AIVC - Air Infiltration and Ventilation Centre

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air change rate

Infiltration - pressurization correlations: detailed measurements on a California house.

Describes detailed study of infiltration rates measured with a tracer gas and air leakage rates obtained from fan pressurization in small, 3 - bedroom California house as part of a larger study. Finds surface pressure measurements are an essential step in process of finding a correlation between natural air infiltration and air leakage by pressurization. Measurements also show significant duct leakage and air flow between attic, living space and crawl space.

Method for calculating air exchange in domestic rooms.

Derives equations for the calculation of air-change-rate in a room where carbon dioxide is being produced at a known rate using the measured initial and final concentrations of CO2. Also derives expression for the calculation of air-change-rate with no source of CO2 but a high initial concentration

Effect of fluctuating wind pressures on natural ventilation.

Describes research project which aimed to quantify the difference between actual dynamic ventilation rates and natural ventilation rates predicted using a steady state model. 

Ventilation requirements in houses and flats. Ventilationskrav i en-och flerfamilyshus.

Reports study of the ways in which different ventilation levels affect people part 1 of the study took place in Gavle. Air change rates, the amounts of radon and its derivatives were measured. Finds that ventilation installations are often poorly adjusted giving a wide variation between flats in the levels of air change. Amounts of radon and daughters were also higher than expected, due mainly to the poor ventilation. Concludes that lowering ventilation to present recommended level of 0.5 changesper hour cannot be recommended without further investigation.

Radon and ventilation - Radon och ventilation

Describes background to natural radiation in building materials and particular aspects of radium decay which produces radon. Notes human lung capacity to absorb airborne particles and associated health risks. Illustrates diagramatically different particle sizes retained in various sections of human respiratory system. Suggests methods to avoid exposure to decay products: avoid materials with high radium content and maintain low radon concentration through sufficient ventilation. Graph shows concentration of radon in relation to air change rate.

Ventilation with open windows

Shows need for intermittent high ventilation in dwellings to remove water vapour and odours. Suggests openable windows as the simplest and most common method of ventilation control. Gives air-change-rates in two british houses using carbon dioxide andnitrous oxide as tracer gases, showing the effect of opening windows. Shows that increase in ventilation rate caused by opening windows can be tenfold and is not confined to the room with the open window. Closing of internal doors has a significant effect. Describes investigation of air flow within rooms using smoke.

Condensation risk and improved thermal performance of housing.

Considers the likely impact of alternative conservation measures on the incidence of surface and interstitial condensation on or within the elements of the building fabric. Considers specifically domestic buildings in temperate climates such as in the U.K. and Ireland. Outlines the mechanisms whereby condensation occurs and considers broadly the effect of reducing heating levels, reducing ventilation and increasing insulation.

Ventilation and air infiltration in buildings.

Briefly outlines the approach used and the results obtained by computer modelling in estimating the magnitude of natural ventilation in irish housing. Concludes that in general air-change-rates in irish housing are excessive.

The ionizing radiation in dwellings related to the building materials.

Reports measurements in seven groups of town house in Gavle, Sweden of concentrations of radon and daughter products. Gives results with the type of building materials, the ventilation systems and air-change rates measured using nitrous oxide as a tracer gas. Gives formula for the permitted limits of radionucleides in building materials. Discussed results and concludes that the concentration of radon does not differ significantly from single family to multi-family houses.

Air exchange measurements in a high-rise office building.

Reports measurements of air change rates made in the tower of an eleven-storey building using sulphur hexafluoride as a tracer gas. Inside to outside pressure differences were also monitored as a function of temperature and wind speed. Gives expression for autumn and winter air change rate as a function of windspeed. Reports finding that wind direction and stack effect had little effect on the air change rate. In this building toilet exhausts and other weather independent mechanisms were more important than natural infiltration.

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