AIVC - Air Infiltration and Ventilation Centre

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air change rate

Air infiltration measurement and reduction techniques on electrically heated homes.

Reports two-year programme to evaluate the effect of air infiltration on the heating needs of 29 electrically heated homes. Air-change rates before and after retrofitting tominimize infiltration were measured by a pressure method and heat energy consumption and occupancy effects were monitored. Thirty similar homes were also tested for infiltration and retained as controls.< Describes the retrofit methods, their effect upon the induced air infiltration, the other data which are being collected, and the data analyses which are expected at the completion of the programme.

Principles of natural ventilation

Discusses the mechanisms which govern natural ventilation. These are wind speed, flow, characteristics of openings in buildings and pressures generated at building surfaces by wind and temperature difference. Gives formulae for simple cases. Outlines ways of determining natural ventilation rates. Gives brief account of the effect of turbulence and openings in one wall only.

An optical technique for measuring of ventilation rates in models.

Describes adaptation of photo-electrical optical technique to measure ventilation rates in wind tunnel models. Illustrates probe photographically and diagrammatically. It comprises essentially a light-emitting diode and a hybrid photodiode-amplifier detector. Compares technique with conventional tracer gas technique using helium and a katharometer and finds good agreement. Considers optical probe has considerable potential for measurements in small and multi-celled models where conventional techniques are not feasible.

A low-cost method for measuring air infiltration rates in a large sample of dwellings.

Presents method for collecting air infiltration data in a large sample of dwellings. The method consists of a tracer gas dilution technique using sulphur hexafluoride and employing air sample bags which are analyzed in a central laboratory. Themethod is easy to perform and inexpensive and will be used in approximately 300 dwellings on 16 sites to give air exchange rates under typical heating season conditions. Presents preliminary data on air infiltration rates in low-income housing in Portland, Maine.

Wind tunnel and on-site pressure distribution measurements on a house and its effects on infiltration

Summarizes measurements made on a flat. These include inside to outside temperature and pressure differences, infiltration rates using helium as a tracer gas, duration of opening windows and doors and weather conditions. Also describes wind tunnel measurements made on a model of the building with and without obstacles and terrain roughness.

Results of air-change-rate measurements in swiss residential buildings. Luftwechsel Messwerte von ausgewahlten Wohnbauten in der Schweiz

Reports results of studies conducted in Switzerland in small apartment buildings. Air change rates were measured in ten different apartment buildings using N2O as a tracer gas. Measurements were taken for various wind conditions andtemperature differences and with the windows partly open. Finds that ventilation rate increased by a factor of 4 when the windows on one facade were opened by only a few centimetres.

A proposed method of measuring the rate of air change in factories

Proposes a method for measuring the rate of air change in factories using ammonia as a tracer gas and measuring its rate of decay by a colorimetric method. The advantage is that extremely small quantities can be detected. The method is cheap, easy to use, reasonably accurate and unobjectionable to the occupants.

Method to determine air change rates using krypton-85 and its application to tests in stables. Die Technik der Luftwechselbestimmung mit radioaktiv Krypton-85 und ihre Anwendung auf Untersuchungen in Stallen.

Discusses the principles involved in measuring air change rates using tracers and gives the theory. Outlines the preparation of the tracer and the test procedure in stables. Finds that satisfactory results can be obtained when the concentration of krypton-85 is only one tenth of the maximum allowable. Lists the advantages of the method.

Air change rates in dwellings. Luftwechsel in Wohnungen.

Points out that increased levels of thermal insulation in dwellings make ventilation heat loss an increasingly significant proportion of total dwelling heat loss and of great significance for sizing heating installations and selecting their control equipment. Treats attempts to reduce ventilation loss by specifying greater tightness of building structures, especially windows.

Air leakage in split-level residences

Reports investigation of air change rates in two residences using helium as a tracer gas. Gives results of measured air change rates, wind speed and direction and internal to external temperature difference. Uses statistical method to compare results from the two residences and concludes that temperature coefficients were statistically different but that wind coefficients were not. Finds high dependence of infiltration rates on indoor to outdoor temperature difference and that values for air leakage obtained from current methods of estimation were lower than those actually experienced.