AIVC - Air Infiltration and Ventilation Centre

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natural ventilation

Automatic measurements of air change rates (decay method) in a small residential building without any forced air-heating system.

Describes an automatic measurement system for air infiltration and discusses factors influencing the measurements in single rooms or in a group of connected rooms. The system works on the decay rate method and is controlled by a purpose-designed controller. The test data are evaluated off-line by computer. Discusses in detail the instrumentation and test procedure Gives results of measurements made in a detached house and correlations of the test data with wind and temperature difference data. Gives a comparison with pressurization data.

The natural ventilation of tall office buildings.

Reports study of the natural ventilation in elementary tall office buildings has been made using the analogy between the flow of air through a building and the passage of an electric current through a circuit of resistances. The prime motive forces, those of wind pressure and stack effect are detailed, and experimental values for these and other parameters related to the building are outlined.

Ventilation rates

Treats investigations in office building where 1) flow rates of supply air, return air and ventilation between main office area and adjacent rooms were measured with an anemometer. Return air rates remained constant but ventilation rates varied widely during measurement periods. 2) CO2 was used as tracer gas to determine ventilation rates in offices. Calculates alterations in gas concentrations in rooms adjacent to stairwell and changes in outdoor air concentrations. During air conditioning, ventilation rates in the room were 4-5 room air changer per hour.

Fuel consumption in industrial buildings

Compares annual fuel consumptions of seven large factories against calculated requirements to illustrate seasonal thermal efficiencies of 7.7 to 49.7%. Shows that ineffective and uncontrolled ventilation is by far the most significant factor in excess fuel consumption. Illustrates savings of 38 to 80% in fuel which have been achieved. Shows that fuel savings of 20 to80% are possible in the factories studied, with 35 to 95% savings possible when heat recovery is provided in addition to other improvements.

The feasability of using models for predetermining natural ventilation.

Discusses conditions that must be satisfied for a model in a wind-tunnel to give the same air-flow as a full-sized building. Reports two series of tests on interior and exterior air flow patterns, made on a full-sized building and a scale model of the building. Air flow patterns were observed using titanium tetrachloride smoke. Tests were also made to determine the limits by which the product of the height of the model by the air speed may vary without serious error.

Natural ventilation of large hospital buildings.

Wind-tunnel tests of hospital scale models and a computer program to calculate internal air flows were used to produce aprediction technique to determine the rates of natural ventilation of large hospitals. Technique was applied to aharness hospital design and article reports that the ventilation generated by wind forces in for instance, ward areas would not be consistently adequate for the comfort and well-being of the occupants.

Natural ventilation and energy consumption

Gives preliminary report of a study of natural ventilation and energy consumption in low-cost housing. The study includes the measurement of infiltration rates using tracer gas, pressure differences across outside walls, indoor and outdoor temperatures, air tightness of external walls and the position of windows and doors. Outlines future studies and gives preliminary conclusion that making houses more air tight can save energy.

Measurement and calculation of the ventilation through a vertical sash-window without wind. Messungen und Berechnungen uber Stossluftung durch vertikal Schiebefenster bei Windstille.

Reports measurements of the natural ventilation through a vertical sash-window in calm weather. Describes test window and room. Gives theoretical expression for the ventilation depending on the amount the window is open, inside to outside temperature difference and the difference in height of the openings. Reports two tests of ventilation rate made using smoke. Concludes that a vertical sash window gives very good ventilation even without wind. Finds that tests corraborated the formula which would also apply to a deeper room.

An investigation of air exchange between rooms and outside air. Untersuchung uber den Luftaustausch zwischen Wohnraumen und Aussenluft.

Natural ventilation of inhabited rooms is studied with regard to its dependence on wind velocity and temperature difference between the interior of buildings and outside air. On the basis of simultaneous aerosol and carbon dioxide measurements an attempt has been made to separate the two components of air exchange: ventilation through walls and ventilation through clefts and chinks.

The natural ventilation of unheated closed rooms.

Reports investigation of the relative effectiveness of wall gratings and flues as means of naturally ventilating unheated closed rooms. Ventilation rates of several rooms were measured using carbon dioxide as tracer gas and wind speed and direction were recorded. Presents results and finds for the flue, ventilation increased with wind speed irrespective of direction. For grating, ventilation rate increases slowly with size of grating and is dependent on both wind speed and direction. Concludes flue with base opening of 15 sq.ins. is as efficacious as grating having 50 sq.ins.

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