AIVC - Air Infiltration and Ventilation Centre

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ventilation rate

A preliminary comparison of calculated building ventilation rates using six different pressure coefficient data sets.

As part of the Air Infiltration & Ventilation Centre's Numerical Database development programme, Wind Pressure Coefficient data are being collected from many published sources, much of which will contribute to the Centre's own Pressure Coefficient database. To ensure the compatibility and validity of the various data sets, a preliminary comparison has been carried out of the data in use. The work has concentrated on an analysis of the effects of Cp values, for vertical walls, on calculated wind driven infiltration and ventilation rates.

Ventilation and "building sickness" - a brief review.

As the thermal performance of buildings continues to improve, air exchange will eventually become the dominant mechanism for building heat loss. Although, therefore, an essential parameter of the energy equation, ventilation is nevertheless vital forthe dilution and removal of pollution generated within buildings. An inadequate supply of fresh air or poor air distribution will result in high levels of indoor contaminants, discomfort and a poor living environment, it could also result in more serious health related problems.

Ventilation rate measurement.

Some guidelines on indoor-air quality specify a maximum allowable exposure to CO2. In a room ventilated by a mechanical extract system a control program on the CO2 concentration may, by anappropriate sampling strategy, supply information about the exhausted flowrate. This paper briefly outlines a simple analytical model for estimating the exhausted flowrate by measuring the CO2 concentration and keeping a record of the occupancy of the room.

Sensor for continuous ventilating rate measurement in livestock buildings.

A new turbinemeter is developed to be used as a ventilating rate sensor in livestock buildings. Starting from a previous sensor, which we introduced in 1983, several improvements were done tobecome a low cost air flow rate sensor with an acceptable accuracy of 60 m3/h in a range from 200 to 5000 m3/h and this for pressure differences from 0 to 120 Pa. This sensor can beintegrated in the climate control equipment of livestock buildings to improve process control.

Prediction of the performance of various strategies of subfloor ventilation as remedial action for radon problems.

In order to reduce the convective flow which is the principal responsible for the high indoor 222Rn concentrations, several mitigation technics have been developed and used in many countries. Since they don't always respond as expected, there is a need of instruments helping in their design and their evaluation. This paper suggests the use of a numerical code, based on the finite difference method, for the evaluation of 222Rn mitigation strategies in dwellings, It is supposed that 222Rn transport from soil into a dwelling occurs mainly by pressure-driven air-flow.

Measurements of sub floor ventilation rates - comparison with BREVENT predictions.

The performance of ventilation provision in subfloor cavities is relevant to the fields of energy efficiency, condensation risk, and air quality. Thorough programs of site measurements of ventilation rates by means of tracer gas tests are in general protracted and expensive, and it is quite clear that would be highly desirable to be able to predict ventilation rates given details of building design, ventilation provision, and d.egree of exposure.

Effect of wind pressure fluctuations on air movements inside buildings.

An appropriate way to identify the most efficient ventilation systems and improve their design is to use design codes for ventilation rates. These rates are strongly influenced by spatial and temporal fluctuations in wind pressure on the facade and roof. The influence of the effects of wind on ventilation was studied using a model which includes air compressibility, together with the pressure field measured on a model in a boundary layer wind tunnel. The simulation results obtained are analyzed using a design code.

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