helium

Based on the age concept, the performance of the following three principle ventilation schemes have been monitored (supply air terminal - extract air terminal), ceiling-ceiling, ceiling-floor, floor-ceiling. All systems used only air for both heating and cooling. Contaminants with both greater, less and approximately the same density as air were released at a point source. The tests were both carried out in an empty room and with a person (heated mannekin) in the room.

Presents results of measurements of ventilation rates in the SEGAS test house. Describes the house and its heating and mechanical ventilation systems. Measurements of ventilation rates were made using helium as a tracer gas. Tests were made both with the house sealed to block obvious paths of infiltration and with it unsealed. Tests were also made with the house mechanically ventilated and with supply and extract systems working. Presents results of tests and examines the effect of variation in mean wind speed on ventilation rates.

Describes an instrument for the measurement of air infiltration into buildings. The instrument indicates the concentration of a tracer gas in the building, by sensing the thermal conductivity of the air-tracer gas mixture.< The instrument, a Katharometer, has not been extensively used because of inherent difficulties. This thesis examines the dificulties. An analysis of the theoretical basis of the instrument is made and the problems created by changes of relative humidity, pressure and temperature are discussed and solutions are suggested.

Gives formula for calculating air-change-rate from decay rate of a tracer gas. Discusses different tracer gases and detecting instruments. Describes portable meter used to measure the concentration of helium. Discusses its performance and describes the experimental procedure.

Reports investigation of air infiltration in two residences using helium as a tracer gas. Describes the residences, instrumentation and test procedure. Gives results of decay rate of tracer gas and measured infiltration rates. Summarizes test conditions in tables of temperature, wind speed and direction, internal to external pressure differences and height of the neutral zone. Concludes that in houses with warm-air heating systems a single helium analyzing cell in the return air-stream would provide a satisfactory indication of house infiltration rate.

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.