tracer gas

Describes how ventilation rates in two houses with recirculating air distribution systems were monitored by injecting CO2 tracer gas into the supply and measuring its concentration in the return air. In one house with solid concrete floor, normal windows and air bricks, ventilation rates were mainly dependent on wind speed. In the other with suspended timber floor and weatherstripped windows ventilation rates were much lower and mainly dependent on internal to external temperature difference.

Gives general account of Twin Rivers project summarising main findings from 1972 to date. Includes section on air infiltration. Measurements of infiltration rates were taken using tracer gas method and regression equation found for the data.

The measurement systems used at Twin Rivers for determining energy usage are described. These include a weather station, three different systems for the measurement of temperatures and energy-related events in a house, a tracer-gas based air infiltration measurement system and infrared thermography

Developes mathematical model of air infiltration based on crack flow equations. Describes measurements made on test house. Shows that actual pressure distributions in walls deviate considerably from values in guidebooks. Finds background leakage area of house by pressurizing house with electric fan and measuring pressures. Suggests two distributions for leakage areas. Measures infiltration rate using helium tracer gas, recording temperature and pressure differences. Concludes that comparison between prediction and experimental results is encouraging.

Describes the determination of infiltration rates for houses in Seneffe. Gives infiltration rates for individual rooms, found using O2 as tracer gas, and recording wind speed and direction. Determines global air renewal rate using N2O as tracer gas, by injecting gas through ventilators into all rooms and measuring concentration in each room. Calculates global concentration from individual measurements.

Measurements of the dynamic heat transfer in a four-bedroom townhouse were made under controlled conditions in a large environmental chamber to explore the viability of a computer program developed at N.B.S. labelled NBSLD for predicting heating and cooling loads and inside temperatures. Test house was factory-produced, of modular design and lightweight (wood) construction. Tests were performed with simulated outside summer, winter and autumn diurnal temperature cycles. Inside temperature was maintained at 75 f and the activities of a six-member family were simulated.

Presents description of an automated, controlled-flow air infiltration measurement system. This system measures total air flow, a volume per unit time, due to infiltration in a test space. Data analysis is discussed and the mixing problem analysed. Different modes of operating the system are considered : (1) concentration decay, (2) continuous flow in a single chamber and (3) continuous flow in a multichamber enclosure. Problems associated with the use of nitrous oxide as a tracer gas are described.

Practical measurement has shown that gasoil and candle flames provide constant tracer gas sources. Suggests their use for meaSuring ventilation. suggests application in temporary dwellings such as caravans, using candle as simulated "people" consuming oxygen and producing heat and carbon dioxide. Describes measurement methods using natural decay exponential equation. Graph illustrates sequence when air change rate fulfills requirements in swedish building code 1975 of 0.5 change/hour.

Outlines parameters governing air infiltration. Discusses problem areas of house to house comparisons of air leakage. Deals primarily with tracer gas procedure as compared with pressurisation/depressurisation approach. Describes testing in townhouses of recent construction as well as in a number of older homes of varied design. Uses roof-top laboratory test chamber to examine relations between wind effects, buoyancy effects and building openings and how they effect air infiltration. Uses results to clarify evaluation of air infiltration.

Describes how in 1960-62 National Research Council of Canada conducted air infiltration measurements on 2 single-storey houses using helium as a tracer gas, followed in 1967-68 by measurement of air leakage characteristics using house pressurisation technique. Describes procedure developed from these tests for calculating infiltration rates. Gives equations for calculating infiltration due to stack effect and that due to wind action. Gives equation for combined effect.