Briefly overviews some of the available instrumentation and techniques that could be used by the home-owner, or professional auditor to evaluate energy use in houses. Includes descriptions of the "blower door" method for evaluating air leakage, and some tracer gas techniques for measuring air infiltration.
Describes a simple, inexpensive sampling technique for infiltration measurement using SF6 tracer gas. Uses pre-evacuated blood collecting test tubes with rubber stoppers for sampling. This is controlled by a micro-processor driven automatic sampler, which drives a hypodermic needle through the rubber stopper to fill the tube with an air sample. Analyzes samples using a gas chromatograph. Releases SF6 at ground level in a high-rise cold store and collects samples of air at different heights to see if stratification is present.
Measures air exchange across open cold store doors using an anemometer and by tracer decay methods. Anemometer results show that an empirical factor of 0.68 should be applied to the predictive equation by Tamm. Observes a further reduction in air change rate (about 47% reduction) due to imperfect mixing of the air. Air curtains reduce infiltration by about 75-80% and plastic curtains by approx. 93%. Forklift traffic and internal circulation fans also affect air change rate.
Uses a two-region model to predict infiltration, to take into account non-ideal mixing of tracer gas in a building. Considers versions of this model:< 1. Fluid flows between the 2 regions and the environment in any manner provided steady state and mass balance are maintained.< 2. There is limited interchange between the regions< 3 Air flows into the first region and out of the second with (unbalanced) interchange between the two.< 4. The second region is a "dead-water" zone, which is not directly connected with the outside.<5.
Describes air leakage and tracer gas (SF6) measurements made in 42 Scottish houses. Finds that leakage in the "test" (better insulated) houses are on average 10% higher than that in the "control" houses. About 40% of the total leakage rate (at a pressure difference of 50 Pa) flows into houses through thefloor boards and the air-bricks under the crawl spaces. Tracer gas measurements indicate that average leakage rates with closed windows lie between 0.52-1.65 air changes per hour. Opening a window can increase the number of air changes by a factor of 2 to 5.
Reports on an extension of the metabolic CO2 method for ventilation measurement to a naturally ventilated room having air flow connections with other internal spaces as well as the outside. Uses an infra-red gas analyser to monitor CO2 concentrations in the fresh air outside and also within theroom, the corridor and the ceiling space. An automatic unit switches the analyser between 6 sampling points. Comparison of the data with results from SF6 tracer gas decay methods gives close agreement.
Describes a technique for measuring air flows between internal zones of houses. Gives the theory of measuring one and two directional flows and describes the equipment used for practical measurements. Uses Freon 12, Freon 114 and BCF as tracer gases, and measures their concentrations using a gas chromatograph. Includes specimen results of one and two directional flows between a house and its roof. Discusses the possible applications of the method in houses.
Using miniature perfluorocarbon tracer (PFT) sources and miniature passive samplers, tests conducted in the lab and in a typical home successfully demonstrate the utility of the PFT kit as a means for implementing wide-scale infiltration meas
Examines airflow in the Glowworm cave of New Zealand using conventional methods together with experimental procedures using SF6 and CCL2F2 tracer gases. Results show that the rate and direction of airflow are a direct response to a thermally
Uses the SEGAS "Autovent" constant concentration apparatus to measure the fresh air entering and the local ventilation rate in each cell of amulti-celled dwelling with both natural and mechanical extract ventilation. Measures fresh air entry into each cell using tracer gas constant concentration and decay techniques. Conducts decay tests without artificial mixing, and interprets them by computing the area under the decay curve to obtain local ventilation rates. Compares the 2 measurements, giving the ventilation efficiency of each cell and an idea of air quality in each room of the house.
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