Describes experimental studies of the natural ventilation of four similar houses with different ventilating systems. Describes houses and gives experimental procedure and results of measurements of air-change-rates using hydrogen as a tracer gas.Shows variation in air-change-rates are due mainly to changes in wind speed and that wind direction and temperature difference are secondary factors. Estimates rate of heat loss as a functionof wind speed. Discusses relationship between measured pressure differences and wind speed and direction.
Explains method for calculating time dependences and average values of gas and particle concentrations in ventilated rooms, which permits determination of air pollution propagation in a room by means of given target functions. Applies method forvarious ventilation rates. Provides calculated example of determination of gas concentration occurring in a room with a leaky gas container. Illustrates representative time functionfor different pollutants.
Describes investigation of air infiltration in a house using chlorothene as a tracer gas. Gives table of the data collected. Reports the unexpected result that infiltration rates could bereduced by increasing inside relative humidity. Suggests this is due to changes in hygroscopic building materials, especially wood. Concludes that increasing relative humidity from 20 to 40%could save from 5 to 15% on fuel costs. This analysis does not take into account the energy used to evaporate humidification water.
Describes a simple pressure method for measuring the air tightness of small buildings. It measures the leakage rate from all apertures in the external envelope simultaneously, from which total leakage area of openings could be inferred. Site measurements have shown that obvious sources of leakage like doors and windows account for only the minor part of total leakage area in the average dwelling. Results from 25 dwellings show no trend of leakage area per unit of gross floor area.
A supply of fresh air is necessary in any dwelling to ensure a comfortable, safe and hygienic environment, but the heat loss to this air, during the heating season, may represent a substantial proportion of the total heat loss. This points to the need forgreater control of domestic ventilation, either by using a mechanical system or by better design for natural ventilation. This paper touches upon both of these possibilities. Gives simple method for assessing approximately the possible reduction in heat loss achieved by the use of a mechanical ventilation system.
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.
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
Describes research project which aimed to quantify the difference between actual dynamic ventilation rates and natural ventilation rates predicted using a steady state model.
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.
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.
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