Describes a series of experiments to determine the ventilation performance of 2 different models of wall or window mounted heat exchangers. Determines their nominal efficiency by the measurement of tracer gas decay rates at several indoor locations. Notes significantly higher local ventilation efficiencies in rooms where heat exchangers are operating. Some preliminary tests indicate that internal leakage between the air streams contribute significantly to the ventilation inefficiency of these systems.
Air change rate is often reported as a single number, with no attention paid to different values of air change rate in different zones of a building. This may affect air quality evaluation as there may be undetected zones where air change rate is too small, resulting in localized pollutant concentrations. Describes a multi-point tracer gas technique used to quantify air change ratein different zones of various residential buildings. Defines and calculates zonal ventilation efficiency terms, and proposes a criterion for analysis of the results for indoor air quality evaluation.
Uses a two-zone model to describe the concept of and to define the effectiveness of ventilation. Deals with multiroom aspects and procedures for measuring ventilation effectiveness. The simple two-zone model predicts generally high effectiveness for ventilating systems using the displacement principle, taking advantage of stratification. Reviews tests using thisprinciple in an office room for 1-3 people (28 sq.m., 2.8m ceiling height).
The concept of age, or residence time is applicable to characterize both how the supplied air or a contaminant is spread within an enclosed space and how quickly a contaminant is removed. Discusses the application of the concept toany enclosed space with air intakes and extracts. Establishes a direct relationship between the age concept, exposure to contaminants, and equilibrium concentrations. Treats different tracer gas techniques for measuring the age distributions and derived quantities.
Correlates hourly infiltration in 3 adjacent unoccupied test houses to determine the relative contribution of wind and stack effects. The database, obtained using tracer gas techniques over 2000 hourly readings in each house, is sorted to a single 45 degree sector. Different weather sealing techniques give mean infiltration rates of 0.19, 0.45, and 0.59 ach for the 3 houses. Addition of independent wind and temperature induced pressures correlate only part of the weather induced data variability leaving a residual RMS scatter of about 0.004 ach.
Investigates the reliability of the single-room infiltration model used in the computer program ENCORE. Compares calculated air change rates with tracer gas (N2O) measurements in 25 identical one and a half storey detached houses. Describes the infiltration model, the parameters and some results. Thecomparison shows good correlation at low wind speeds (< 3m/sec) but the model's values at higher wind speeds are too high.
Studies the predictive accuracies of infiltration-pressurization correlation models by subjecting a group of identical homes in Freehold NJ to both pressurization and tracer gas measurements of infiltration. Compares infiltration and pressurization test results. Uses four air infiltration models to predict the infiltration rates in the houses, and compares these predictions with the measured rates. Makes predictions using several different values of the inputs required for the models, and studies the effects of varying these inputs.
Presents the underlying theoretical basis for measuring air flows in complex, multi-cellular buildings and by reviewing the existing experimental procedures which enables the carrying out of these measurements. Shows that inter-cell air flows can be determined only by generating N sets of tracer gas conservation equations, where N is the number of cells. Describes 3 systems being designed to carry out multi-cell ventilation measurements< 1. "grab sampling"< 2. multiple tracer measurements< 3. measuring averaged air change rates over long periods.
Examines a new energy conservation technique based on the control of the "fresh air intake" through measurement of CO2 content in extracted air for different kinds of buildings. Assesses various techniques for measuring CO2 concentration in view to design a low cost sensor, concludes that theinfra-red absorption technique is the most suitable. Shows through computer simulation that a CO2 based ventilation system can provide a better pay-back period than an air-to-air heat exchanger.
Describes a project aimed at developing a method of measuring air infiltration rates in large single cell enclosures and buildings, and of using the method to collect data on actual infiltration rates. Makes a brief survey of existing and novel methods of measuring air infiltration rates. Identifies 2 methods which merit further consideration - the use of methane as a tracer gas,measuring its concentration with an infrared laser technique; and the use of ethanol vapour as a tracer gas, measuring its concentration with a fuel cell detector.
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