sampling. In this research passive sampling techniques have been used to demonstrate the potential to fulfil these requirements by using solutions of volatile organic compounds (VOCs) and solid phase microextraction (SPME) fibres.

There is a growing desire to reduce peak temperatures within non-domestic buildings by accessing the thermal mass of separating floors. These floors are typically formed of concrete and can store reasonable amounts of heat. Unfortunately, they are usually thermally isolated from the room below by a suspended ceiling. Therefore, some architects try to access the concrete by leaving a perimeter gap in the suspended ceiling in each room to allow airflow across the underside of the separating floor. For visual and acoustic reasons, there is the desire to make this gap as small as possible.